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Abstract: Background: Inflammation and inflammatory markers play an important role in acute ischemic stroke (AIS). In an earlier study, we discovered a 120-kDa protein that was highly expressed in healthy participants, but either was not expressed or was barely expressed in AIS patients. The purpose of the present work was to isolate, characterize, and evaluate this 120-kDa protein in blood samples of AIS patients. In addition, we investigated how the identified protein compared with protein S-100ßß, neuron-specific enolase (NSE), and cytokine interleukins IL-2 and IL-10. Methods: The 120-kDa protein band was analyzed via LC-MS/MS analysis. Then, the 120-kDa protein was evaluated using an enzyme-linked immunosorbant assay in serum samples from AIS patients, which were collected 0, 24, 48, 72 and 144 h after admission. Results: The amino acid sequence of an internal fragment identified the 120-kDa protein as inter-α-trypsin inhibitor heavy chain 4 (ITIH4). The ITIH4 protein was completely absent in AIS patients as compared to those in the control group, and serum levels returned to normal in AIS patients as their condition improved. Expression of S-100 ßß, NSE, IL-2, and IL-10 were highly correlated with ITIH4 expression. Conclusions: ITIH4 is an anti-inflammatory protein, and suggests that further investigation into its potential use in the diagnosis and prognosis of AIS is warranted. [Copyright &y& Elsevier]

Blue-color-emitting organic semiconductors are of significance for organic light-emitting diodes (OLEDs). In this study, through Suzuki coupling polymerization, three 1,4-naphthalene-based copolymers—namely, PNP(1,4)-PT, PNP(1,4)-TF, and PNP(1,4)-ANT—were designed and synthesized. The variation of comonomers, phenothiazine (PT), triphenylamine substituted fluorene (TF), and anthanthrene (ANT), effectively tuned the emitting color and device performance of poly(9-vinyl carbazole) (PVK)-based OLEDs. Especially, the polymer PNP(1,4)-TF, bearing perpendicular aryl side groups, showed a most twisted structural geometry, which enabled an ultra-high thermal stability and a best performance with blue emitting in PVK-host-based OLEDs. Overall, in this work, we demonstrate a promising blue-color-emitting polymer through structural geometry manipulation. [ABSTRACT FROM AUTHOR]

• The photophysics correlated with morphology of perovskite films in ambient condition is reported. • Our findings provide deep insights into the fundamental optical processes in perovskite films. • Such a insight is useful for advancement of air processable lead based optoelectronic devices. We report room temperature excitation intensity dependent charge carrier dynamics in solvent-annealed organo-metal halide perovskite semiconductor CH 3 NH 3 PbI 3 thin film using steady state and time resolved photoluminescence studies. The average lifetime of these solvent annealed films does not vary significantly with excitation fluence confirming the formation of almost defect free perovskite crystallites. The photocarrier dynamics are well described by a simple rate equation. The local reduction of shallow trap densities as observed in PL dynamics was correlated with scanning electron microscopy (SEM) and X-ray spectroscopy. The observed photophysical investigation and morphology study suggests that anti-solvent method as a potential approach for CH 3 NH 3 PbI 3 perovskite solar cell fabrication under ambient condition. A prototype all air processed anti-solvent method based stable perovskite device yielded the efficiency of 7.54% with J SC value of 14.21 mA/cm2 and V OC of 810 mV. [ABSTRACT FROM AUTHOR]

Traditional full-color displays typically use a pixel layout with three side-by-side subpixels emitting red (R), green (G), and blue (B) colors. However, this configuration limits the resolution especially in augmented reality (AR) and virtual reality (VR) applications. To address the issue of low pixel density in display technology, this study demonstrated vertically stacked three-terminal (3-T) bottom-emitting tandem OLEDs (sOLED). These OLEDs offer color tunability, facilitated by individually controlled colour units. This study demonstrates two combinations: G+B and R+G. Incorporating three generations of OLED's materials phosphorescent (R), thermally activated delayed fluorescence (TADF) (G), and hyperfluorescent (B). The OLEDs achieve maximum current efficiencies of approximately 11 cd/A, 52.4 cd/A, and 40.7 cd/A for R, G, and B, respectively, in their respective tandem configurations. A wide range of colors can be achieved by blending G+B and R+G color spectrum by adjusting the voltage of independent color unit. The optimal mix results in a fine cyan color with CIE coordinates (0.273,0.5) in G+B sOLED and a warm white with CIE coordinates (0.416,0.518)in R+G sOLED. This work demonstrate a better performing 3-T sOLED utilizing three different generations OLED materials, offering an individual control within a single pixel providing enhanced pixel density for display technology., (© 2024 Wiley‐VCH GmbH.)

The efficiency of an organic solar cell is highly dependent on the complex, interpenetrating morphology, and molecular order within the composite phases of the bulk heterojunction (BHJ) blend. Both these microstructural aspects are strongly influenced by the processing conditions and chemical design of donor/acceptor materials. To establish improved structure-function relationships, it is vital to visualize the local microstructural order to provide specific local information about donor/acceptor interfaces and crystalline texture in BHJ blend films. The visualization of nanocrystallites, however, is difficult due to the complex semi-crystalline structure with few characterization techniques capable of visualizing the molecular ordering of soft materials at the nanoscale. Here, it is demonstrated how cryo-electron microscopy can be utilized to visualize local nanoscale order. This method is used to understand the distribution/orientation of crystallites in a BHJ blend. Long-range (>300 nm) texturing of IEICO-4F crystallites oriented in an edge-on fashion is observed, which has not previously been observed for spin-coated materials. This approach provides a wealth of quantitative information about the texture and size of nanocrystallites, which can be utilized to understand charge generation and transport in organic film. This study guides tailoring the material design and processing conditions for high-performance organic optoelectronic devices., (© 2024 The Authors. Small Methods published by Wiley‐VCH GmbH.)

Light emission from organoboron compounds of Schiff bases is found to depend strongly on their chemical structure. Two of these compounds (OB1 and OB2), which contain a benzene ring between the Schiff base moieties, exhibit weak fluorescence in methanol, with marked viscosity dependence. Fluorescence lifetimes of these compounds are in picosecond timescale, as determined by femtosecond optical gating (FOG). A significant enhancement in fluorescence intensity and lifetime is observed at 77 K, indicating the operation of an activated nonradiative process. Using fluorescence lifetime imaging microscopy (FLIM), OB1 and OB2 are shown to be potential membrane probes. The third (OB3), which is devoid of this benzene ring, exhibits relatively stronger fluorescence with nanosecond lifetimes at room temperature. No viscosity dependence is observed in this case. The emission spectrum at 77 K is markedly more intense and exhibits an additional red shifted structured feature, which persists for a few seconds. Hence, OB3 seems to have greater promise not only as fluorescent probe but also for light harvesting. The marked improvement of the light emission properties of OB3 compared with OB1 and OB2 is likely to serve as a pointer for the design of Schiff base-derived organoboron luminophores with diverse potential applications., (© 2024 American Society for Photobiology.)

Ionic cocrystals with hydrogen bonding can form exciting materials with enhanced optical and electronic properties. We present a highly moisture-stable ammonium salt cocrystal [CH 3 C 6 H 4 CH(CH 3 )NH 2 ][CH 3 C 6 H 4 CH(CH 3 )NH 3 ][PF 6 ] ( ( p -TEA)( p -TEAH)·PF 6 ) crystallizing in the polar monoclinic C 2 space group. The asymmetry in ( p -TEA)( p -TEAH)·PF 6 was induced by its chiral substituents, while the polar order and structural stability were achieved by using the octahedral PF 6 - anion and the consequent formation of salt cocrystal. The ferroelectric properties of ( p -TEA)( p -TEAH)·PF 6 were confirmed through P-E loop measurements. Piezoresponse force microscopy (PFM) enabled the visualization of its domain structure with characteristic "butterfly" and hysteresis loops associated with ferro- and piezoelectric properties. Notably, ( p -TEA)( p -TEAH)·PF 6 exhibits a large electrostrictive coefficient ( Q 33 ) value of 2.02 m 4 C -2 , higher than those found for ceramic-based materials and comparable to that of polyvinylidene difluoride. Furthermore, the composite films of ( p -TEA)( p -TEAH)·PF 6 with polycaprolactone (PCL) polymer and its gyroid-shaped 3D-printed composite scaled-up device, 3DP- Gy , were prepared and evaluated for piezoelectric energy-harvesting functionality. A high output voltage of 22.8 V and a power density of 118.5 μW cm -3 have been recorded for the 3DP- Gy device. Remarkably, no loss in voltage outputs was observed for the ( p -TEA)( p -TEAH)·PF 6 devices even after exposure to 99% relative humidity, showcasing their utility under extremely humid conditions.

Within the burgeoning field of electronic materials, B-N Lewis acid-base pairs, distinguished by their partial charge distribution across boron and nitrogen centers, represent an underexplored class with significant potential. These materials exhibit inherent dipoles and are excellent candidates for ferroelectricity. However, the challenge lies in achieving the optimal combination of hard-soft acid-base pairs to yield B-N adducts with stable dipoles. Herein, we present an enantiomeric pair of B-N adducts [ R/S C 6 H 5 CH(CH 3 )NH 2 BF 3 ] ( R/S MBA-BF 3 ) crystallizing in the polar monoclinic P2 1 space group. The ferroelectric measurements on R MBA-BF 3 gave a rectangular P-E hysteresis loop with a remnant polarization of 7.65 μC cm -2 , a value that aligns with the polarization derived from the extensive density-functional theory computations. The PFM studies on the drop-casted film of R MBA-BF 3 further corroborate the existence of ferroelectric domains, displaying characteristic amplitude-bias butterfly and phase-bias hysteresis loops. The piezoelectric nature of the R MBA-BF 3 was confirmed by its direct piezoelectric coefficient (d 33 ) value of 3.5 pC N -1 for its pellet. The piezoelectric energy harvesting applications on the sandwich devices fabricated from the as-made crystals of R MBA-BF 3 gave an open circuit voltage (V PP ) of 6.2 V. This work thus underscores the untapped potential of B-N adducts in the field of piezoelectric energy harvesting., (© 2024 Wiley‐VCH GmbH.)

Photophysics of a blue light-emitting fluorescent random copolymer, consisting of arylated polydioctylfluorene (aryl-F8), polydioctylfluorene (F8), and amine comonomers in a ratio of 80:15:5 is reported. In a solution of 10 -6 M, solvatochromism in absorption and photoluminescence (PL) is observed with an increased lifetime of PL as the polarity of the solvent increases. Dual fluorescence is observed in the 10 -9 M diluted solution, comprising a structured emission from a localized state in the aryl-F8 comonomer and a broad emission peak from the charge-transfer (CT) state at a lower energy. Emission wavelength-dependent time-resolved photoluminescence studies in different polar media confirm the presence of the emissive intrachain CT state in this copolymer. Analyzing the PL decay kinetics, we calculated the formation rate of the intrachain CT state to be ∼3.0 × 10 9 s -1 . Repopulation of the localized state from the CT state is observed in the lower polarity medium with a rate of 7 × 10 8 s -1 , which is almost absent for the large Stokes-shifted CT emission in the higher polarity medium. Along with the fundamental understanding of the photophysics of the random copolymer, this study suggests that the emission spectrum can be tailored by the concentration of polymer and the polarity of surrounding media.

Triplet-triplet annihilation-induced delayed emission provides a pathway for investigating triplets via emission spectroscopy. This bimolecular annihilation depends directly on the transport properties of triplet excitons in disordered organic semiconductors. Photoluminescence (PL) imaging is a direct method for studying exciton and charge-carrier diffusivity. However, most of these studies neglect dispersive transport. Early time scale measurements using this technique can lead to an overestimation of the diffusion coefficient ( D T ) or diffusion length ( L d ). In this study, we investigated the time-dependent triplet D T using PL imaging. We observed an overestimation of L d in classical delayed PL imaging, often 1 order of magnitude higher than the actual L d value. We compared various thicknesses of polymeric thin films to study the dispersive nature of triplet excitons. Transient analysis of delayed PL imaging and steady state imaging reveals the importance of considering the time-dependent nature of D T for the triplet excitons in disordered electronic materials.

Silver cluster-based solids have garnered considerable attention owing to their tunable luminescence behavior. While surface modification has enabled the construction of stable silver clusters, controlling interactions among clusters at the molecular level has been challenging due to their tendency to aggregate. Judicious choice of stabilizing ligands becomes pivotal in crafting a desired assembly. However, detailed photophysical behavior as a function of their cluster packing remained unexplored. Here, we modulate the packing pattern of Ag 12 clusters by varying the nitrogen-based ligand. CAM-1 formed through coordination of the tritopic linker molecule and NC-1 with monodentate pyridine ligand; established via non-covalent interactions. Both the assemblies show ligand-to-metal-metal charge transfer (LMMCT) based cluster-centered emission band(s). Temperature-dependent photoluminescence spectra exhibit blue shifts at higher temperatures, which is attributed to the extent of the thermal reverse population of the S 1 state from the closely spaced T 1 state. The difference in the energy gap (ΔE ST ) dictated by their assemblies played a pivotal role in the way that Ag 12 cluster assembly in CAM-1 manifests a wider ΔE ST and thus requires higher temperatures for reverse intersystem crossing (RISC) than assembly of NC-1. Such assembly-defined photoluminescence properties underscore the potential toolkit to design new cluster- assemblies with tailored optoelectronic properties., (© 2023 Wiley-VCH GmbH.)

Contact resistance ( R C ) in organic devices originates from a mismatch in energy levels between injecting electrodes and organic semiconductors (OSCs). However, the microscopic effects governing charge transfer between electrodes and the OSCs have not been analyzed in detail. We fabricated transistors with different OSCs (PTB7, PCDTBT, and PTB7-Th) and electrodes (MoO 3 , Au, and Ag) and measured their contact resistance. Regardless of the electrodes, devices with PTB7-Th exhibit the lowest values of R C . To explain the trends observed, first-principles computations were performed on contact interfaces based on the projector operator diabatization method. Our results revealed that differences in energy levels and the electronic couplings between OSCs' highest occupied molecular orbitals and vacant states on the electrodes influence device R C . Further, based on values obtained from the first-principles, the rate of charge transfer between OSCs and electrodes is calculated and found to correlate strongly with trends in R C for devices with different OSCs. We thus show that device R C is governed by the feasibility of charge transfer at the contact interface and hence determined by energy levels and electronic coupling among orbitals and states located on OSCs and electrodes.

Indoor organic photovoltaics (OPVs) have shown great potential application in driving low-energy-consumption electronics for the Internet of Things. There is still great room for further improving the power conversion efficiency (PCE) of indoor OPVs, considering that the desired morphology of the active layer to reduce trap-assisted recombination and voltage losses and thus simultaneously enhance the fill factor (FF) and open-circuit voltage for efficient indoor OPVs remains obscure. Herein, by optimizing the bulk and interface morphology via a layer-by-layer (LBL) processing strategy, low leakage current and low non-radiative recombination loss can be synergistically achieved in PM6:Y6-O based devices. Detailed characterizations reveal the stronger crystallinity, purer domains and ideal interfacial contacts in the LBL devices compared to their bulk-heterojunction (BHJ) counterparts. The optimized morphology yields a reduced voltage loss and an impressive FF of 81.5%, and thus contributes to a high PCE of 31.2% under a 1000 lux light-emitting diode (LED) illumination in the LBL devices, which is the best reported efficiency for indoor OPVs. Additionally, this LBL strategy exhibits great universality in promoting the performance of indoor OPVs, as exemplified by three other non-fullerene acceptor systems. This work provides guidelines for morphology optimization and synergistically promotes the fast development of efficient indoor OPVs.

Strategically doped metal oxide nanomaterials signify a rapidly growing genre of functional materials with a wide range of practical applications. Copper vanadate (CuV) represents one such highly active system, which has been rarely explored following its doping with an abundant first-row transition metal. Here, we have developed a series of CuV samples with varying cobalt(ii) doping concentrations deploying a relatively simple solid state synthetic procedure. Among the samples, the 10% Co(ii)-doped CuV (Co 10% -CuV) exhibited excellent reactivity for both the H 2 evolution reaction (HER) and glycerol oxidation reaction (GOR) in an alkaline aqueous medium (pH 14.0) during cathodic and anodic scans, respectively. During this dual-active catalysis, surface-immobilized Co 10% -CuV operates at exceptionally low overpotentials of 176 mV and 160 mV for the HER and GOR, respectively, while achieving 10 mA cm 2 current density. The detailed spectroscopic analysis revealed the formation of formate as the major product during the GOR with a faradaic efficiency of >90%. Therefore, this Co 10% -CuV can be included on either side of a two-electrode electrolyzer assembly to trigger a complete biomass-driven H 2 production, establishing an ideal carbon-neutral energy harvest process., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

The burgeoning noncovalent interactions between π-acidic aromatic surfaces and anions have been recently shown to have unique functional relevance in anion transport, ion sensing, and organocatalysis. Despite its potential to instigate charge-transfer (CT) states, modulation of the emission features by toggling between the excited states using anion-π interactions is not yet explored. On the other hand, excited states with CT characteristics play an important role in the ambient triplet harvesting of organic chromophores. In this context, herein we propose an anion-π-based molecular design for the introduction of emissive singlet and triplet CT excited states, thereby expanding the functional scope of these weak supramolecular interactions. In the present study, we investigate the anion-π-induced emission from the singlet ( 1 CT) and triplet ( 3 CT) CT states of a dibromo dicationic pyromellitic diimide derivative. Remarkably, we accomplish dual room temperature phosphorescence emission from the anion-π-mediated 3 CT state along with the locally excited triplet state ( 3 LE) in solution phase using an organic-inorganic supramolecular scaffolding strategy. Comprehensive steady-state and time-resolved spectroscopy along with theoretical calculations provide detailed insights into the excited-state manifolds of phosphor. We envisage that the present study will expedite new molecular designs based on weak intermolecular interactions for the excited-state engineering of organic chromophores to facilitate ambient triplet harvesting and CT emission.

2,2'-Bipyridine based bisphosphine [C 5 H 3 N{N(H)CH 2 PPh 2 }] 2 (1) and its bischalcogenide derivatives [C 5 H 3 N{N(H)CH 2 P(E)Ph 2 }] 2 (2, E = O; 3, E = S; 4, E = Se) were synthesized, and further reacted with BF 3 ·Et 2 O/Et 3 N to form doubly B ← N fused compounds [C 5 H 3 N(BF 2 ){NCH 2 P(E)Ph 2 }] 2 (5, E = O; 6, E = S; 7, E = Se) in excellent yields. The influence of the PE bonds on the electronic properties of the doubly B ← N fused systems and their structural features were investigated in detail, supported by extensive experimental and computational studies. Compound 6 exhibited a very high quantum yield of ϕ = 0.56 in CH 2 Cl 2 , whereas compound 7 showed a least quantum yield of ϕ = 0.003 in acetonitrile. Density functional theory (DFT) calculations demonstrated that the LUMO/HOMO of compounds 5-7 mostly delocalized over the entire π-conjugated frameworks. The involvement of PE bonds in the HOMO energy level of these compounds follows the order: PO < PS < PSe. Time-correlated single photon counting (TCSPC) experiments of compounds 5-7 revealed the singlet lifetime of 4.26 ns for 6, followed by 4.03 ns for 5 and a lowest value of 2.18 ns ( τ 1 ) and 0.47 ns ( τ 2 ) with a double decay profile for 7. Our findings provide important strategies for the design of highly effective B ← N bridged compounds and tuning their photophysical properties by oxidizing phosphorus with different chalcogens. Compounds 5 and 6 have been employed as green emitters ( λ em = 515 nm) in fluorescent organic light-emitting diodes (OLEDs). For compound 5, doped into the poly(9-vinylcarbazole) (PVK) matrix with 5 wt% doping concentration, nearly 90 Cd m -2 luminance with 0.022% external quantum efficiency (EQE) was achieved. The best performance was observed for compound 6 doped into PVK by 1 wt% having a maximum luminance of 350 Cd m -2 and a similar EQE value.

The origin of broadband emission is studied using temperature-dependent time-resolved photoluminescence (PL) spectra for two-dimensional (2D) layered halide perovskites (i.e., (PEA) 2 PbBr 4 = phenylethylammonium lead bromide and (PEA) 2 PbI 4 = phenylethylammonium lead iodide) semiconductors. Both perovskite systems show only a single peak exciton emission at room temperature, which becomes multipeak exciton emissions at low temperatures. For temperatures below 100 K, the (PEA) 2 PbBr 4 film gives broad PL emission, Stokes shifted by 750 meV from narrow exciton emission peaks, whereas the (PEA) 2 PbI 4 film does not show any broad emission. Kinetics of various peaks could provide useful insight to propose a consistent energy level scheme associated with a barrier (PEA) and well (PbX 6 4- ) material system's electronic states. This broad emission in (PEA) 2 PbBr 4 perovskite is observed due to coupling of triplet states in the inorganic well (PbBr 6 4- ) and organic barrier (PEA) layer, which is in contrast to a proposed model based on self-trapped exciton.

Voltage losses (Δ V OC ) are a crucial limitation for the performance of excitonic organic solar cells (OSCs) and can be estimated by two approaches─the radiative limit and the Marcus charge-transfer (MCT) model. In this work, we show that combining the radiative limit and MCT models for voltage loss calculations provides useful insights into the physics of emerging efficient OSCs. We studied nine different donor-acceptor systems, wherein the power conversion efficiency ranges from 4.4 to 14.1% and Δ V OC varies from 0.55 to 0.95 V. For these state-of-the-art devices, we calculated the Δ V OC using the radiative limit and the MCT model. Furthermore, we combined both models to derive new insights on the origin of radiative voltage losses (Δ V rad ) in OSCs. We quantified the contribution in Δ V rad due to the bulk intramolecular (S 1 ) disorder and interfacial intermolecular (CT) disorder by revisiting the spectral regions of interest for OSCs. Our findings are in agreement with the expected relationship of V OC with Urbach energy ( E U ), which suggests that the low E U is beneficial for reduced losses. However, unprecedentedly, we also identify a universal, almost linear relationship between the interfacial disorder (λ) and Δ V rad . We believe that these results can be exploited by the organic photovoltaic (OPV) community for the design of new molecules and a combination of donor-acceptors to further improve OSCs.

The energy band gaps of Pb halide perovskites are higher than the optimal band gap required for single-junction solar cells, governed by the Shockley-Queisser radiative limit. The pure Sn and Pb-Sn mixed-based perovskites have drawn significant attention due to their ability to lead to lower band gaps and open a new door for all perovskite tandem applications. There has been continuous progress toward the rapid improvement in the power conversion efficiency of Sn and Pb-Sn mixed-based perovskite solar cells (PSCs). Along with efforts for efficiency, it is worth analyzing the in-depth recombination dynamics for further development of Sn-based PSCs. The lower bimolecular recombination rate constant ( k ) is often attributed to the high performance of PSCs. Herein, we study the role of "B" cations in charge carrier recombination dynamics (CCRD) of ABX 3 (A = MA + , FA + , and Cs + ; B = Pb 2+ , Sn 2+ , and X = I - )-based PSCs. We fabricated p-i-n configuration-based FA 0.95 Cs 0.05 PbI 3 (pure Pb), MA 0.20 FA 0.75 Cs 0.05 SnI 3 (pure Sn), and (MAPbI 3 ) 0.4 (FASnI 3 ) 0.6 (Pb-Sn mixed) PSCs and compared the CCRD of all the three PSCs. We optimized the Sn-based perovskite thin film (pure Sn) in terms of moisture and thermal stability in order to minimize the error due to perovskite degradation. We note that despite having lower open-circuit voltage ( V OC ), a pure Sn-based PSC shows lower k than that of Pb-Sn mixed and pure Pb-based PSCs, which is a contradictory result. This slow relaxation lifetime of the charge carrier in Sn-based PSCs can be correlated with recombination through the defect states without introducing the quasi-Fermi-level splitting. Furthermore, our results suggest that the rate law of charge carrier decay has nonlinear dependence of k on n in Sn-based PSCs, whereas it is linear in the other two cases.

Triplet harvesting under ambient conditions plays a crucial role in improving the luminescence efficiency of purely organic molecular systems. This requires elegant molecular designs that can harvest triplets either via room temperature phosphorescence (RTP) or by thermally activated delayed fluorescence (TADF). In this context, here we report a donor core-substituted pyromellitic diimide (acceptor) derivative as an efficient charge-transfer molecular design from the arylene diimide family as a triplet emitter. Solution-processed thin films of carbazole-substituted CzPhPmDI display both RTP- and TADF-mediated twin emission with a long lifetime and high efficiency under ambient conditions. The present study not only sheds light on the fundamental photophysical process involved in the triplet harvesting of donor-acceptor organic systems, but also opens new avenues in exploring an arylene diimide class of molecules as potential organic light-emitting materials.

In this work, a unique comprehensive and comparative analysis of photoinduced charge generation, recombination kinetics, and energy losses has been carried out to study the effect of different fullerene-based acceptors (FBAs) and nonfullerene acceptors (NFAs) on the performance of organic solar cells (OSCs). For this, different FBAs, specifically ICBA, PC60BM, and PC70BM, and NFAs, namely, ITIC, IT-4F, and IEICO-4F, were employed independently along with a particular donor polymer, PBDB-T, to fabricate bulk heterojunction OSCs and their performances have been compared. This donor molecule is known to give similar power conversion efficiency (PCE) with FBAs and NFAs and hence is ideal for comparative studies. The origin of the higher PCE of NFA-based OSCs vs FBA-based OSCs is analyzed in terms of spectral coverage, charge generation, recombination, and energy loss. It is found that the energy loss (Δ E loss ) is ∼0.8 to 1 eV for FBA-based OSCs, while it is 0.5-0.7 eV for NFA-based OSCs. Interestingly, for the PBDB-T:IEICO-4F-based system, energy losses due to charge generation (Δ E CT ) are ∼0 eV and therefore this system has minimum Δ E loss among all of the studied devices. Providing a systematic, comprehensive, and comparative outlook, our study may further be extended to new upcoming NFA systems and beyond the donor system used in this work.

Perovskite light-emitting diodes have almost reached the threshold for potential commercialization within a few years of research. However, there are still some unsolved puzzles such as large ideality factor and the presence of large negative capacitance especially at the low-frequency regime yet to be addressed. Here, we have fabricated a methylammonium lead tri-bromide perovskite n-i-p structure for light-emitting diodes from a smooth and textured emissive layer and demonstrated for the first time that these two factors are strongly dependent on the perovskite film morphology. Bias-dependent capacitance measurement also reveals the transition between negative to positive capacitance in textured films at the low-frequency regime. We have observed an anomalous capacitive behavior at the mid-frequency regime in smooth perovskite films but not in textured films. The relatively large ideality factor and anomalous capacitive behavior observed in perovskite light-emitting diodes are due to the presence of strong coupling between ions and electrons near the electrode interface. Therefore, the ideality factor and anomalous capacitance at the mid-frequency regime can be decreased by minimizing electronic-ionic coupling in textured perovskite films, while light outcoupling can be improved significantly.

Objectives: We compared the concentrations of the proinflammatory cytokine interleukin-2 (IL-2) with the anti-inflammatory cytokine interleukin-10 (IL-10) in serial serum samples from improved and expired acute ischemic stroke (AIS) patients to determine their prognostic usefulness., Materials and Methods: Blood from AIS patients (n = 17) admitted within 24 h of the onset of symptoms were collected at admission and 24, 48, 72, and 144 h after admission. Pro- and anti-inflammatory cytokines were measured by enzyme-linked immunosorbant assay., Results: IL-2 levels were elevated in serum samples from AIS patients collected at 0 (0.97, P < 0.01) and 24 h (1.011, P < 0.01). IL-2 concentrations gradually decreased at subsequent time-points (48, 72, and 144 h samples, 0.324, P < 0.05) in patients who improved (n = 13), but not in those who expired (n = 4). Similarly, a decrease in IL-10 levels was observed in serum samples from AIS patients who improved at 24 h (0.180, P < 0.05), followed by significant increases at 72 h (0.97, P < 0.01 vs. control) and 144 h (1.38, P < 0.01)., Conclusion: The levels of IL-2 and IL-10 correlate well with outcome in AIS patients and may be useful in prognosis.