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• Al/BaTi 1-2x Fe x Nb x O 3 /Ag is an excellent bulk ferroelectric photovoltaic device configuration. • Increment of aliovalent Fe3+ and Nb5+ ionic substitutions reduces the bandgap of 0.075BFNT ceramics to ∼2.55 eV and broadens the visible spectrum absorption. • The photocurrent density of Al/0.075BFNT/Ag photovoltaic cell is about ∼ 2.2 times higher than that of pure BT. • A high photovoltaic power of ∼ 12 μW/cm2 was achieved. The generation of above bandgap photovoltage using bulk ferroelectric materials has become a subject of great interest, however, their photocurrent density is limited by a broad bandgap and poor conductivity. To overcome this limitation, we replaced aliovalent metal ions (Fe3+ and Nb5+) at the B-site of robust ferroelectric BaTiO 3 and fabricated an Al/BaTi 1-2x Fe x Nb x O 3 /Ag photovoltaic device. Both the experimental and the theoretical studies showed that bandgap was lowered to ∼2.55 eV and hence absorption of wide energy range of the solar spectrum was attained. An apt top electrode, reduced bandgap and domain size resulted in greater photocurrent density of 1.46 μA/cm2 and photovoltage of 8.31 V for Al/0.075BFNT/Ag solar cell in unpoled condition. This research suggest that reduced band gap, mixed structural phases and nano-sized domains suffices greatest PV power output while the large polarization and poling are not necessary prerequisites. [ABSTRACT FROM AUTHOR]

This study reported the activity of catalysts synthesized from platinum and molybdenum alloys in different atomic ratios and used as cathode electrocatalysts in the PEMFC. The structural properties of PtMo/C and Pt/C catalysts were analyzed by XRD analysis. The composition and distribution of these alloys in Vulcan XC-72R Carbon were determined by SEM and EDX techniques. CV studies assessed electrochemical properties such as ORR and ECSA activity. The performance of PEMFC cathodes that supplied pure hydrogen and oxygen was examined using polarization curves at different temperatures. Another way to improve the cathodic reaction is to use ozone as a potent oxidizing agent. It was measured that the OCV of the H 2 /O 3 PEM fuel cell was 1.60 V, much greater than the open circuit voltage of the traditional H 2 /O 2 PEM fuel cell. The PtMo/C catalyst achieved its highest power density of 137 mWcm−2 at 70 °C, 128 mWcm−2 at 60 °C, 101 mWcm−2 at 50 °C, and 85 mWcm−2 at 40 °C when exposed to H 2 /O 2. As the temperature of the cell was raised, it was seen that the catalyst's catalytic activity increased. The maximum power density was detected to be inversely related to the rise in temperature when ozone was used. At low current densities, however, ozone was observed to greatly boost activation polarization. [Display omitted] • The use of PtMo/C catalyst as a cathode affects the power density of the cell. • PtMo/C produces the highest power density in a PEM fuel cell when using H 2 /O 2. • Using H 2 /O 3 , the PtMo/C catalyst gave the best results in the low-current density region. • The PtMo/C catalyst has the best activity at increasing cell temperature when using H 2 O 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Application of [Fe 4 S 4 ] to metal-ion batteries is studied using DFT calculations. • Embedding [Fe 4 S 4 ]2+ clusters in metal–organic frameworks generates high voltage. • The electrochemical performance is based on an intercalation mechanism. • Among the screened material pairs, Zn2+-BMOF shows the highest efficiency. [Fe 4 S 4 ] clusters have served as molecular batteries and charge transfer centers in many biosystems. However, their potential as electrode materials has been overlooked amidst the ever-increasing studies on various materials in the search for efficient battery compositions. To evaluate their electrochemical efficiency as electrode materials, we focused on the use of two important oxidation states, [Fe 4 S 4 ]2+ and [Fe 4 S 4 ]⁰, in a series of Li-, Na-, K-, Mg-, Ca-, and Zn-ion batteries. We also assessed the effect of metal–organic framework (MOF) formation on their performance by studying [Fe 4 S 4 ]2+-1,4-benzenedithiolate MOF (BMOF) and its carboxylate-based counterpart (CMOF). Our model-based Density Functional Theory (DFT) calculations indicated that oxidation of the cluster to [Fe 4 S 4 ]2+ and MOF formation significantly improve the electrochemical efficiency of the cluster. Among the studied electrode materials and metals, the BMOF combination with Mg0 and Zn2+ presented the best electrochemical performance. Notably, our periodic calculations indicated an open circuit voltage of 4.32 V for the Zn2+-BMOF system, suggesting a promising performance for BMOF compared to other cathode/negative electrode materials. Our atomic and electronic structure analyses indicated that intercalation is the underlying electrochemical mechanism. [ABSTRACT FROM AUTHOR]

In the search for next-generation energy storage devices, superior-performance alternative electrode materials based on two-dimensional materials for rechargeable metal-ion batteries are essential. Here, we explored group III and IV functionalization of 2D Ti 2 B, Ti 2 BX 2 (X=Si, Ge, P, As) as anode materials for Li and Na ion batteries using first-principles calculations. The structures had excellent metallic properties and demonstrated energetically favorable adsorptions for metal ions. Analyzing charge transfer and electronic band structures, silicon and phosphorous-functionalized Ti 2 B (Ti 2 BSi 2 and Ti 2 BP 2) showed the most potential. The energy band diagrams showed that both Ti 2 BSi 2 and Ti 2 BP 2 had metallic characteristics after Li and Na-ion adsorption, which offered considerable advantage for rechargeable-ion batteries. The structures exhibited low energy barriers for Li and Na-ion migration. The minimum energy barriers calculated for Na were 0.08 eV for Ti 2 BSi 2 and 0.24 eV for Ti 2 BP 2. Theoretical specific capacity and open circuit voltage were calculated using maximum layer adsorption. For both Li and Na, high values of specific capacity and low values of open circuit voltage (¡ 1 V) were found. Ti 2 BSi 2 had the best performance, with a theoretical specific capacity of 1647.10 and 1317.68 mA h/g for Li and Na, respectively. Its open circuit voltages for Li and Na were 0.65 and 0.38 V. The insights of this study will be beneficial in fabricating high-performing Ti 2 BX 2 -based anodes for rechargeable Li and Na ion batteries. [Display omitted] • Functionalized 2D MBene Ti 2 B were explored for potential applications as anode materials in rechargeable ion batteries. • Functionalized Ti 2 B structures were both dynamically and energetically stable, with excellent metallic characteristics. • High theoretical specific capacity, low open circuit voltage, and low diffusion barriers were revealed for the proposed functionalized structures. • Comparative analysis with literature verifies that the proposed structures demonstrated significant promise as anode materials. [ABSTRACT FROM AUTHOR]

The paper presents an overview of studies of the multi-junction (MJ) solar cells (SC) with IV characteristics having nonlinear peculiarities. It is shown that such peculiarities can arise either due to hetero-interface barriers (HB) for majority charge carriers or due to problems with tunnel diodes (TD). It is usually difficult to identify which of these hetero-structural objects is the cause of this nonlinearity, since the peculiarities appear similarly in the IV characteristics of MJ SC. The experimental method presented in this work is based on the study of IV characteristics during the overheating of MJ SCs. The behavior of nonlinear peculiarities caused by an imperfect TD or an HB is fundamentally different during the overheating of SCs, which makes it possible to identify the type of hetero-structural object. Since the number of hetero-interfaces in MJ SC is large, a method determining the position of problematic objects in the MJ structure was also developed. The method is based on the illumination of individual subcells using different laser wavelengths. Both methods considered were tested experimentally on GaInP/GaAs/Ge SCs. • Heterobarriers and tunnel diodes can be responsible for nonlinear peculiarities arising in the IV characteristics of MJ SC. • The search for non-optimized layers position inside the SC structure can be performed using specialized structures. • Non-optimized tunnel diode could lead to the presence of an open-circuit voltage drop. • Temperature reaction of IV characteristics allows determining the type of object that gives a nonlinear peculiarity. • Analysis of such a reaction allows us to determine the position of non-optimized hetero-barriers. [ABSTRACT FROM AUTHOR]

LiFePO4 batteries are increasingly utilized in electric vehicles due to their superior safety. Accurate state estimation is the basis for the safe and reliable application of LiFePO4 batteries. However, the flat voltage characteristics of LiFePO4 batteries lead to state estimation closed-loop correction as its inherent contradiction. To address this challenge, a model-based SOC estimation method combining proportional-integral-differential (PID) observer and improved extended Kalman filter (EKF) is developed according to different open-circuit-voltage (OCV) ranges, specific processes include: First, an exponentially weighted moving average algorithm with a temperature compensation factor is presented to compensate for the errors in the identified OCV. Secondly, the combination of the PID observer and EKF is chosen adaptively to update SOC within distinct OCV ranges, differentiated by the identified OCV. To achieve optimization of the PID parameters and temperature compensation factors across varying temperatures, an enhanced whale optimization algorithm is developed. To validate the developed method, a series of experiments are performed across a range of temperatures and with multiple driving profiles. The results show that the developed method not only guarantees maximum absolute error of <3 %, but also can converge quickly in the early stage. • A temperature compensation factor (T c) is used to reduce the error of identified OCV based on EWMA-FFRLS. • A PIDO combined with an improved AEKF is presented to accelerate the SOC convergence speed. • An AEKF-PIDO-integrated US-EKF framework is developed to enhance SOC estimation of LiFePO4 battery. • An improved WOA is introduced to adjust the PIDO parameters and T c at different temperatures. [ABSTRACT FROM AUTHOR]

In this theoretical research, four distinct acceptor molecules (M-M3) having structural configuration A 2 -D-π-A 1 -π-D-A 2 have been designed through terminal acceptor and linker alteration. The DFT-based approach B3LYP/6–31 G (d, p) has been used to study the photovoltaic properties of designed molecules. A number of characteristics of these molecules have been assessed comprehensively. The designed molecules M-M3 have exhibited lower energy gap (1.56–1.63 eV) as compared to the reference molecule (E g = 1.70eV). A red shift in absorption was observed for all the molecules (λ max = 964 –1005 nm) as compared to the reference molecule (λ max = 693 nm). Nearly identical outcomes from density of states and frontier molecular orbitals for all the altered molecules show that electron density is evenly dispersed across the entire molecules. Additionally, their slightly greater dipole moment and smaller excitation energy as compared to reference molecule are responsible for their remarkable charge transfer because of better separation of electron-hole pair (exciton). Calculating open circuit voltage of the examined acceptor molecules with respect to P113 donor have revealed that all the newly proposed molecules M-M3 exhibit higher V OC (1.25–1.36 eV) and FF. The results of this study imply that the fabrication of solar cells using these designed acceptor molecules may result in high photovoltaic yield. [Display omitted] • Four novel diketopyrrolopyrrole based acceptor molecules (M-M3) were proposed. • All the molecules were analyzed computationally by Gaussian 09 using DFT. • Designed molecules exhibited lower band gap and a bathochromic shift in λ max. • Designed molecules show raised open circuit voltage and FF. [ABSTRACT FROM AUTHOR]

[Display omitted] • 1,3,4-oxadiazole derivatives were designed for efficient NLO response. • A larger NLO for 6-oxza is attributed to its lowest transition energy of 3.78 eV. • Unlike PCM solvation method, the gas and COSMO salvation methods show good agreements. • Frequency-dependent γ values revealed that derivatives are suitable for wide range of frequency and laser application. • For photovoltaic applications, the V oc and ΔG reg for 6-oxza are found to be 2.22 and 1.87 eV. The science of organic optical and nonlinear optical (NLO) materials has been captivating the scientific community owing to their extensive applications in optoelectronics, OLEDs, and telecommunications. This study presents the design and investigation of novel organic compounds of pyrene and 1,3,4-oxadiazole derivatives (1-oxza to 6-oxza), featuring various push–pull combinations. Quantum chemical calculations were employed to determine linear polarizabilities (α) and third-order NLO polarizabilities (γ). Notably, the largest average third-order NLO polarizability value was found to be 254.9 × 10−36 esu for the finely tuned push–pull system 6-oxza , which is ∼35 times greater than that of the prototype NLO molecule of p -nitroaniline (p -NA). Among the derivatives, 1-oxza exhibits the highest linear isotropic polarizability (α iso) value of 61.59 × 10−24 esu, while 5 -oxza displays the highest linear anisotropic polarizability (α aniso) value of 60.09 × 10−24 esu. A notable increase of approximately ∼1 to ∼2 times in < γ > is observed for selected compounds (1-oxza , 4-oxza , 6-oxza), indicating that the Conductor-like Screening Model (COSMO) overestimates the values compared to the polarizable continuum model (PCM) and gas phases. Solvent significantly enhances third-order NLO polarizability amplitudes depending upon solvent polarity and strength of substitution groups. We calculated the frequency-dependent third-order NLO polarizability of 6-oxza at laser wavelengths ranging from 1400 to 1970 nm. The second hyperpolarizability EFISHG process (γ(−2ω; ω, ω, 0)) was calculated at a laser wavelength of 1400 nm, and the γ-amplitude was found to be 400.1 × 10−36 esu. The remarkable hyperpolarizability response in the gas phase is corroborated by TD-DFT calculations, which reveal a larger transition dipole moment of 3.062 and a lower transition energy of 3.780 eV as origin of larger hyperpolarizability for 6-oxza. A comprehensive analysis was performed based on FMOs for designed compounds to elucidate the intramolecular charge transfer (ICT) mechanisms and observed a notable reduction in energy band gap 4.89 eV for 6-oxza, which is responsible for enhanced NLO response. Additionally, DOS maps revealed the quantitative contributions of HOMOs and LUMOs for crucial electronic states related to the efficient ICT process. Additionally, we analyzed the photovoltaic properties and found that 6-oxza has the highest dye regeneration and the lowest open-circuit voltages of 1.89 eV and 2.22 eV, respectively. Our designed model compounds can put real-time such compounds under spotlight of scientific interests which seeks more efficient optical and NLO properties. [ABSTRACT FROM AUTHOR]

Within this piece of research, the performances of pure B 2 CN 3 nanosheet (PB 2 CN 3 NS) and its doped structure with Si atoms (SB 2 CN 3 NS) as the anode materials of K-ion batteries (KIBs) were investigated using DFT. The findings showed that PB 2 CN 3 NS and SB 2 CN 3 NS are highly capable of adsorbing K with acceptable adhesion energy (AE). Also, because of the negative adhesion of K+, in comparison with K, K+ donated more electrons on PB 2 CN 3 NS and SB 2 CN 3 NS. Based on the results, SB 2 CN 3 NS provided an ideal condition for the K atoms to migrate on the surfaces of PB 2 CN 3 NS and SB 2 CN 3 NS because of their lower energy barrier. The computed theoretical storage capacity was approximately 1347 mAh.g−1 after the adhesion maximum K atoms onto PB 2 CN 3 NS and SB 2 CN 3 NS. This value is higher the values reported for many anodes materials fabricant in recent years. The open circuit voltage (V OC) of PB 2 CN 3 NS and SB 2 CN 3 NS were also found to be low, which were 0.19 and 0.25 V, respectively. The outcomes within this study can provide useful insights into producing highly efficient anodes for KIBs. [ABSTRACT FROM AUTHOR]

Currently, A−π−A configured molecules (TTP1-TTP6) were designed from the reference compound (TPPR) by modifying the terminal acceptors for photovoltaic materials. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) using the M06/6-311G(d,p) functional were employed to analyze the photonic and electronic properties of the newly designed derivatives. Various analyses; frontier molecular orbitals (FMOs), density of states (DOS), absorption spectra (λ max), transition density matrix (TDM), binding energy (E b), hole-electron and open circuit voltage (V oc) were performed to explore the photovoltaic properties of triphenylpyridine based compounds. The structural modulation with acceptor moieties significantly tuned their HOMO and LUMO levels, resulting in reduced band gaps (2.833–3.037 eV). They also exhibited broader absorption spectra (λ max) ranging from 482.560 to 514.756 nm as compared to the reference compound (486.289 nm). Notably, TPP3 showed the good photovoltaic response as it displayed the least energy gap (2.833 eV) with lower binding energy (0.415 eV) and bathochromic shift (512.798 nm) in absorption spectra as compared to all other derivatives. Beside this, a comparative study with spiro-OMeTAD and P3HT standard hole transport materials illustrated that these materials can also be utilized as effective photovoltaic materials. [ABSTRACT FROM AUTHOR]

It has been reported that a solar cell containing a 1.077 eV bandgap absorber can achieve actual open circuit voltage up to 0.93 V and power conversion efficiency up to 35% at 300 K when the cell is irradiated by the air mass 1.5 global solar spectrum [M. S. Reza et al. Opt. Commun. 561 (2024) 130511]. These simulated open circuit voltage and power conversion efficiency values exceed the ideal detailed balance-limiting values. Even in the "limiting case" of small defect concentration and large acceptor doping concentration, the modeled open circuit voltage and power conversion efficiency are unphysical because they exceed the well-known detailed balance limit. Therefore, the results presented by Reza et al. are incorrect. • Ideal performance of a 1.077 eV solar cell determined from detailed balance. • Maximum open circuit voltage is 0.8373 V (AM1.5G, 300 K). • Maximum power conversion efficiency is 32.19% (AM1.5G, 300 K). [ABSTRACT FROM AUTHOR]

The development of high-efficiency and stabilized tandem solar cells and solar cells for indoor light harvesting relies heavily on the fabrication of wide-bandgap (WBG) perovskite solar cells (PSCs) that exhibit exceptional efficiency and stability. In this study, we introduce an effective method for enhancing the optoelectronic properties of a 1.74 eV WBG perovskite absorber by interfacial engineering. Specifically, we utilize 4F-Phenethylammonium Chloride (4F-PEACL) as a key component for the surface treatment of perovskite layer. The treatment of perovskite with 4F-PEACL alters the surface stoichiometry, promoting self-doping and surface passivation, reducing surface recombination, and improving the optoelectronic properties of perovskite. Consequently, PCSs with perovskite treated with 4F-PEACL exhibit a notable power conversion efficiency of 20.27 %. Furthermore, the devices subjected to 4F-PEACL treatment demonstrate enhanced stability compared to the control devices across a range of testing settings. The findings of our study indicate that the utilization of organic salt perovskite passivation holds great potential in the development of efficient and stable WBG PSCs. [Display omitted] • Perovskite surface treatment with 4F-Phenethylammonium Chloride (4F-PEACL). • 4F-PEACL affects the perovskite surface stoichiometry. • The proposed treatment induces self-doping and surface passivation of perovskite. • The optimized devices exhibit a PCE of 20.27 %. [ABSTRACT FROM AUTHOR]

Designing efficient, non-fused ring-based organic solar cells (OSCs) with high open circuit voltage is a significant challenge. The present research proposes seven novel moieties generated from an existing 4T2CSi–4F (R) asymmetric molecule to increase efficiency. The density functional theory (DFT) was used to examine several essential characteristics like optical, electronic, and efficiency-related properties of molecules. It is revealed that newly presented molecules have superior features that are required to manufacture efficient organic solar cells. They exhibit a lower band gap between 2.05 and 2.34 eV and have a planar shape. Six moieties exhibit lower excitation energy values in the gas and chloroform phases, and five moieties have more excellent dipole moments than the R molecule. UA1 and UA2 show remarkable enhancement in the optoelectronic properties, exhibiting the greater λ max at 773 nm and a smaller excitation energy of 1.60 eV. All the newly presented molecules have lower ionization potential and reorganization energies of the electron. The open circuit voltage (V oc) of five newly designed molecules is greater, varying from 1.40 to 1.55 eV, than R (V oc = 1.38 eV). Furthermore, the newly designed molecules, except UA1 and UA2, show more excellent fill factor (FF) than the R molecule. This significant increase in efficiency-associated metrics (FF and V oc) suggests that these molecules may be effectively implemented to manufacture an upgraded version of OSCs. • Seven new molecules were designed for improving the optoelectronic properties. • All the molecules were processed computationally by using DFT approach. • Newly designed molecules have small bandgap, less excitation energies. • Designed molecules show improved light harvesting efficiency, electron mobility and electronic cloud dispersion, open circuit voltage and FF which makes them superior choice as compared to reference molecule. [ABSTRACT FROM AUTHOR]

In current study, six novel selenopheno-thiophene (ST) core-based chromophores (SePTD1- SePTD6) with A-D-A configuration were designed via structural tailoring with terminal acceptors of SePTR. The optoelectronic and photovoltaic properties of SePTD1-SePTD6 were explored through TDDFT/DFT approaches. The B3LYP/6–31 G(d,p) level was chose through benchmarked study with the help of DFT and experimental UV-Vis values of SePTR. All tailored chromophores exhibited a comparatively smaller band gap (2.144–2.003 eV), along with a significant bathochromic shift (676.8–724.2 nm) and an increased rate of charge transference then reference chromophore (2.119 eV and 686.6 nm). Among all derivatives, SePTD2 exhibited some unique characteristics such as, least HOMO/LUMO energy gap (2.003 eV), highest absorption values (665.4 nm in gas and 724.2 nm in solvent), least binding energy (0.291 eV) and also significant value of open circuit voltage (1.860 V). The aforementioned findings suggest that employing molecular engineering with extended acceptors enhances the photovoltaic performance of non-fullerene materials, thereby encouraging experimentalists to develop highly efficient photovoltaic devices. • Designing of selenopheno thiophene core-based chromophores for OSCs. • Structural modeling with π -spacer and acceptor moieties. • Exploration of photovoltaic behavior of designed chromophores. • Study of key electronic properties at B3LYP/6–31 G(d,p) functional. • Utilization of TD-DFT approach for FMOs and UV-Vis analyses. [ABSTRACT FROM AUTHOR]

The electrical and thermal performance of an unglazed photovoltaic thermal (PVT) system integrated with a serpentine coil configured sheet and tube thermal absorber setup was evaluated using water and copper oxide-based nanofluid. An uncooled PVT system reached a maximum panel temperature of 68.4 °C at noon and obtained an average electrical efficiency of 12.98%. Water and nanofluid cooling of the PVT system reduced the panel temperature by 15 °C and 23.7 °C at noontime, respectively. Compared to the uncooled PVT system, the average electrical efficiency of water and nanofluid cooled PVT system increased by 12.32% and 35.67% to obtain 14.58% and 17.61%, respectively. The thermal efficiency of the nanofluid cooled PVT system (71.17%) was significantly higher than water cooling (58.77%) due to maximum heat absorption by nanoparticles. It was also observed that the overall efficiency of the nanofluid cooled PVT system was 21% higher than the water-cooled system. Also, obtained the highest primary energy-saving efficiency for the nanofluid cooled PVT system. [ABSTRACT FROM AUTHOR]

The rapid expansion of the electronics industry and the growing need for advanced energy storage solutions have driven the quest for rechargeable batteries with improved capacity and prolonged lifetimes. In this context, significant attention has been directed towards the exploration of two-dimensional (2D) materials, particularly carbon nanosheets such as Graphdiyne, owing to their compelling electrical, optical, mechanical, and chemical properties. The recent achievement in producing pyrazinoquinoxaline graphdiyne (PQ-GDY) nanosheets, distinguished by their remarkable stability and exceptional physical properties, has ignited our research curiosity, prompting an exploration of their potential suitability as anode materials for lithium (Li), sodium (Na), calcium (Ca), and magnesium (Mg) ion batteries. This investigation is conducted using first-principle electronic structure simulations. Drawing from our rigorous theoretical analysis, pyrazinoquinoxaline graphdiyne (PQ-GDY) has demonstrated favorable electrode properties, positioning it as a promising candidate for potential utilization in Li, Na, and Ca ion batteries. Notably, the pyrazinoquinoxaline graphdiyne rectangular (PQ-GDY-Rec) material demonstrates remarkable storage capacities for Li , Na , and Ca ions, reaching values of 1938 m A h / g , 1716 m A h / g , and 830.60 m A h / g , respectively. These findings position PQ-GDY-Rec as a highly promising material for application in metal-ion batteries, suggesting new avenues for the advancement of rechargeable batteries with significantly enhanced storage capabilities. • Pyrazinoquinoxaline graphdiyne's electrode properties make it a promising candidate for Li, Na, Ca ion batteries. • Pyrazinoquinoxaline graphdiyne rectangle shows remarkable ion storage for Li, Na, Ca ions. • The study implies enhanced anode electrodes through Li/Na binding, but Mg insertion seems challenging. • The PQ-GDY-Re monolayer, interfaced with Li, Na, and Ca adatoms, exhibits exceptional structural resilience. • OCV provides insights on Li/Na adatom adsorption limit on PQ-GDY-REC nanosheet surface. [ABSTRACT FROM AUTHOR]

The efficiency of lithium-ion batteries (LIBs) depends upon anode materials possessing high capacity. In present study, we investigate boron carbide cone anode (BCC) for LIBs. The first-principles density functional theory (DFT) method is used to design anode materials based on BCC for application in LIBs. We found that the BCC shows negative Li adsorption energies. Our results also revealed the fast diffusions of Li ion on the BCC with the small energy barrier of 0.34 eV. The storage capacity of BCC system rank among the highest capacity of anodes for LIBs, with value of 785 mAh/g. The low average open-circuit voltage (OCV) value of BCC system indicates that this anode can handle a large operating voltage in LIBs. [ABSTRACT FROM AUTHOR]

The non-fullerene acceptor (NFA) chromophores have sparked scientific and economic interest, due to their rapid advancements in power conversion efficiencies. Therefore, a series of new chlorothiazole based compounds (STM1-STM6) with A1–π–A2–π–A1 configuration was designed using reference chromophore (STMR). Structural modifications were made via incorporating selenophene and extended acceptor units, to enhance photovoltaic response in the designed materials. Density functional theory/time dependent-density functional theory (DFT/TD-DFT) calculations were executed at M06/6-311G (d,p) level to investigate key electronic and photovoltaic properties of STM1-STM6. So, various analyses such as UV–Visible, frontier molecular orbitals (FMOs), transition density matrix (TDM), density of states (DOS), open circuit voltage (V oc) and binding energy (E b) were conducted to comprehend the photovoltaic properties. The designing in structural aspects with terminal acceptors and π-linker induced a reduction in energy gaps (ΔE = 2.078–2.237 eV) with an enhancement in the bathochromic shift (λ max = 744.650–798.250 nm in chloroform) than reference compound. A higher exciton dissociation rate was observed in all the compounds due to lower binding energy values (E b = 0.525–0.572 eV). Additionally, TDM and DOS findings further endorsed the effective charge delocalization from HOMO to LUMO. Among all the examined compounds, STM3 exhibited the smallest band gap (2.078 eV), highest absorption maxima (798.250 nm), and the lowest exciton binding energy (0.525 eV), indicating significant electronic properties. Moreover, V oc analysis was conducted with respect to HOMO PBDBT -LUMO acceptor for all the designed chromophores; consequently, STM2 demonstrated a substantial V oc value of 1.647 V. Similarly, electron hole analysis was also conducted and significant electron and hole density was observed in all the investigated compounds, especially in STM2. The entitled compounds with photovoltaic potential would be considered as promising materials for the development of solar energy devices. [ABSTRACT FROM AUTHOR]

Open-circuit voltage (V OC) losses due to various recombination mechanisms are well-recognized limitations towards high-performance solar cells. Thin film Cu(In,Ga)Se 2 (CIGSe)-based solar cells have been well-developed and commercially used in the photovoltaic community due to their high power conversion efficiency (PCE) with high chemical stability and cost-effectiveness. Recently, numerous works on modification of the CIGSe/buffer band alignment and alkali post-deposition treatment on CIGSe have shown obvious enhancement of the solar cell efficiency. In this work, we explore the effects of subgap absorption driven by quasi-Fermi level splitting (QFLS) and Urbach tail (E U) states in CIGSe on V OC losses. In particular, we take all subgap absorption contributions into account to precisely fit the full photoluminescence (PL) spectra and obtain the QFLS and E U energies using an integrated model. We found that for CIGSe films with different Ga contents, the model can fit the PL spectra perfectly, which allows the extraction of reliable values of QFLS and E U. Using these values, we further calculated the V OC in both the SQ and radiative limit, as well as the non-radiative loss due to subgap absorption. We also showed that sample with a larger QFLS and a lower E U exhibits a smaller V OC loss and thus a higher PCE. Although the effects of QFLS on V OC is much smaller than Urbach tail, a more accurate estimation of V OC loss due to non-radiative recombination can be achieved when QFLS is considered. These results shed light on the origin of V OC losses in solar cells, which is potentially useful for the advancement of PV technology. • Cu(In,Ga)Se 2 solar cells were fabricated by 3-stage co-evaporation. • Urbach tail energy and QFLS energy are extracted by fitting the full PL spectrum. • Low Urbach tail energy and large QFLS energy minimize the V OC loss. • Accurate non-radiative V OC loss can be calculated when QFLS is considered. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hexagonal boron nitride quantum dots are studied for organic solar cell applications. • A significant reduction of the energy gap with the concomitant red shifting of the absorption spectra was achieved in h-BNQD-SCH 3. • The light-harvesting efficiency near unity was achieved after an increase in the intensity of absorption intensity. Within this research, the possibility of using hexagonal boron nitride quantum dots (HBNQDs) and edge-functionalized h-BNQDs (EFHBNQDs) as hole transport materials (HTMs) was explored in perovskite solar cells (PVSCs). The performance, hole mobility (HM), hole reorganization energy (λ h), exciton binding energy (E b), light harvesting efficiency (LHE) and solubility of these HTMs were investigated to determine their suitability. Based on the results, in contrast with Spiro-OMeTAD that is commonly used as an HTM in PVSCs, these HTMs had a greater HM. Also, their fill factor and open circuit voltage were computed to be suitable, similar to those of MAPbI 3 -based PVSCs. Thanks to their high performance, small λ h and high solubility, H-BNQD-SCH 3 were considered to be the most ideal HTMs. [ABSTRACT FROM AUTHOR]

First-principles density functional theory (DFT) was adopted for investigating the influence of adatoms (S, Si, Al) upon the graphene quantum dot functionalized with the carboxyl group (CO 2 H-GQD) in order to find novel materials due to unique optical (redshift) and electronic (lower bandgap) properties for utilization in quantum dot solar cells (QDSCs). For the sake of examining the alteration in the electronic attributes due to the insertion of adatoms, the bandgaps, the LUMO and the HOMO were examined using the density functional B3LYP and the basis set 6-31G. For the sake of examining the charge separation and electron injection in the un-doped and doped CO 2 H-GQD, we scrutinized the charge transport, molecular electrostatic potential (MESP) and the binding mechanism. The optical attributes demonstrated a broad spectrum in the visible range favorable towards harvesting solar light. We also investigated the parameters of solar cells such as efficiency (η), short circuit current density (J sc), fill factor (FF), open circuit voltage (V oc) in order for the sake of examining the use of adatom-doped CO 2 H-GQD in QDSCs. There was an increase in the efficiency of S-doped, Si-doped, and Al-doped CO 2 H-GQD. Doping the CO 2 H-GQD led to the maximum efficiency since electron donating nature was more, thereby injecting more electrons in the surface of TiO 2. The results demonstrated that such GQD-based sensitizers can be used effectively in QDSCs. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents a non-iterative maximum power point tracking (MPPT) technique for solar photovoltaic (PV) panels. The non-iterative MPPT is realised using online measured open circuit voltage and short circuit current along with the Fill Factor extracted from the datasheet parameters of PV panel. The proposed MPPT returns a power reference, which is directly used in the inverter control loop. This non-iterative MPPT algorithm is implemented in a single-stage three-phase inverter feeding power to grid with a hysteresis current controller. Restructuring of the Converter power circuit is proposed to facilitate the online measurements of the dynamic panel values. DC link energy storage is provided to maintain power delivery to grid during momentary disconnection of the panel due to measurement. The design procedure and selection of all the ancillary components for the restructured power circuit are presented in detail. The system implemented in hardware for a power rating of 0.5 kW is tested under steady and dynamic states of possible irradiance including partial shading. The proposed non-iterative MPPT is found to be far superior in performance to the regular iterative MPPTs. [ABSTRACT FROM AUTHOR]

Natural gas is one of the most important fuels for solid oxide fuel cell (SOFC). The relationships among the reactions of methane over the nickel-based anode, fuel compositions, carbon deposition, electromotive force (EMF) and open circuit voltage (OCV) of SOFC are investigated in this work. With the increase of temperature, EMF and OCV of SOFC decrease gradually when the cell uses humidified hydrogen as fuel. Reactivity of methane increases gradually with the increase of temperature, which can affect the EMF and OCV of SOFC. When the humidified mixture of nitrogen and methane is used as the fuel, the EMF and OCV of SOFC increase gradually with the increase of temperature. EMF and OCV of SOFC with humidified mixture of hydrogen and methane (M CH4 : M H2 : M H2O = 12.2: 85.3: 2.5) as fuel decrease gradually with the increase of temperature when the temperature is lower than 873 K, which is similar to that with humidified hydrogen as fuel. While when the temperature is higher than 923 K, the EMF and OCV of SOFC with humidified mixture of hydrogen and methane as fuel increase gradually with the increase of temperature, which is similar to that with humidified mixture of nitrogen and methane as fuel. OCV of SOFC is mainly affected by thermodynamic equilibriums for methane-fuelled SOFC when the anode activity is high enough, which is close to the EMF calculated according to the thermodynamic equilibriums. While with the increase of carbon deposition, the anode activity decreases apparently and the OCV of SOFC also decreases apparently, which shows that the OCV is affected by the anode activity for methane-fuelled SOFC when the anode activity is low. • OCV of SOFC is mainly affected by thermodynamic equilibrium at high anode activity. • For H 2 and CH4 mixed fuel, OCV change is similar to that of H 2 at low temperature. • OCV change for H 2 and CH 4 mixed fuel is similar to that of CH 4 at high temperature. • Carbon deposition can lead to the decreases of anode activity and OCV of SOFC. • OCV is affected by anode activity for methane-fuelled SOFC at low anode activity. [ABSTRACT FROM AUTHOR]

Researchers are presently concentrating on utilization of fullerene-free organic chromophores as efficient materials for solar cells to align with the demands of modern technology. Keeping in view the importance of non-fullerene, a group of V-shape naphthalene diimide-based chromophores (MBPV1 - MBPV5) for OSCs with A 2 – π – A 1 – D – π – A 2 framework were designed by modifying their π -spacer and A 1 acceptor. Analyses like absorption properties (UV-Vis), open circuit voltage (V oc), frontier molecular orbital (FMOs), transition density matrix (TDM), the density of state (DOS), and power conversion efficiencies (PCEs) were executed at MPW1PW91/6–31(d,p) functional, to study the key electronic properties of the naphthalene based compounds. Structural modeling with π-spacer and acceptor moieties causes a reduction in band gap with broader absorption spectra particularly in MBPV4 (ΔE = 2.011 eV and λ max =682.996 nm). An effective transfer of charge towards LUMO from HOMO orbital was studied which was further supported by DOS and TDMs heat maps. Further, open circuit voltage (V oc) analysis was performed with respect of HOMO P3HT -LUMO acceptor and among all the tailored chromophore, MBPV4 exhibited a significant V oc value: 2.296 V with a power conversion efficiency of 31.96%. The designed chromophores demonstrated favorable optoelectronic behavior. Hence, this research illustrates that the engineered chromophores with electron withdrawing units may offer a favorable option for constructing advanced organic solar cells in upcoming applications. [Display omitted] • Designing of naphthalene diimide based chromophores for OSCs. • Structural modeling with π -spacer and acceptor moieties. • Exploration of photovoltaic behavior of designed chromophores. • Study of key electronic properties at MPW1PW91/6-31 G (d,p) functional. • Utilization of TD-DFT approach for FMOs and UV-Vis analyses. [ABSTRACT FROM AUTHOR]

[Display omitted] • New eco-friendly hydrogels, containing the natural polysaccharide galactomannan and Zn-based nanoparticle are reported. • DSSCs devices built with the new hydrogel as QSE, exhibit an impressively high open circuit voltage and state-of-the art PCE. • The best Zn-based hydrogel devices also reach high values of Average Visible Transmittance and Light Utilization Efficiency. In the present work, we implement environmentally friendly water-based Quasi-Solid Electrolytes (QSE) for Dye Sensitized Solar Cells (DSSCs), displaying an unprecedent open circuit voltage (V OC) as high as 750 mV. The production of the hydrogel for QSE-DSSCs is achieved by exploiting the concept of fully green design and fabrication, through the selection of components such as the natural polysaccharide galactomannan (GM), biocompatible zinc salts, and the employment of eco-friendly synthetic procedures to produce the hybrid gelating agents. In the process, moderate temperature (<40 °C), only aqueous solutions are employed, and, at most, ethanol is used in some phases of the procedure. Depending on the type of the initial salt, either zinc hydroxysulfate lamellae or zinc oxide nanoparticles are created within the gel matrix, with a more extended nanoporous structure in the latter case. The nanostructures and the gels are investigated by multiple techniques, including X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Upon ensuing addition of I-/I 3 - redox mediator and assembling of the device, state-of-the-art aqueous QSE-DSSCs are achieved. The latter couples a 2 % efficiency (limited by charge diffusion as proved by Electrochemical Impedance Spectroscopy) with a good Average Visible Transmittance (AVT), and Light Utilization Efficiency (LUE), a couple of coveted features in wave-selective or semi-transparent devices. Finally, Linear Response-Time Dependent DFT (LR-TDDFT) simulations are carried out on a model iodine/iodide layered zinc hydroxy sulphate structure towards a better understanding of the mechanism responsible for the high AVT. [ABSTRACT FROM AUTHOR]

Relaxation voltage (RV) of a battery is informative since it not only approximates open circuit voltage (OCV) as time evolves, but it is also related to the battery's state of charge (SOC) and state of health (SOH). Given that RV is easy to obtain by simply stopping a battery's operation, it is an excellent data source to estimate battery states. Without using complete RV history whose acquisition is time-consuming and hinders further applications, this study uses Gaussian process regression model with the input of only a small portion of RV to rapidly and simultaneously estimate the OCV and SOH of a battery. Various input lengths are tested, showing that using only 30-s RV data, the mean absolute error (MAE) for predicting OCV is 2.99 mV, and that for estimating SOH is 2.76%. As soon as the voltage difference is also treated as the model input, we find that the MAE for the SOH estimation is further declined to about 1.83%. Compared to previous methods which either estimate single battery state or require minutes of RV data for estimation, the current model is able to perform multiple battery estimation using only first tens of seconds of data. • The close relation between RV and OCV (or SOH) is clarified. • Relaxation voltage can be used to simultaneously estimate OCV and SOH. • OCV and SOH can be accurately predicted in tens of seconds with RV. • Various input data lengths, sampling intervals, and ML models are extensively discussed. [ABSTRACT FROM AUTHOR]

• The highest efficiency for a 4H -pyranylidene was obtained. • High Open Circuit Voltage (Voc) without the use of additives. • An off-plane thiophene ring minimizes aggregate formation. • The incorporation of an additional thiophene ring increases stability of the dyes. Five sensitizers bearing a 4H -pyranylidene moiety have been synthesized. The incorporation of a thiophene ring (with different substituents in its position 5), in the exocyclic double bond of the previously reported SFO-346 , leads to twisted structures of type 2D-π-A and D–(π–A) 2 that minimize the π-π stacking of the dyes on the photoanode. Theoretical calculations confirm the tridimensional structure of the molecules. Moreover, the different electronic nature and bulkiness of the substituents modulate the optical and electrochemical properties of the sensitizers. A power conversion efficiency of 7.68% was obtained when the thiophene was substituted with a tert -butyl group (dye 16), the highest value reported, so far, for dyes based on a 4H -pyranylidene. That efficiency is mainly due to the high open circuit voltage observed (0.729 V) without using anti-aggregating additives. [ABSTRACT FROM AUTHOR]

• The study investigated the optimum GAC dosage in BeCC by evaluating its COD, sulfide removal and throughout 30 days of operation. • Optimum GAC dosage was 10 g with highest COD and sulfide removal of 97.56% and 96.25%, respectively and highest OCV of 583 mV. Increasing GAC dosage from 0 g to 10 g increased the BeCC performance whereas higher than 10 g of GAC dosage deteriorated the BeCC performance. • The dominant bacteria attached on the GAC was Klebsiella Oxytoca identified by biochemical method. The study is to treat spent caustic wastewater by using bioelectrochemical cell (BeCC) integrated with Granular Activated Carbon (GAC) as the bacterial attachment medium. BeCC is a bioelectrochemical reactor which employed microorganisms for substrate degradation, while also capable in producing energy. The study investigated the optimum GAC dosage in BeCC whereby it was tested at 0 g (blank) to 25 g of GAC and its performance in terms of Chemical Oxygen Demand (COD) and sulfide removal and open circuit voltage (OCV) were assessed throughout 30 days of operation. From the study, GAC dosage of 10 g was the optimum GAC dosage with the highest COD and sulfide removal of 97.56% and 96.25%, respectively and highest voltage of 583 mV. Comparing the optimum BeCC performance with the blank, the result demonstrated 16% and 25% higher in COD and sulfide removal, respectively with increment of OCV from 115.7 mV to 583 mV. The biomass characteristics at different GAC dosage were indicated by the mixed liquor suspended solid (MLSS), mixed liquor volatile suspended solid (MLVSS), biomass extracellular polymeric substance (EPS) and sludge volume index (SVI). It is found that the dominant bacteria attached on the GAC was Klebsiella oxytoca identified by biochemical identification method. [ABSTRACT FROM AUTHOR]

Open circuit voltage of a photovoltaic system, in general, is constrained by the Schottky barrier (SB) heights formed at the electrodes. Here, the SB heights which are inhomogeneous in nature at the anode-semiconductor junction of a donor-acceptor-acceptor molecule, 2-[(7-(4-[N,N-bis(4-methylphenyl)amino]phenyl)-2,1,3-benzothia-diazol-4-yl)methylene] propane-dinitrile (DTDCPB), mixed with C 70 as a bulk heterojunction have been studied thoroughly by inserting an insulating layer of MoO 3 with different thicknesses (6 nm, 12 nm, 18 nm) and measuring the current density-voltage (J-V) and capacitance-voltage (C–V) characteristics of the photovoltaics under a large temperature range of 100K–300 K for proper estimation of open circuit voltage (V oc). Experimental results reveal a linear inverse temperature dependence of SB heights in the whole temperature range. The mismatch in the extracted values of SB heights from the independent measurements of J-V and C–V vanishes under the consideration of non-linear temperature dependence of built-in potential (V bi) leading to the legitimate prediction of V oc. The inhomogeneous Schottky barrier formed at the interface of the anode and the active layer of OPV limits the V oc of the device as revealed by the nonlinear temperature dependence of the built-in voltage estimated independently by C-V and J-V measurements. Image 1 • Schottky barrier formed at the anode of a small molecular photovoltaic was studied. • A varied MoO 3 insulating layer was inserted in between the anode and active layer. • J-V and C–V measurements were performed at low temperatures (100K – 300K). • A linear inverse temperature dependence of Schottky barrier heights was revealed. • A non-linear temperature dependence of built-in potential was observed. [ABSTRACT FROM AUTHOR]

It is very important for the battery management system of electric vehicles to estimate the battery state of charge accurately and to achieve the on-line updating of the battery model parameters. In this paper, the estimation of the open circuit voltage is converted to the estimation of the open circuit voltage fitting parameters, the fast time-varying parameter open circuit voltage is converted into several slowly time-varying parameters. A multi-scale parameter adaptive method based on dual Kalman filters is developed. The multi-scale estimation of the battery state of charge and all parameters including open circuit voltage can be achieved. And the parameter adjustment method of dual extended Kalman filters in estimating multiple parameters is given. The experimental results show that the accuracy of the algorithm is improved by adding the estimation of the open circuit voltage. The proposed method can reduce the influence of the initial state error on the algorithm, and improve the robustness of the algorithm. • A multi-scale parameter adaptive method is developed for battery system. • The proposed approach estimate OCV by estimating OCV fitting parameters. • The proposed approach can estimate all battery parameters and SOC by different scales. • The method of adjusting parameters of dual extended Kalman filters is given. [ABSTRACT FROM AUTHOR]

There is great interest in finding suitable electrode materials for metal-ion batteries with good performance, low diffusion barriers and high capacity. Using the art of density functional theory (DFT), we systematically evaluated the possibility of planar carbon haeckelite structures (h567, r57, and o567) for a suitable anode in Lithium-ion batteries (LIBs). Our results show that haeckelites possess significant structural, mechanical, and electronic stability with high metallicity for LIB anode applications. Especially, the haeckelite h567 shows improved specific capacity (Li 1. 875 C 6 ∼ 697 mAhg − 1) compared to LiC 6 graphite due to the negative Li binding energy without clustering of Li atoms. In addition, it is worth noticing that the low open-circuit voltage (<0.30 V) and Li diffusion energy barrier (E a < 0.35 eV) of the haeckelite h567comparable to that of the graphite is beneficial to the overall performance of the LIBs. Based on the excellent electronic structure, superior Li mobility, extremely high in-plane stiffness, low open-circuit voltage, and high specific capacity, haeckelite h567 can be a promising anode material for the low-cost and high-performance LIBs. Image 1 [ABSTRACT FROM AUTHOR]

Highlights • Development and investigation of a new direct ammonia fuel cell stack. • Open circuit voltage is found to be 1249 ± 37.5 mV. • Peak power density is observed to be 13.4 ± 0.4 W m−2. • Energy and exergy efficiencies are found to be 52.4 ± 1.6% and 49.3 ± 1.6% respectively. Abstract In the present study, the experimental investigation and performance evaluation of a newly developed direct type ammonia fuel cell stack are performed. A solid anion exchange membrane electrolyte is also utilized. The performances of a single-cell and a 5-cell stack are investigated through thermodynamic efficiencies. The open circuit voltages for a single cell and 5-cell stack are obtained as 280 ± 8 mV and 1249 ± 37.5 mV respectively. Furthermore, the peak power densities are found as 6.4 ± 0.2 W m−2 and 13.4 ± 0.4 W m−2 for a single-cell and a 5-cell stack respectively. Moreover, the effects of varying humidifier temperatures on their efficiencies are studied, and hence increasing humidifier temperatures are found to provide higher efficiencies. Both energetic and exergetic efficiencies at the peak power density are determined to be 52.4 ± 1.6% and 49.3 ± 1.6% respectively under the ambient conditions considered. [ABSTRACT FROM AUTHOR]

Highlights • V oc in organic solar cells is quantified by considering band bending at the heterojunction. • The non intentional doping in organic heterojunctions determines band bending. • Fullerene based organic solar cells form an abrupt p-n heterojunction. • The dominant recombination determining Voc occurs at the heterojunction. Abstract By using electrical characterization and classical solid state semiconductor device theory, we demonstrate that the open circuit voltage (V oc) in organic solar cells based on non-intentional doped semiconductors is fundamentally limited by the built-in potential (V bi) originated at a donor-acceptor abrupt (p-n++) heterojunction in case of selective contacts. Our analysis is validated using P3HT:PCBM devices fabricated in our research group. We also demonstrate that such a result can be generalized using data already reported in literature for fullerene-based solar cells. Finally, we show that the dependence of V oc on the device contacts can be understood in terms of the potential barriers formed by the Fermi level alignment of semiconductors at the heterojunction and at the Schottky junctions. [ABSTRACT FROM AUTHOR]

Abstract Battery state of charge is a crucial indicator of battery management systems since an accurate estimated state of charge is critical to ensure the safety and reliability of the battery. However, polarization during the discharge process can affect the dischargeable capacity in the state-of-charge definition. Moreover, a nonlinear drop of the state-of-charge may lead to misjudgment of the remaining-dischargeable-time. To address these issues, the voltage-based state of charge is defined to reduce the effects of polarization and reflect the upper bound of the remaining capacity of the battery. This paper proposes a particle filter based open circuit voltage online estimation method to achieve the voltage-based state of charge. On this basis, an open-loop remaining-dischargeable-time prediction algorithm using the voltage-based state of charge is introduced. Static and dynamic tests are presented to identify battery model parameters as well as the relationship between available capacity and voltage-based state of charge. Two definitions of the state of charge definition are applied in the prognostics architecture. Results are compared and evaluated concerning the accuracy of the voltage tracking and the relative error of the remaining-dischargeable-time prediction. The comparison results show that prognostics via voltage-based state of charge has a lower prediction relative error under different current and temperature conditions. Therefore, the voltage-based state of charge is more suitable for the remaining-dischargeable-time forecast. Highlights • The difference between two kinds of SOC definition is compared and analyzed. • The voltage-based SOC is estimated via PF based OCV estimation and OCV-SOC curve. • An open-loop RDT prediction framework based on SOC estimation is presented. • The accuracy of the prognostics method is validated under different conditions. [ABSTRACT FROM AUTHOR]

Abstract The state-of-charge (SOC) estimation method currently ignores the measurement error caused by the Battery Management System (BMS). In this paper, the characteristic of LiFePO 4 battery is deeply studied to explore the relationship between open-circuit-voltage (OCV) and SOC. By the analysis of the characteristic of the curve, the results show that the curve does not change with the battery aging by the capacity correction. Meanwhile, the feature of the charging voltage curve is also analyzed. It is pointed out that the ohmic internal resistance and capacity can be obtained by the transformation of the charging voltage curve, which reduces the workload of the dual extended kalman filter (DEKF) algorithm. Based on the DEKF algorithm, the SOC under constant current and dynamic discharge conditions are estimated. The results show that the estimation error is within 3%. The influence of battery voltage and current measurement noise on the estimation accuracy of the SOC is then analyzed. It is found that the measurement noise increases the SOC estimation deviation. Finally, the open circuit voltage in measurement equation is replaced by the charging voltage. And a new method of combining DEKF algorithm and charging voltage curve for SOC estimation is proposed. The results of the experiments under constant current and dynamic discharge conditions show that the proposed method can eliminate the measurement noise and ensure the accuracy of SOC estimation. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT computations were performed on graphene quantum dots (GQDs). • GQDs doped with halogen adatoms were studied for quantum dot-sensitized solar cell. • A significant reduction of the E g with the concomitant red shifting of the absorption spectra was achieved by Br atom doping. • The LHE near unity was achieved after an increase in the intensity of absorption intensity. This research has been conducted to find new, high-performing, safe, and suitable materials for use in quantum dot solar cells (QDSCs). Specifically, impact of halogen adatoms (Br, Cl, and F) on carboxyl edge-functionalized graphene quantum dot (CO 2 H-GQD) has been investigated employing DFT-based first-principles computations. We analyzed energy gaps (E g), LUMO, and HOMO to determine how the foreign atom affects electronic features of material, employing hybrid functional B3LYP with a 6-31G basis set. In order to investigate charge separation and electron injection in both doped and undoped CO 2 H-GQD, we examined charge transfer (CT), molecular electrostatic potential (MESP), and binding mechanism. Optical attributes also indicate a wide spectrum in visible range, making it suitable for harvesting solar light. Furthermore, we evaluated solar cell parameters, including efficiency (η), short circuit current density (J sc), fill factor (FF), and open circuit voltage (V oc) to assess potential usage of adatom-doped CO 2 H-GQD in quantum dot solar cell. Subsequent to Br, Cl, and F substitutional doping, value of η for CO 2 H-GQD increased. In case of F doping, we achieved maximum η, which has electron-donating nature and a larger radius, allowing it to inject more electrons into titanium dioxide (TiO 2) surface. Based on our research, we have determined that these recently discovered sensitizers built upon GQD exhibit considerable potential for use in QDSCs. [ABSTRACT FROM AUTHOR]

The optimization of present multijunction junction solar cells and the development of new concepts is an important task for modem photovoltaics. For its development, special attention should be paid to the potential quality of photoactive p-n junctions, as well as to their properties when operating at various temperatures. The present research has shown that for two-diode model of the p-n junction it is convenient to use current invariants J z1 and J z2 for calculating the diffusion and recombination saturation dark currents J 01 and J 02 for p-n junctions based on semiconductor materials with any band-gap energy. It has been experimentally found that J z1 and J z2 are constants relating the semiconductor material band gap energy and temperature with J 01 and J 02. It has also been shown that J z1 and J z2 determine the open circuit voltage and the value of voltage offset W OC. Current invariant suggested to be useful tool for evaluating the quality of a p-n junction and for modeling the characteristics of solar cells because it allows making calculations taking into account both main mechanisms of current flow and the operating temperature of the device. • Current invariant is a new approach for multijunction solar cell optimization. • Current invariant allows calculating dependence of saturation currents on band gap. • The approach takes into account both the diffusion and recombination current flows. • Experimentally shown that current invariant value doesn't depend on temperature. • Voltage offset linearly depends on temperature and is about 0.46 V at T = 300K [ABSTRACT FROM AUTHOR]

[Display omitted] • Investigating Ca storage mechanism and properties of BeP 2 was calculated. • Ca has low diffusion barrier and high capacity on BeP 2 surface. • The interface electronic behavior of BeP 2 enhance the adsorption of Ca. One of the efficient methods for boosting the energy density of modern metal-ion batteries is finding electrode materials with high performance. Before and following the adhesion of metal ions, a BeP 2 monolayer (BeP 2 ML) has intrinsic metallicity and high conductance. The first-principles DFT computations demonstrate that BeP 2 ML is one of the encouraging electrode materials for Ca-ion batteries (CIBs). Furthermore, the theoretical capacity of a fully Ca phase Ca 2 BeP 2 for BeP 2 ML was high (629 mA h g−1) having an additional calcium ion layer, which outperformed other two-dimensional ones reported in the literature. Additionally, after the full adhesion of metal ions, BeP 2 ML exhibited a surprisingly low open circuit voltage and diffusion barrier (0.24 V). The present piece of research can provide insights into exploring new BeP 2 ML-type electrode materials for CIBs. [ABSTRACT FROM AUTHOR]

The simulations of π-extended systems (TQ31-TQ35) through the quantum mechanical model by the structural amendment of model TQ3R based on quinoxaline core through peripheral acceptors via thiophene bridging were conducted at PBEPBE/6-31G (d, p) level. The geometric constraints were investigated through optimization to study optoelectronic and photovoltaic parameters. The energy gap of novel molecules found to be minimized up to 0.16 eV obtained from FMO analysis possessed high charge transfer. The different reactivity parameters like ionization potential, softness, electronegativity, and electron affinity proclaimed reactivity as well as stability of all the studied systems. TD-DFT calculations declared a high absorption maximum for all the novel systems at longer wavelengths up to 1080 nm greater than model TQ3R (490 nm) in dichloromethane solvent. Low excitation energies (up to 0.23 eV) were found to be favorable for competent charge transference and elevated dipole moment (up to15.23 D) of all the newly amended molecules aided efficient solvation effect and charge separation. DOS study possessed effective contribution of the bridge, donor, as well as acceptor fragments of the novel molecular systems in HOMO to LUMO charge transfer. TDM plots exhibited high charge transition locations for electronic transitions by light absorption. Lower reorganization energy for the hole as well as for electron proclaimed efficient exciton dissociation and high charge mobility while effective values of V OC (open circuit voltage) and FF (fill factor) proclaimed increasing PCE (power conversion efficiency) of photovoltaic devices. Outcomes of the whole consideration revealed that all the innovative chromophores (TQ31-TQ35) are excellent contenders for the assembly of organic photovoltaics. [Display omitted] • Quinoxaline-based molecules were premeditated by structural amendment of TQ3. • FMO analysis exposed minimum HOMO-LUMO energy gap causing high charge transfer. • Designed novel molecules exhibited maximum absorption in visible and near IR regions up to 1080 nm. • Low values of reorganization energies for electron and hole exposed high charge mobility. [ABSTRACT FROM AUTHOR]

Minimizing the energy loss and improving the open circuit voltage of organic solar cells is still a primary concern for scientists working in this field. With the aim to enhance the photovoltaic performance of organic solar cells by minimizing energy loss and improving open circuit voltage, seven new acceptor molecules (LC1-LC7) are presented in this work. These molecules are designed by modifying the terminal acceptors of pre-existed "LC81" molecule based on an indacinodithiophene (IDT) fused core. The end-group modification approach is very fruitful in ameliorating the efficacy and optoelectric behavior of OSCs. The newly developed molecules presented remarkable improvements in performance-related parameters and optoelectronic properties. Among all designed molecules, LC7 exhibited the highest absorption maxima (λ max = 869 nm) with the lowest band-gap (1.79 eV), lowest excitation energy (E x = 1.42 eV), lowest binding energy, and highest excited state lifetime (0.41 ns). The newly designed molecules LC2, LC3, and LC4 exhibited remarkably improved Voc that was 1.84 eV, 1.82 eV, and 1.79 eV accordingly, compared to the LC81 molecule with V oc of 1.74 eV LC2 molecule showed significant improvement in fill factor compared to the previously presented LC81 molecule. LC2, LC6, and LC7 showed a remarkable reduction in energy loss by showing E loss values of 0.26 eV, 0.18 eV, and 0.25 eV than LC81 molecule (0.37 eV). These findings validate the supremacy of these developed molecules (especially LC2) as potential components of future OSCs. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to favorable future use of electrochemical energy storage systems in portable electronic devices, these systems have received much attention. Employing these systems in "smart" clothes equipped with piezoelectric pieces to gain energy from body movement and roll-up displays is promising. Nevertheless, further development of these technologies is a significant challenge due to lack of appropriate battery electrodes that supply desirable electrochemical performance. 2D flexible and light materials with remarkable chemical and physical attributes such as acceptable conductivity, high surface metal diffusivity, hydrophilic surfaces, and mechanical strengths were introduced as potential options for battery electrodes. In present research, 2D orthorhombic di-boron di-nitride monolayer (o-B 2 N 2) as a novel 2D boron nitride allotrope has been investigated. Systematically, various impacting factors like their electrochemical and electronic features (theoretical capacity, equilibrium voltage, binding strength, etc.) were investigated. It is noteworthy that specific capacity of K-ion batteries (KIBs) reaches 2347 mAh.g-1. In addition, the existence of o-B 2 N 2 ring accelerates the diffusion of K-ions, and diffusion barriers are 0.14 eV. Mean open circuit voltage (OCV) and low diffusion barrier of o-B 2 N 2 monolayer guarantee long service life and fast charging/discharging for practical purposes. Based on results, monolayer o-B 2 N 2 is proper as a high-performance negative electrode material in KIBs. [ABSTRACT FROM AUTHOR]

Currently, non-fullerene-based acceptors in organic solar cells (OSCs) have gained significant attention of researchers owing to their particular characteristics. Herein, new W-shaped dithiophene based acceptor chromophores (D1 - D8) possessing A-π-D-π-A configuration were fabricated via end group structural tailoring by utilizing promising acceptors groups. To probe the effect of end group manipulation on the optoelectronic properties of entitled chromophores, density functional theory/time-dependent density functional theory (DFT/TD-DFT) calculations were accommodated at B3LYP/6–311 G(d,p) functional. Frontier molecular orbitals (FMOs) findings revealed that the derivatives (D1-D8) exhibited narrow band gap (1.191–2.110 eV) than that of reference chromophore (R =2.380 eV) due to efficient acceptor moieties. UV–Vis data collected in chloroform solvent revealed that λ max values of D1-D8 were existed in visible region (738.6–692.5 nm). Moreover, D2 and D4 proves to be the best chromophores exhibiting least band gap of 1.191 and 2.000 eV and broad absorption spectrum i.e. , 738.573 and 735.986 nm , respectively. Among all the designed compounds, D2 , D3 , D4 and D6 manifested higher open circuit voltage values. Theoretical analysis disclosed that all the designed molecules exhibited almost comparable results with each other. Nevertheless, D2 and D4 provided significant findings and can be utilized as best candidate for use in optoelectronic devices. • Structural Modeling of Dithiophene-Based Chromophores (D2-D9) to explore their Photovoltaic Properties. • Study of key electronic properties at B3LYP/6–311 G(d,p) level of DFT. • Time dependent Density functional theory (TD-DFT) will be performed for frontier molecular orbitals (FMOs) and UV-Vis analyses. • Validation and application of designed compounds is explored by investigating photovoltaic behavior. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries with silicon/graphite anodes have the potential to deliver high theoretical capacity. However, these electrodes exhibit significant hysteresis, which presents challenges in accurately estimating the open-circuit potentials (OCP) of the electrodes within a physics-based model. This paper proposes a method to establish the relationship between the electrode OCP and stoichiometry. Galvanostatic intermittent titration technique (GITT) tests are performed on half-cells to measure the charge and discharge OCP. To account for hysteresis, a hysteresis factor is defined to balance the lithiation and de-lithiation OCP. The estimated open-circuit voltage (OCV) of the full-cell is obtained by subtracting the anode OCP from the cathode OCP. The OCP and hysteresis factor are then optimized by minimizing the error between the measured OCV and the estimated OCV. Two different OCV test methods, namely the incremental method and C/30 galvanostatic method, are compared. The OCV estimation for fresh cells shows good agreement with experimental values, with root-mean-square errors (RMSEs) below 6.682 mV. To evaluate the effectiveness of the obtained OCPs in the full-cell model, the optimized OCPs are incorporated into the physics-based model. Under the Hybrid Pulse Power Characterization (HPPC) test, the electrochemical model utilizing the optimized OCP with the incremental OCV and C/30 galvanostatic OCV exhibits RMSEs of 10.587 mV and 11.016 mV, respectively, in predicting the cell voltage. Finally, the OCP identification method is assessed with cells at different aging states. The OCV predictions for degraded cells maintain RMSEs below 9.074 mV, thus validating the effectiveness of the developed OCP estimation method. • Open-circuit-potential of Silicon/graphite composite electrode is accurately determined. • Two open-circuit-voltage test methods are compared. • Obtained open-circuit-potential is applied to the pseudo-two-dimensional model. • The identified open-circuit-potential are validated against cells at different aging conditions. [ABSTRACT FROM AUTHOR]

Accurate estimation of the state-of-charge (SOC) is crucial for efficient and safe battery applications. However, existing SOC estimation methods fail to provide accurate SOC estimation for LiFePO 4 batteries that have a flat voltage-SOC relationship. The analysis of the voltage-SOC characteristics shows that the failure of the present model-based methods can be ascribed to their inability to simultaneously accommodate the differences in voltage characteristics between different open-circuit-voltage (OCV) ranges. To overcome this limitation, an adaptive recursive square root algorithm is used to online identify OCV and other battery model parameters. Then, the parameters of the extended Kalman filter are adaptively updated in different OCV ranges, which are distinguished based on the identified OCV. Additional filtering methods are employed to enhance the stability of the estimation. Large-scale experiments are conducted at different temperatures with various driving profiles for method validation. While conventional methods fail to converge, the proposed method ensures both high accuracy and stability, with a maximum absolute error of <2%. The viability of the proposed method is further verified using data collected from real battery systems. Our work lays a foundation for the reliable management of LiFePO 4 batteries in electric vehicles. • A novel state-of-charge estimation method for LiFePO 4 batteries is proposed. • State updating strategies are different in various open-circuit voltage ranges. • A series of methods are proposed to improve the robustness of the SOC estimation. [ABSTRACT FROM AUTHOR]

Herein, a series of pyrazoline based non-fullerene compounds (THP1-THP8) having ladder-like backbone was designed by structural modulation with various electron accepting moieties. The density functional theory (DFT) and time-dependent functional theory (TD-DFT) study was executed at M06/6-311G(d,p) level for structural optimization and to determine the electronic and optical characteristics of the pyrazoline based chromophores. The optimized structures were employed to execute frontier molecular orbital (FMO), transition density matrix (TDM), density of state (DOS), open circuit voltage (V oc) and reorganization energy analyses at the aforementioned level of DFT to comprehend the photovoltaic (PV) response of THP1-THP8. The red-shifted absorption spectrum (512.861–584.555 nm) with reduced band gap (2.507–2.881 eV) allow considerable charge transferal from HOMO to LUMO in all the studied compounds. Global reactivity parameters (GRPs) demonstrated high softness with considerable reactivity in THP1-THP8. Moreover, remarkable V oc values (2.083–2.973 V) were noted for all the derivatives (THP1-THP8). However, THP2 with lowest energy gap (2.364 eV), highest λ max (617.482 nm) and softness (0.423 eV) values is considered good candidate among afore-said chromophores. Hence, the studied chromophores with efficient properties are appropriate for experimentalists in terms of manufacturing of efficient OSCs. [ABSTRACT FROM AUTHOR]

Abstract The low open circuit voltage (V oc) of Cu 2 ZnSn(S,Se) 4 (CZTSSe) thin film solar cells limits their efficiency. CZTSSe absorbers were fabricated by sputtering Cu 2 ZnSnS 4 (CZTS) target and subsequent selenization treatment and then incorporated into solar cells. The influence of selenization temperature on the growth of the CZTSSe grains and device performance was examined. The absorber films were composed of a CZTSSe phase with high Se/(Se+S) ratios. As the selenization temperature was increased from 460 °C to 500 °C, the grains grew from the top to the bottom of the CZTSSe absorbers, and the average V oc of the CZTSSe solar cells increased from 284 mV to 371 mV. The band gaps (E g), derived from external quantum efficiency (EQE) data, were approximately 1.11 eV. Activation energies (E a) was extracted from temperature-dependent current density-voltage (J-V) measurements and used to evaluate the interface recombination level. The E a increased from 0.82 eV to 0.89 eV as the selenization temperature was increased, which approached the E g of CZTSSe. This was likely caused by reduced interface recombination because the grain boundaries decreased as the grains grew larger. An approximately linear relationship between the grain size and V oc was observed. The increase of grain size was achieved by optimizing the selenization temperature, which reduced interface recombination and resulted in an increased V oc. CZTSSe solar cells were fabricated with a maximum efficiency of 8.97%. Highlights • The grains grow from the top to the bottom of CZTSSe absorbers during selenization. • A positive correlation between open circuit voltage and grain size is observed and studied. • The highest efficiency of CZTSSe solar cell is 8.97%. [ABSTRACT FROM AUTHOR]

Highlights • An evaluation method of the interfacial resistance of a TEG device is proposed. • Analytic expressions for the V OC and I SC have been derived. • The electrical contact resistance of a thermoelectric device calculated. • The evaluation method can be used as an index to improve the soldering process. Abstract Research on the methodology for predicting and analyzing the performance of a thermoelectric device (TED) can offer various possibilities for enhancing its energy conversion characteristics. In this work, the methodology to determine the electrical contact resistance and the interfacial thermal resistance of a TED was studied. Based on one-dimensional heat transfer equations of power generation mode that includes electrical contact resistance and interfacial thermal resistance, we derived explicit expressions for the open circuit voltage and the short circuit current as the limiting cases of the external electrical load. The measurements of the open circuit voltage and the short-circuit current of TED were carried out for various thermal interface materials (TIMs) between the TED and heat reservoirs under varying compressive forces. The electrical contact resistance and the interfacial thermal resistance of a TED were determined by matching the measured values of the open circuit voltage and the short circuit current of a TED to the results of the analytic model. The electrical contact resistivity of the TED tested was approximately 3 × 10−9 Ωm2, irrespective of the compressive force, the hot-side temperature, and the TIMs. The interfacial thermal resistance varied sensitively with the TIMs and decreased with the compressive forces. [ABSTRACT FROM AUTHOR]

Abstract It is very important to estimate the state of charge accurately and to achieve the on-line updating of the battery parameter for the battery management system of electric vehicles. This research aims to develop a novel parameter adaptive method with dead zone for estimation of state of charge and other parameters of lithium-batteries. The dead zone refers to the definition of an interval based on the error of the battery model terminal voltage and the measured terminal voltage. When the error is no longer in the interval, the battery parameters are not estimated. Otherwise, the battery parameters are estimated. This research can be summarized as follows. First, the proposed method is applied to estimate all battery parameters including battery capacity, battery impedance and open circuit voltage. Second, the use of dead zone solves the problem of poor robustness of parameter adaptive algorithm when the initial state error is large, and the problem of instability. Finally, the experimental results indicate that the proposed method can achieve estimation accuracy with an error of 1%. Moreover, compared with the method used the same sampling time for estimating battery state and parameters, the dead zone method reduces the computation. Highlights • A parameter adaptive method with dead zone is developed for battery system. • The proposed approach improves the robustness and accuracy of SOC estimation. • The proposed approach reduces the computation for parameter adaptive method. • The proposed approach is validated under dynamic and constant current cycles. [ABSTRACT FROM AUTHOR]