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Tin-lead alloyed perovskite nanocrystals (PNCs) offer a promising pathway toward low-toxicity and air-stable light-emitting devices. However, substantial energetic disorder has thus far hindered their lighting applications compared to pure lead-based PNCs. A fundamental understanding of this disorder and its impact on optical properties is crucial for overcoming this limitation. Here, using temperature-dependent static and transient absorption spectroscopy, we meticulously distinguish the contributions of static disorder (including defects, impurities, etc.) and dynamic disorder (carrier-phonon interactions). We reveal how these disorders shape band-tail structure and ultimately influence inter-band carrier recombination behaviors. Surprisingly, we find that static and dynamic disorder primarily control band-tail defect states and bandgap renormalization, respectively, which together modulate fast carrier trapping and slow band-band recombination rates. Furthermore, we link these disorders to the tin-induced symmetry-lowering distortions in tin-lead alloyed PNCs. These findings illuminate critical design principles for highly luminescent, low-toxicity tin-lead PNCs, accelerating their adoption in optoelectronic applications. [ABSTRACT FROM AUTHOR]

We report our theoretical study on the effect of CuO as a hole transport layer in copper indium gallium selenide solar cell. This solar cell device was optimized by varying the thickness and doping density in the copper indium gallium selenide absorber, the CuO hole transport layer, and the bandgap in the absorber layer, as well as maximizing the performance of the device. The results show that the CuO hole transport layer in the optimized copper indium gallium selenide solar cell improves its power conversion efficiency from 26.29% to 30.66% at 300 K for the absorber layer thickness of 0.4 µm. The external quantum efficiency is improved from 70% to 80% because of the suppressed electron–hole recombinations due to the presence of the CuO layer. The study has the potential to fabricate highly efficient thin-film copper indium gallium selenide solar cells with a low-cost and non-toxic CuO hole transport layer. [ABSTRACT FROM AUTHOR]

Significant open‐circuit voltage deficit (VOC‐def) is regarded as the primary obstacle to achieving efficient kesterite solar cells. By leveraging a synergistic approach that combines photoluminescence, admittance spectroscopy and cathodoluminescence techniques, the theoretical models of radiative recombination in Cu2ZnSnS4 kesterite are revisited, allowing for a comprehensive clarification of both radiative and nonradiative recombination loss effects of VOC‐def in the kesterite bulk and at interfaces. This quantitative analysis of VOC‐def reveals that Cu/Zn disorder remains a fundamental limitation for kesterite solar cells, comparable to deep‐level defects. Specifically, it is demonstrated that the asymmetric photoluminescence band commonly observed in Cu2ZnSnS4 consists of two competing components: tail‐impurity recombination (conduction band → CuZn) and quasi‐donor‐acceptor‐pair recombination (ZnCu → CuZn). These findings confirm that Cu/Zn antisite defects and related potential fluctuations reduce the effective bandgap. Furthermore, it is confirmed that band tails in kesterite are the result of electrostatic potential fluctuations and bandgap fluctuations. The amplitude of the electrostatic potential fluctuations is estimated to be ≈30 meV. Bandgap fluctuations in kesterite are experimentally distinguished from electrostatic potential fluctuations for the first time, which leads to a bandgap contraction of about 130 meV. These studies provide crucial theoretical support for the advancement of kesterite photovoltaic technology. [ABSTRACT FROM AUTHOR]

The carrier recombination behavior of GaN-based blue laser diodes (LDs) is studied and analyzed by experiments and simulation calculations before lasing, with a particular focus on the role of Auger recombination. It is found that Auger recombination plays a crucial role in the decrease in differential efficiency and threshold current of GaN-based blue LDs. The theoretical calculation results show that a large Auger recombination rate may lead to a dominant recombination channel before lasing, which could exceed the radiation recombination and result in an obvious decrease in the differential efficiency. Such a high Auger recombination will dissipate a large number of carriers in the quantum well, resulting in deterioration of device performance, a higher threshold current and a lower efficiency. This work presents a method to evaluate Auger recombination through differential efficiency and also provides evidence that suppressing the Auger recombination rate is beneficial to improve the performance of blue LDs. [ABSTRACT FROM AUTHOR]

The electron transport layer (ETL)‐free perovskite solar cells (PSCs) have gained significant interest by simplifying the manufacture process and reducing the time/energy required for the fabrication of ETLs. Unfortunately, the performance of these ETL‐free PSCs still lags behind those of the conventional counterparts due to the slow electron extraction and undesired interfacial charge recombination loss at the buried interface. In this work, a facile and multifunctional biocolina thin layer is incorporated on the bottom electrodes to regulate the interface energy level alignment by forming an interface dipole layer, resulting in a suppressed nonradiative recombination and an improved charge extraction. Furthermore, the biocolina thin layer possess the capability to passivate the surface defects within the perovskite films while simultaneously facilitate the formation of perovskite crystals. Consequently, a remarkable enhancement in photovoltaic performance is observed in the biocolina‐based ETL‐free PSCs with an increase from 15.96 % to an outstanding 20.01 %. Additionally, the biocolina extends the stability and relieves the hysteresis effect through the interface defect passivation and inhibition of interface charge accumulation. This research contributes to the development of cost‐effective, simplified designs for highly efficient ETL‐free PSCs by modifying the bottom electrodes. [ABSTRACT FROM AUTHOR]

High‐quality perovskite (PVK) films is essential for the fabrication of efficient and stable perovskite solar cells (PSCs). However, unstable colloidal particles in PVK suspensions often hinder the formation of crystalline films with low defect densities. Herein, ethylenediaminetetraacetic acid (EDTA) as a colloidal stabilizer into lead iodide (PbI2) is introduced colloidal solutions. EDTA forms chelated complexes with Pb2+, enhancing the electrostatic repulsion and steric hindrance between colloidal particles. This stabilizes the particles and inhibits disordered motion (Brownian motion) and excessive aggregation. As a result, PbI2 films with a uniform hole distribution are formed, providing ample pathways for subsequent PVK film growth and sufficient space. During the film formation process, the replacement of molecules by formamidinium iodide (FAI) and EDTA slows down crystallization, ultimately leading to PVK films with large grain sizes and low defect density. By using this approach, champion power conversion efficiencies (PCEs) of 24.05% for FA0.97Cs0.03PbI3 PSC, 11.08% for CsPbBr3 PSC, and 25.19% for FA0.945MA0.025Cs0.03Pb(I0.975Br0.025)3 PSC are achieved. Moreover, the EDTA‐based FA0.97Cs0.03PbI3 device retains over 90% of its initial PCE after 1000 h at the maximum power point (MPP) under continuous illumination. [ABSTRACT FROM AUTHOR]

In photocatalytic water splitting and CO2 reduction, recently, cerium oxide (CeO2) has been widely investigated. Defects that can directly dominate carrier recombination are essential for the photocatalytic performance of CeO2. In this study, several photoluminescence (PL) peaks are observed on the (100) face of an undoped CeO2 single crystal, indicating the presence of defects. Moreover, we characterize carrier recombination using time-resolved photoluminescence (TR-PL) and microwave photoconductivity decay (μ -PCD) measurements. The temperature dependence of decay curves is the result of carrier trapping and emission at deep levels. These decay curves are observed separately using a 565 nm band-pass filter (BPF) based on the PL spectra. The trap energy level ( E T ) and majority carrier capture cross-section ( σ T ) of each defect are also analyzed using rate equations to fit the experimental results. The temperature-dependent time constants are well reproduced by a recombination model using hole traps HTinfrared and HTvisible at E T of 0.76 and 0.55 eV from the conduction or valence band, with estimated σ T of the order of 10−21 and 10−22 cm2 for without and with the BPF, respectively. These findings regarding the presence of multiple defects in a single crystal indicate the necessity to focus on defect control. [ABSTRACT FROM AUTHOR]

Despite the significant progress of blue perovskite light‐emitting diodes (PeLEDs) in recent years, huge challenges still remain in improving their efficiency and spectral stability. In this work, a new strategy is reported to realize efficient and spectral stable blue PeLEDs through synchronously optimizing light outcoupling and carrier recombination of perovskite films. By introducing additives in both precursor solution and antisolvent, the crystallization of the perovskite films is regulated, leading to a spontaneous formation of undulant morphology, which favorably enhances the light outcoupling efficiency. Meanwhile, the formation of low‐dimensional perovskite phases is suppressed, in accompany with a reduced defect density and accelerated energy transfer, leading to a rapid concentration of excitons in the target perovskite phases and a significant enhancement of radiative carrier recombination. Resultantly, the optimized blue perovskite films show a high photoluminescent quantum yield approaching 80%, and the corresponding optimized PeLEDs show a high external quantum efficiency (EQE) of 11.88%, which significantly outperforms the control device with only 1.96%. Importantly, the optimized perovskite films and PeLEDs also exhibit improved spectral stability. This work provides a new pathway toward realizing efficient and spectral‐stable PeLEDs via simultaneously tackling the issues of light outcoupling and carrier recombination in the devices. [ABSTRACT FROM AUTHOR]

The wider color gamut represents the better reproducibility of the real natural colors. Perovskite materials exhibit promising potential in full-color wide-gamut displays because of the wide tunability and high saturability of their photon emission. However, the full-color wide gamut (>100% Rec.2020) has not been constructed due to the lack of the extreme red primary color (∼700 nm). Herein, the widest color gamut is realized, wherein α-CsPbI3 is used to generate the extreme red primary color. An in-situ encapsulation approach is advised to stabilize α-CsPbI3 at room temperature by means of polyvinylpyrrolidone (PVP). The α-CsPbI3 encapsulated by PVP (denoted as P-CPI) shows highly saturated (FWHM (full width at half maximum) ∼28 nm) and extremely (∼697 nm) red emission. The green emission is provided by P-CPBr (CsPbBr3 with PVP) which is also synthesized using the universal in-situ encapsulation approach. With the assistance of a commercial GaN chip, the RGB gamut is extended to the widest (151% NTSC, 113% Rec.2020). [ABSTRACT FROM AUTHOR]

Quantum‐dot light‐emitting diodes (QD‐LEDs) have gained significant attention for next‐generation display and lighting systems owing to their superior color selectivity and color purity. To maximize the efficiency of QD‐LED devices, it is of great importance to identify the key factors that govern their electro–optical properties. The efficiency of QD‐LED devices is strongly influenced by combinatorial processes, represented by the Shockley‐Read‐Hall rate A, Langevin strength B, and Auger probability C (ABC parameters) of quantum‐dots (QDs), along with photon extraction efficiency of QD‐LED devices. In this study, an integrated computational framework is proposed to accurately analyze the electro–optical properties of QD‐LED devices. The experimental device properties are characterized by ABC and photon extraction efficiency parameters through an innovative numerical data‐fitting procedure. Utilizing these parameters, a parametric analysis is performed based on a complete computational charge transport simulation model to explore the influence of the combinatorial exciton recombination processes. This computational framework aligns excellently with experimental results, showcasing its remarkable reliability and effectiveness in both quantitatively characterizing QD nanoparticles and in the detailed analysis of the electro–optical properties of QD‐LED devices. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have undergone an unprecedentedly rapid development in both power conversion efficiency (PCE) and operational durability. However, a number of unknown challenges remain before PSC products are ready to launch. Herein, it is demonstrated that the vacuum deposition of gold (Au) onto the organic hole‐transport layer (HTL) results in Au penetration into the perovskite layer. This Au penetration proves to be a limiting factor in PCE due to detrimental carrier recombination caused by the penetrated Au component inside the perovskite light absorber. To mitigate this issue, a thin molybdenum oxide (MoOx) interlayer between the organic HTL and the Au electrode is introduced, effectively reducing the Au penetration and suppressing the carrier recombination. Consequently, this MoOx introduction increases PCEs from ≈16.9% to ≈19.6% by ≈2.7%. Furthermore, using the MoOx interlayer improves the long‐term durability of PSCs. These findings are crucial in elucidating a basic mechanism that limits PCE and in advancing the fabrication of PSC products with even higher performance. [ABSTRACT FROM AUTHOR]

Use and performance criteria of photonic devices increase in various application areas such as information and communication, lighting, and photovoltaics. In many current and future photonic devices, surfaces of a semiconductor crystal are a weak part causing significant photo-electric losses and malfunctions in applications. These surface challenges, many of which arise from material defects at semiconductor surfaces, include signal attenuation in waveguides, light absorption in light emitting diodes, non-radiative recombination of carriers in solar cells, leakage (dark) current of photodiodes, and light reflection at solar cell interfaces for instance. To reduce harmful surface effects, the optical and electrical passivation of devices has been developed for several decades, especially with the methods of semiconductor technology. Because atomic scale control and knowledge of surface-related phenomena have become relevant to increase the performance of different devices, it might be useful to enhance the bridging of surface physics to photonics. Toward that target, we review some evolving research subjects with open questions and possible solutions, which hopefully provide example connecting points between photonic device passivation and surface physics. One question is related to the properties of the wet chemically cleaned semiconductor surfaces which are typically utilized in device manufacturing processes, but which appear to be different from crystalline surfaces studied in ultrahigh vacuum by physicists. In devices, a defective semiconductor surface often lies at an embedded interface formed by a thin metal or insulator film grown on the semiconductor crystal, which makes the measurements of its atomic and electronic structures difficult. To understand these interface properties, it is essential to combine quantum mechanical simulation methods. This review also covers metal-semiconductor interfaces which are included in most photonic devices to transmit electric carriers to the semiconductor structure. Low-resistive and passivated contacts with an ultrathin tunneling barrier are an emergent solution to control electrical losses in photonic devices. [ABSTRACT FROM AUTHOR]

In this work, an n-i-p perovskite solar cell structure comprising a lead-free methyl ammonium iodide (CH3NH3SnI3) as an absorber layer and Cuprous Tricynate (CuSCN) as a hole transport material is numerically modeled and simulated using SCAPS-1D software. Influence of various material parameters such as doping concentration of the absorber layer, thickness of the different layers, effect of different back contacts, defects in the absorber layer etc., is studied as a function of cell parameters, i.e., fill factor (FF), the open circuit voltage (Voc), the short circuit current density (Jsc), and the power conversion efficiency (PCE) to explore the photovoltaic performance of the designed solar cell structure. Upon optimization of the different material parameters, the modelled solar cell has resulted in enhanced photovoltaic performance with Voc ~ 1.08 V, Jsc = 33.78 mA/cm2, FF = 87.42% and PCE = 32.00%. [ABSTRACT FROM AUTHOR]

To develop semiconductor detectors based on TlBr with excellent energy resolution at high yields, a variety of characterization methods for TlBr crystals are necessary. Among the various methods based on excitation by photons or ionizing radiation, we chose transient absorption measurements after the irradiation of pulsed electron beams to analyze the recombination dynamics of electron-hole pairs generated by the electron beams. The decay behavior of the transient absorption depended on the pulse intensity and was satisfactorily fitted with a decay function based on bimolecular recombination dynamics. The bimolecular recombination coefficients obtained from the fitting were similar for the samples cut from different parts of a crystal boule. Assuming that the recombination occurred through Shockley-Read-Hall bimolecular recombination via electronic levels of defects within the bandgap, the result indicates that the concentrations of the defects responsible for the recombination were similar for the samples out from different parts of the crystal boule. [ABSTRACT FROM AUTHOR]

One of the key issues impeding the enhancement of power conversion efficiency (PCE) of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells is the severe carrier recombination at CZTSSe/MoSe2 back interface, primarily arising from the reverse electric field formed between CZTSSe and n-type MoSe2 produced after selenization. To inhibit recombination at back interface, herein, the MoSe2 layer is converted from n-type to p-type by V doping in site through reaction of V-alloyed Mo (Mo:V) back electrode with Se during selenization, and CZTSSe solar cells with pþ-type V-doped MoSe2 (MoSe2:V) interface layer are fabricated. It is found that the PCE of the device rises from 8.34% to 9.63% as back contact changes from soda lime glass (SLG)/Mo/n-MoSe2 to SLG/Mo:V/pþ-MoSe2:V. The quantitative analysis demonstrates that the increased PCE predominantly originated from the decreased reverse saturated current density (J0), followed by the decreased series resistance (RS), and lastly by the increased photogenerated current density (JL). The influence mechanism of the SLG/Mo:V/MoSe2:V back contact on device performance is suggested by studying the properties of Mo:V and MoSe2:V films and CZTSSe/MoSe2:V heterojunction. This work emphasizes the vital significance of the back surface passivation field induced by pþ-MoSe2:V/p-CZTSSe heterojunction, which is enlightening for optimizing the back contact in kesterite photovoltaics. [ABSTRACT FROM AUTHOR]

We prepared ternary organic solar cells (OSCs) by incorporating the medium wavelength absorption polymer PSEHTT into the PM6:L8-BO binary system. The power conversion efficiency (PCE) is improved from 15.83% to 16.66%. Although the fill factor (FF) is slightly reduced, the short-circuit current density (JSC) and open-circuit voltage (VOC) are significantly increased at the same time. A small amount of PSEHTT has a broad absorption spectrum in the short wavelength region and has good compatibility with PM6, which is conducive to fine-tuning the photon collection and improving the JSC. In addition, the highest occupied molecular orbital (HOMO) energy level of PSEHTT is deeper than that of PM6, which broadens the optical bandgap. This study provides an effective method to fabricate high-performance ternary OSCs by using a lower concentration of PSEHTT with PM6 as a hybrid donor material, which ensures a better surface and bulk morphology, improves photon collection, and broadens the optical bandgap. [ABSTRACT FROM AUTHOR]

Inorganic semiconductors like silicon and germanium are the foundation of modern electronic devices. However, they have certain limitations, such as high production costs, limited flexibility, and heavy weight. Additionally, the depletion of natural resources required for inorganic semiconductor production raises concerns about sustainability. Therefore, the exploration and development of organic semiconductors offer a promising solution to overcome these challenges and pave the way for a new era of electronics. New applications for electronic and optoelectronic devices have been made possible by the recent emergence of organic semiconductors. Numerous innovative results on the performance of charge transport have been discovered with the growth of organic electronics. These discoveries have opened up new possibilities for the development of organic electronic devices, such as organic solar cells, organic light-emitting diodes, and organic field-effect transistors. The use of organic materials in these devices has the potential to revolutionise the electronics industry by providing low-cost, flexible, and lightweight alternatives to traditional inorganic materials. The understanding of charge carrier transport in organic semiconductors is crucial for the development of efficient organic electronic devices. This review offers a thorough overview of the charge carrier transport phenomenon in semiconductors with a focus on the underlying physical mechanisms and how it affects device performance. Additionally, the processes of carrier generation and recombination are given special attention. Furthermore, this review provides valuable insights into the fundamental principles that govern the behaviour of charge carriers in these materials, which can inform the design and optimisation of future devices. [ABSTRACT FROM AUTHOR]

As compared to the predecessor Cu(In,Ga)Se2 device, the current efficiency of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells is still much lower mainly due to the known carriers recombination issue within interface and absorber bulk. In contrast to the majority of researches concerning recombination issues that focus on either single absorber bulk or interface passivation strategy, this study is pioneering in constructing synergistic passivation effects (SPE) to address the bulk and interface recombination issue simultaneously. By introducing a novel niobium pentoxide passivation layer into the back electrode interface (BEI), it is identified that SPE can be constructed due to Nb (& O) diffusion from Nb2O5 layer to absorber bulk and BEI during high‐temperature selenization. The chemical passivation effect is fulfilled via the intrinsic high resistance characteristic of Nb2O5 layer, and also through the NbOx passivation aiming to absorber bulk benefited from Nb (& O) diffusion. Meanwhile, the occupations of Nb (& O) on the Mo (& Se) sites induce a conduction type inversion in MoSe2 interfacial layer and create a preferable interface p+‐Mo(Se,O)2:Nb/CZTSSe, achieving an interfacial field passivation effect. Ultimately, the promoted absorber quality and improved charge carrier transportation from SPE contribute to the boost of device performance beyond 10% efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] Understanding the carrier recombination processes in Sb 2 Se 3 is essential for its optoelectronic applications. In this work, carrier recombination dynamics in Sb 2 Se 3 were studied by broad band transient absorption spectroscopy. Firstly, the contribution of photothermal effect to the transient absorption spectrum was thoroughly discussed. It is confirmed that the excited state absorption (ESA) band with lifetime of several nanoseconds results from co-contribution of photo thermal effect and deep trapped carrier absorption. Secondly, the features of transient absorption spectrum on picosecond time scale were interpreted. The short-lived ESA band around 1000 nm was assigned to shallow trapped carrier absorption, while not band gap renormalization (BGR) or free carrier absorption. By globally fitting the transient absorption spectrum, the hot carrier cooling time and time constant for free carrier relax into deep trap state were determined to be 0.25∼0.45 ps and 3.1∼8.7 ps, respectively. Finally, we built up the carrier recombination model of Sb 2 Se 3. The experimental results in this work will improve the understanding on the carrier recombination in Sb 2 Se 3. [ABSTRACT FROM AUTHOR]

The PCE of CZTSSe solar cells doped with non-uniform Cd doped in the middle of the absorber layer increased from 8.88% to 10.89%. The "V"-shaped gradient band gap structure in the absorption layer provides a favorable back electric field and reduces the carrier recombination at the Mo/CZTSSe interface for the collection of photogenerated carriers. In addition, the optimal position of non-uniform Cd doped absorber film is simulated theoretically and investigated experimentally. It is worth noting that when studying the stability of the cell PCE, we found that the efficiency of the non-uniform Cd-doped cell was further improved from 10.28% to 10.94% after being exposed to air for 30 days. Compared with undoped cells, Cd-doped cells decay significantly slower and show better stability. [Display omitted] • "V"-shaped gradient band gap prepared via Cd doped in the middle of the absorber layer of CZTSSe. • The "V"-shaped gradient band gap structure in the absorption layer provides a favorable back electric field. • Cell performance of non-uniform Cd doping is superior to that of uniform Cd doping. • The optimal position of non-uniform Cd doped absorber film is simulated theoretically and investigated experimentally. • Cd doping can enhance the stability of the CZTSSe solar cells. Severe carrier recombination at the back (Mo/CZTSSe) and front (CZTSSe/CdS) interfaces is one of the most important reasons hindering the development of open-circuit voltage (V OC) and fill factor (FF) in Cu 2 ZnSn(S, Se) 4 (CZTSSe) solar cells. In this study, we intentionally introduced a non-uniform distribution of Cd impurities into the middle of the absorber layer, designing and fabricating a CZTSSe solar cell with a non-uniform "V"-shaped graded bandgap structure. This structure is aimed at providing a favorable back electric field, reducing carrier recombination at the Mo/CZTSSe interface. The PCE of the CZTSSe solar cell improved from 8.88 % to 10.89 %, significantly enhancing FF and V OC. Additionally, we utilized the solar cell simulation software SCAPS-1D to simulate the position of the minimum point in the V-shaped graded bandgap and combined this with experimental results to explore the effect of Cd doping location on the performance of CZTSSe solar cells. It's worth noting that the non-uniform Cd-doped solar cell displayed exceptional stability, demonstrating an efficiency enhancement from 10.28 % to 10.94 % after being exposed to air for 30 days. [ABSTRACT FROM AUTHOR]

Potential barriers between the waveguide layer and MQW active region may influence injection efficiency significantly, which is important in improving output characteristics of GaN-based green laser diodes (LDs). In this study, potential barriers and injection efficiency of LDs are investigated by simulation methods. It is found that different indium content in quantum barrier layers results in different potential barrier heights, leading to different recombination rates in upper and lower waveguide layers, and the injection efficiency can be modulated effectively. An eclectic choice of indium content can suppress recombination in two waveguide layers, improving the output characteristics of green LDs. Additionally, a composite lower waveguide layer structure is proposed to reduce the negative effect of potential barriers. High output power and low threshold current are achieved owing to the reduction in electron injection blockage and hole leakage effects. [ABSTRACT FROM AUTHOR]

An amorphous boron nitride (aBN) layer is inserted between Cu2ZnSn(S,Se)4 (CZTSSe) films and Mo back electrode of CZTSSe solar cell by magnetron sputtering to mitigate the carrier recombination at back interface by tuning energy band alignment and suppressing formation of secondary phases and Mo(S,Se)2. The effect of the aBN layer on power conversion efficiency (PCE) of CZTSSe solar cell is investigated by numerical simulation and experiment. It is found that PCE is greatly improved via the insertion of suitable thick aBN layer, which is attributed to increased open‐circuit voltage (VOC) and fill factor (FF). By quantitative analysis, it is deduced that the increased VOC originates mainly from decrease in reverse saturation current density (J0), followed by increase in shunt resistance (RSh), and the increased FF is mainly due to the decreased J0, followed by increased RSh and decreased photogenerated current density (JL). By optimizing aBN thickness through tuning sputtering time, the PCE increases from 8.68% of CZTSSe solar cell without the aBN layer to 9.51% of the CZTSSe solar cell with aBN layer. The influence mechanism of the aBN layer on the PCE is suggested by analyzing quantitatively the effect of the aBN layer on JL and electrical parameters. [ABSTRACT FROM AUTHOR]

For engineers and physicists, it is important to investigate the excitement of thermoelastic vibrations by photothermal effects since they are used in many fields. For this purpose, the photo-thermoelastic waves throughout the photothermal process for a semiconducting half-space have been investigated in this work. In contrast to many scientists who ignore the coupling effects between plasma and thermoelasticity, the influences of thermoelastic, carrier recombination and electronic elastic deformations on the semiconductor solids have been studied here. One of the thermoelastic theories which is appropriate for the limited speeds of heat waves has been considered. To solve the non-dimensional system resulting from generalized thermal elasticity theory without dissipating energy, coupled plasma, elastic wave and thermal wave equations, the normal mode technique has been applied. The amplitude expression for the field variables have been derived and graphically displayed. The numerical results have been verified and the influence of various factors has been also studied. In addition, several special cases of interest have been deduced. The analysis showed that the effective parameters have important effects on the physical fields by applying the presented model. [ABSTRACT FROM AUTHOR]

In this paper, a high‐efficiency silicon‐based thin‐film solar cell is proposed based on double‐layer nano‐pyramid (DNP) arrays. In the model, the surface and bottom of the silicon photovoltaic layer are embedded with silicon nano‐pyramid array and aluminum nano‐pyramid array, respectively. The optical and electrical parameters of the DNP solar cell are presented by using the 3D finite‐difference time‐domain (FDTD) method. The short‐circuit current density (Jsc), integrated absorption (α) and photoelectric conversion efficiency (η) of the optimized DNP solar cell are 43.61 mA cm−2, 95.20% and 27.12%, respectively. Compared with the planar solar cell, the α and η of the DNP solar cell are increased by 45.31% and 15.77%, respectively. To investigate the performance of the proposed solar cell, the principle of light absorption enhancement is analyzed by spectrum and field strength distributions for the DNP structure. Furthermore, the carrier recombination and manufacturing of the DNP solar cell, and compared the structures of different arrays is studied. Further results show that the DNP structure has excellent light absorption and tolerance, which has positive significance for the development of silicon‐based thin‐film solar cells. [ABSTRACT FROM AUTHOR]

Additives play a critical role for efficient perovskite light‐emitting diodes (PeLEDs). Here, we report a novel phosphonate/phosphine oxide dyad molecular additive (PE‐TPPO), with unique dual roles of passivating defects and enhancing carrier radiative recombination, to boost the device efficiency of metal–halide perovskites. In addition to the defect passivation effect of the phosphine oxide group to enhance the photoluminescence intensity and homogeneity of perovskite film, the phosphonate group with strong electron affinity can capture the injected electrons to increase local carrier concentration and accelerate the carrier radiative recombination in the electroluminescence process. Owing to their synergistic enhancement on device efficiency, quasi‐two‐dimensional green PeLEDs modified by this dyad additive exhibit a maximum external quantum efficiency, current efficiency, and power efficiency of 25.1 %, 100.5 cd A−1, and 98.7 lm W−1, respectively, which are among the reported state‐of‐the‐art efficiencies. [ABSTRACT FROM AUTHOR]

The optical properties of InGaN/GaN violet light-emitting multiple quantum wells with different thicknesses of GaN quantum barriers are investigated experimentally. When the barrier thickness decreases from 20 to 10 nm, the photoluminescence intensity at room temperature increases, which can be attributed to the reduced polarization field in the thin-barrier sample. However, with a further reduction in the thickness to 5 nm, the sample's luminescence intensity decreases significantly. It is found that the strong nonradiative loss process induced by the deteriorated crystal quality and the quantum-tunneling-assisted leakage of carriers may jointly contribute to the enhanced nonradiative loss of photogenerated electrons and holes, leading to a significant reduction in photoluminescence intensity of the sample with nanoscale ultrathin GaN quantum barriers. [ABSTRACT FROM AUTHOR]

Carbon-based CsPbI 3 perovskite solar cells without hole transporter (C-PSCs) have achieved intense attention due to its simple device structure and high chemical stability. However, the severe interface energy loss at the CsPbI 3 /carbon interface, attributed to the lower hole selectivity for inefficient charge separation, greatly limits device performance. Hence, dipole electric field (DEF) is deployed at the above interface to address the above issue by using a pole molecule, 4-trifluoromethyl-Phenylammonium iodide (CF 3 -PAI), in which the ─NH 3 group anchors on the perovskite surface and the ─CF 3 group extends away from it and connects with carbon electrode. The DEF is proven to align with the built-in electric field, that is pointing toward carbon electrode, which well enhances hole selectivity and charge separation at the interface. Besides, CF 3 -PAI molecules also serve as defect passivator for reducing trap state density, which further suppresses defect-induced non-radiative recombination. Consequently, the CsPbI 3 C-PSCs achieve an excellent efficiency of 18.33% with a high V OC of 1.144 V for inorganic C-PSCs without hole transporter., (© 2024 Wiley‐VCH GmbH.)

This article describes a superior passivation of p-type (p+) Si surface by an Al2O3 thin film that is synthesized by plasma-assisted atomic layer deposition (ALD) for ultraviolet-sensitive silicon photomultipliers (SiPMs), compared to conventional SiO2 and SiNx passivation schemes. The superiority of Al2O3 passivation is due not only to a sufficiently low interface defect density, but also to a high density of built-in negative charges. A 7-nm thin Al2O3 film can yield an emitter saturation current density of ~8 fA/cm2 on a high sheet resistance p+ layer, compared to ~60 and ~1480 fA/cm2 for thermal SiO2 and SiNx passivation. This superior surface passivation allows the photon-generated carriers to have higher probabilities to reach the high-field region to trigger an avalanche event. In addition, the Al2O3 thin film provides very low values of effective surface recombination velocity on low resistivity n- and p-type Si surfaces, which can lead to well-passivated surface features on the guard ring and trench isolation regions of SiPM. These demonstrate the potential of the Al2O3 thin film passivation to improve the quantum efficiency and thus photo-detection efficiency (PDE) of ultraviolet-sensitive SiPM with p+/n−/n/n+ structure. [ABSTRACT FROM AUTHOR]

Silver antimony sulfide (AgSbS2) is considered a promising photovoltaic absorber material because of its suitable bandgap, large absorption coefficient, and environmental friendliness. However, the photovoltaic performance of AgSbS2‐based solar cells is far from expectation and the applications of AgSbS2 are limited by the underdeveloped fabrication technology. Herein, an effective method is developed to improve the photovoltaic performance of devices by adding indium (In) into the Ag–Sb–S system followed by a selenization process. With the addition of In, the morphology uniformity and the crystallinity of the films are simultaneously improved due to the diminished defects such as pinholes and cracks, leading to a better heterojunction interface between Ag1−xIn2xSb1−xSySe2−y and CdS. The Hall effect measurements demonstrate that the carrier concentration of the films effectively increases to 8.16 × 1014 cm−3 on adding In. The optical characterization suggests that In addition significantly enhances the optical absorption and broadens the absorption wavelength range. Furthermore, the conduction band offset between the absorber and the buffer layer is substantially reduced by adding In, which lessens the carrier recombination at the interface, increasing the carriers transport efficiency. The power conversion efficiency of the Ag1−xIn2xSb1−xSySe2−y device is largely improved from 0.74% (In/Sb = 0) to 1.98% (In/Sb = 0.47). [ABSTRACT FROM AUTHOR]

• Zn(O,S) is proposed as a buffer layer in Sb 2 (S,Se) 3 solar cells. • Efficiency of Sb 2 (S,Se) 3 /Zn(O,S) cells improved by optimization of sulfur content. • Optimized sulfur content [S/(O + S)] in the ZnO 1−y S y ranging 50–60%. • Optimized selenium content [Se/(S + Se)] in the Sb 2 (S 1−x Se x) 3 ranging 80–90%. • Efficiency of Sb 2 Se 3 solar cells improved from 9.2% to 15.65%. The purpose of this study is the efficiency improvement of the Sb 2 Se 3 solar cells. In this study, an experimental Sb 2 Se 3 solar cell (glass/Mo/MoSe 2 /Sb 2 Se 3 /CdS/ZnO/ZnO:Al/Ag) with an efficiency record of 9.2% has been simulated. Absorber/buffer interface engineering plays a significant role in enhancing the efficiency of Sb 2 Se 3 solar cells. To achieve this purpose, two approaches have been considered: first, adding sulfur to Sb 2 Se 3 absorber, and second, using an alternative buffer with a wider bandgap instead of conventional CdS buffer. The effects of various x = Se/(S + Se) ratios of Sb 2 (S 1−x Se x) 3 absorber layer on the photovoltaic performance were investigated. For Sb 2 (S,Se) 3 /CdS solar cell, optimum Se/(S + Se) mole fraction of 0.6 < x < 0.8 leads to improved efficiency. Also, ZnO 1−y S y buffer layer was applied to replace the conventional CdS buffer layer of Sb 2 Se 3 solar cells to reduce parasitic absorption and improve the short-circuit current density (J sc). Bandgap for ZnO 1−y S y semiconductor is higher than CdS. So, this leads to improved external quantum efficiency at short wavelengths. Optimization of band alignment through ZnO 1−y S y buffer layer reduces interface carrier recombination and improves open-circuit voltage (V oc). The band alignment at the Sb 2 (S 1−x Se x) 3 /ZnO 1−y S y interface is optimized by adjusting the selenium-to-sulfur ratio in the absorber layer and sulfur-to-oxygen ratio in the buffer layer. This work reveals that the most suitable interface for Sb 2 (S 1−x Se x) 3 /ZnO 1−y S y heterojunction is formed when sulfur mole fractions ranging 0.5–0.6 in the Zn(O,S) buffer layer and 0.1–0.2 in the Sb 2 (S,Se) 3 absorber layer. The results show that the efficiency improves from 9.2% to 15.65%, which represents a 70% improvement compared with the conventional Sb 2 Se 3 /CdS solar cell. [ABSTRACT FROM AUTHOR]

This study investigated the laser‐induced damage arising from 266 and 532 nm laser ablation of SiNx films on alkaline textured Si surfaces with nanosecond and picosecond pulse durations using a combination of optical‐thermal simulations and measurements of carrier recombination current density. Simulations predict that the melting depth is limited to within 150 nm of the SiNx/Si surface after 266 nm ps laser irradiation due to the greater absorption in both the SiNx and Si resulting in more direct ablation, while temperatures exceeding the melting temperature of Si are predicted to extend up to 1000 nm into the Si substrate with 532 nm ps pulses leading primarily to spallation. Ablation of the SiNx by 266 nm ps irradiation is predicted to be more homogeneous on smaller sized pyramids due to the increased absorption of double‐bounce reflected light on the pyramid faces. This finding has implications for applications requiring uniform ablation of dielectrics on textured Si surfaces. Ablation of SiNx by the longer wavelength 532 nm ps pulses also increases carrier recombination compared to that incurred with 266 nm ps pulses due to the increased melting depth. Longer ns pulses result in less steep temperature gradients and, for 266 nm pulses, an increased melting depth compared to ps pulses. Consequently, shorter ps UV pulses are preferred for SiNx ablation on Si surfaces due to their reduced laser damage penetration, whereas the less steep temperature gradients resulting from ns 532 nm pulses are beneficial for laser doping to form selective emitters. [ABSTRACT FROM AUTHOR]

Minimising charge losses at silicon interfaces is a major development area for highly efficient solar cells. Here we report on the interface improvements achieved by establishing a surface electric field during low-temperature firing of dielectric thin films. By inducing a corona electric field on the surface of a thin film stack, we observe significant modifications to the silicon-dielectric interface upon annealing, which correlate with the characteristics of interface defects. The passivation properties of the interfaces strongly depend on the polarity and strength of the electric field during firing, as well as the dielectric materials in the layer stack. We show that the surface electric fields not only influence surface carrier population but also affect the resulting chemical interface properties post-annealing. It is postulated that hydrogen migration plays a role in these observed effects. Leveraging the corona-induced electric field enables fine-tuning of both the chemical and field-effect passivation in thin film surface dielectrics, resulting in recombination current densities as low as 2.8 fA cm−2 in research-grade float zone silicon, and 14 fA cm−2 in industrial-grade textured silicon. The simplicity and versatility of the thin film electric polarisation enable a new strategy for controlling and exploiting the chemical enhancement of interfaces in solar cell devices, from current TOPCon and PERC devices to future multijunction silicon-based cells. • Hydrogen passivation from dielectrics is central to improving silicon solar cell performance. • Charge-assisted field effect passivation not only controls carrier population, but also affects interface chemistry. • Chemical passivation of Si-SiO 2 -SiN x interfaces depends on the polarity and strength of the surface electric field. • Optimal processing requires control of surface electric fields, chemical interface, hydrogenation and charge migration. • Understanding the interplay of hydrogen and electric fields is crucial for optimising silicon solar cell performance. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) stand at the forefront of photovoltaic research, with current efficiencies surpassing 26.1%. This review critically examines the role of electron transport materials (ETMs) in enhancing the performance and longevity of PSCs. It presents an integrated overview of recent advancements in ETMs, like TiO 2 , ZnO, SnO 2 , fullerenes, non-fullerene polymers, and small molecules. Critical challenges are regulated grain structure, defect passivation techniques, energy level alignment, and interfacial engineering. Furthermore, the review highlights innovative materials that promise to redefine charge transport in PSCs. A detailed comparison of state-of-the-art ETMs elucidates their effectiveness in different perovskite systems. This review endeavors to inform the strategic enhancement and development of n-type electron transport layers (ETLs), delineating a pathway toward the realization of PSCs with superior efficiency and stability for potential commercial deployment., (© 2024 Wiley‐VCH GmbH.)

In recent years, the investigation of the complex interplay between the nanostructure and photo-transport mechanisms has become of crucial importance for the development of many emerging photovoltaic technologies. In this context, Kelvin probe force microscopy under frequency-modulated excitation has emerged as a useful technique for probing photo-carrier dynamics and gaining access to carrier lifetime at the nanoscale in a wide range of photovoltaic materials. However, some aspects about the data interpretation of techniques based on this approach are still the subject of debate, for example, the plausible presence of capacitance artifacts. Special attention shall also be given to the mathematical model used in the data-fitting process as it constitutes a determining aspect in the calculation of time constants. Here, we propose and demonstrate an automatic numerical simulation routine that enables to predict the behavior of spectroscopy curves of the average surface photovoltage as a function of a frequency-modulated excitation source in photovoltaic materials, enabling to compare simulations and experimental results. We describe the general aspects of this simulation routine and we compare it against experimental results previously obtained using single-point Kelvin probe force microscopy under frequency-modulated excitation over a silicon nanocrystal solar cell, as well as against results obtained by intensity-modulated scanning Kelvin probe microscopy over a polymer/fullerene bulk heterojunction device. Moreover, we show how this simulation routine can complement experimental results as additional information about the photo-carrier dynamics of the sample can be gained via the numerical analysis.

The performance of inverted PSC devices based on the PTB7-Th:PC 71 BM photoactive layer system has been significantly improved by incorporating the MgO/ZnO stacked films with excellent dual-function interface characteristics. A highly efficient inverted polymer solar cell (PSC) has been successfully demonstrated by utilizing a wide bandgap magnesium oxide (MgO) film and ZnO stacked structure as an effective cathode interfacial layer. The MgO/ZnO bilayer structure is designed to combine the superiorities of both ZnO ETL and MgO film, based on the efficiency comparison of the PSCs without and with MgO interlayer. The ZnO film can serve as an efficient electron transport layer (ETL), while the MgO layer can reduce the surface defects of FTO and block the holes effectively, leading to an elevated electron collection and suppressed carrier recombination at the interface. With the excellent dual functions interface characteristics induced by the MgO/ZnO stacked films, the corresponding inverted PSC device based on the PTB7-Th:PC 71 BM photoactive layer system presents a superior power conversion efficiency (PCE) of 11.02%, which is higher than that of the PSC without MgO (8.79%). We believe that the MgO/ZnO bilayer structure is a superior interfacial contender for the organic photovoltaics and other photoelectric devices requiring cathode interfacial layers. [ABSTRACT FROM AUTHOR]

In this article, we investigated the destructive behavior of the latest power diode when operating a hard-switching process. From the numerical simulation analysis, the destruction behavior originates in the enhanced impact ionization at the p-n junction on the anode side and current filament in the active region. A relaxing electric field on the anode side and a moderated electric field on the cathode side prevent the above-mentioned behavior. These improvements result from controlling the carrier-plasma layer in the n-buffer layer on the cathode side. This article demonstrates the effective n-buffer technology for the power diode that achieves superior dynamic robustness and high operating temperature over 448 K. [ABSTRACT FROM AUTHOR]

The wide use of press-pack insulated-gate bipolar transistors (IGBTs) in high-voltage dc (HVdc) applications makes the accurate modeling of high-voltage press-pack IGBTs more urgent. Based on the mechanism of the switching transient, a physics-based electrothermal transient model of the high-voltage press-pack IGBT is proposed. Considering the wider base width of high-voltage IGBTs (HVIGBTs), a transient model of the HVIGBT with buffer layer is presented taking into account the carrier recombination in the base region and the injection level in the buffer layer. Besides, a modified thermal network of press-pack IGBTs is implemented considering the double-sided heat transfer structure. An electrothermal coupling model of high-voltage press-pack IGBTs is then obtained combining the proposed electro and thermal models. Finally, simulations of key dynamic performances of the proposed HVIGBT model match well with the testing results. Furthermore, the HVdc interruption process of a solid breaker with different number of series-connected IGBTs is simulated using the proposed IGBT model and tested. The testing results show good consistency between the simulated and measured voltage and current of the series-connected press-pack IGBTs, which brings strong support to the accurate design of solid breakers in the HVdc transmissions. [ABSTRACT FROM AUTHOR]

To analyze the dominant recombination, researchers often consider the diode ideality factor (nid), determined from the fitting of a semi‐log plot of light intensity–dependent open‐circuit voltage (Voc(lnI/I0)) to a linear dependence. This value is called "nid,Voc". Theoretically, nid is the exponential dependence factor in the recombination rate function of the split of quasi‐Fermi levels. This nid is called "nid,C". Herein, correlations between nid,Voc, nid,C, and the dominant recombination are reconsidered using a validated numerical drift–diffusion model and a diode current analysis in perovskite solar cell devices having accumulations of charged defects near the carrier transporting interfaces. It is found that the interplay between the recombination processes affects the linearity of the Voc(lnI/I0) plots. Devices having a single dominant recombination process exhibit Voc(lnI/I0) plots that appear to be linear, resulting in nid,Voc ≈ nid,C of the dominant recombination. Conversely, bends in the Voc(lnI/I0) curves indicate that different (multiple) recombination mechanisms dominate at different light intensities, so nid,Voc is an effective nid of the total diode current whose value is not consistent with any nid,C values. This work provides more understanding of nid and how to interpret a Voc(lnI/I0) curve more correctly for the insights into recombination mechanisms. [ABSTRACT FROM AUTHOR]