Open Circuit Voltage Values Research Articles

Exploring the Potential of Linear π-Bridge Structures in a D-π-A Organic Photosensitizer for Improved Open-Circuit Voltage.

We present the design, synthesis, and evaluation of novel metal-free photosensitizers based on D-π-A structures featuring tri-arylamine as an electron donor, cyanoacrylic acid as an anchoring group, and substituted derivative π-bridges including 9,9-dimethyl-9H-fluorene, benzo[b]thiophene, or naphtho [1,2-b:4,3-b']dithiophene. The aim of the current research is to unravel the relationship between chemical structure and photovoltaic performance in solar cell applications by investigating the properties of these organic sensitizers. The newly developed photosensitizers displayed variations in HOMO-LUMO energy gaps and photovoltaic performances due to their distinct π-bridge structures and exhibited diverse spectral responses ranging from 343 to 490 nm. The t-shaped and short linear photosensitizers demonstrated interesting behaviors in dye-sensitized solar cells, such as the effect of the molecular size in electron recombination. The study showed that a t-shaped photosensitizer with a bulky structure reduced electron recombination, while short linear photosensitizers with a smaller molecular size resulted in a higher open-circuit voltage value and enhanced photovoltaic performance. Impedance analysis further supported the findings, highlighting the influence of dye loading and I3- ion surface passivation on the overall performance of solar cells. The molecular design methodology proposed in this study enables promising photovoltaic performance in solar cells, addressing the demand for highly efficient, metal-free organic photosensitizers.

Efficiency enhancement above 31 % of Sb2Se3 solar cells with optimizing various BSF layer

Recent advancements in solar technology have increased the acceptance of antimony selenide (Sb2Se3) due to its advantageous properties. This study aims to enhance the performance of the Sb2Se3 structure by using tungsten disulfide (WS2) as the window layer and copper zinc tin selenide (CZTSe) as the back surface field (BSF) layer, utilizing SCAPS-1D (solar cell and capacitance simulator). An initial investigation of seven potential BSF layers identified CZTSe as the best choice for improving power conversion efficiency (PCE). By carefully simulating various parameters, including the thicknesses of the absorber and window layers, donor and acceptor densities, defect density, shunt resistance, and series resistance, significant performance improvements were achieved. Without the BSF layer, the cell showed a PCE of 28.20 % along with specific values for short circuit current density (JSC), open-circuit voltage (VOC), and fill factor (FF). The addition of the BSF layer increased the PCE to 31.52 %, along with enhancements in JSC, VOC, and FF. These results highlight the potential of this approach for developing high-performance Sb2Se3 based solar cells, surpassing conventional designs.

Current-Voltage (i-V) characteristics of electrolyte-supported (NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF) solid oxide electrolysis cell during CO2/H2O co-electrolysis

Solid oxide electrolysis cells (SOECs) stabilize CO2 emissions by converting CO2/H2O into synfuel. Current-Voltage (i-V) characteristics of an electrolyte-supported button cell (NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF) were measured as a function of temperature, water vapor concentration, and CO2 gas concentrations. The cell microstructure was characterized by the Field Emission Scanning Electron Microscope (FE-SEM). FE-SEM micrographs depict that the electrolyte layer is relatively dense, and porous fuel and air electrode layers are well adhered to the electrolyte. The i-V curves were obtained at a scan rate of 0.02 Vs−1 from 0.3 to 1.5 V. Electrolysis current density increases as the temperature increases. SOEC performance increases, but SOFC performance decreases with increased water vapor concentration. Electrolysis current densities decrease as the CO2 concentration increases. The i-V characteristics show only ohmic polarization under fuel-lean and fuel-rich conditions. At optimal conditions, current density values at 800 °C/1.5 V are -174, -187, and -195 mA cm−2 for 5 %H2O, 30 %CO2, and 30 %CO2/5 %H2O co-electrolysis. At 800 °C, open-circuit voltage (OCV) values for H2O, CO2, and co-electrolysis are 0.906, 0.891, and 0.885 V, respectively. The electrolysis area-specific resistances (ASRs) give information on the reduction of CO2 or H2O, forming CO or H2, respectively. At optimal conditions, ASR values are 3.43, 3.29, and 3.18 Ω cm2 for H2O, CO2, and co-electrolysis, respectively. Co-electrolysis has a lower ASR value than pure H2O and CO2 electrolysis, indicating that H2O and CO2 are involved in the electrochemical processes.

Ligand Homogenized Br-I Wide-Bandgap Perovskites for Efficient NiOx-Based Inverted Semitransparent and Tandem Solar Cells.

Phase heterogeneity of bromine-iodine (Br-I) mixed wide-bandgap (WBG) perovskites has detrimental effects on solar cell performance and stability. Here, we report a heterointerface anchoring strategy to homogenize the Br-I distribution and mitigate the segregation of Br-rich WBG-perovskite phases. We find that methoxy-substituted phenyl ethylammonium (x-MeOPEA+) ligands not only contribute to the crystal growth with vertical orientation but also promote halide homogenization and defect passivation near the buried perovskite/hole transport layer (HTL) interface as well as reduce trap-mediated recombination. Based on improvements in WBG-perovskite homogeneity and heterointerface contacts, NiOx-based opaque WBG-perovskite solar cells (WBG-PSCs) achieved impressive open-circuit voltage (Voc) and fill factor (FF) values of 1.22 V and 83%, respectively. Moreover, semitransparent WBG-PSCs exhibit a PCE of 18.5% (15.4% for the IZO front side) and a high FF of 80.7% (79.4% for the IZO front side) for a designated illumination area (da) of 0.12 cm2. Such a strategy further enables 24.3%-efficient two-terminal perovskite/silicon (double-polished) tandem solar cells (da of 1.159 cm2) with a high Voc of over 1.90 V. The tandem devices also show high operational stability over 1000 h during T90 lifetime measurements.

Charge/Discharge Simulation Models of LiFePO4 Cells in MATLAB/Simulink

Lithium (Li) cells find widespread applications, particularly in electric vehicles their dynamic characteristics are often represented through equivalent circuit models. In this study, two different second-order equivalent circuit models of LiFePO4 cells are modeled and simulated in MATLAB/Simulink. The first model exhibits capacity changes based on drawn current, while the second assumes constant capacity. The analysis of the simulations results focuses on key parameters such as State of Charge (SOC), Open Circuit Voltage (OCV), and terminal voltage (VT). Comparative evaluations between the first and second cell models utilize formulas derived from prior experimental cell studies. Specifically, a 0.0155% variance in SOC, a 0.00003% difference in OCV, and a 0.00003% distinction in VT were observed between the two models during discharge. A similar assessment during charging observed an error of 0.0447% in SOC, 0.00007% in OCV, and 0.00003% in VT. Furthermore, the discharge process in the first model demonstrates lower SOC, OCV, and VT values, contrasting with higher values during charging. Despite these variances, the study concludes that both models yield similar results, establishing them as viable references for equivalent circuit representations of Lithium cells.

Synthesis and Photovoltaic Performance of β-Amino-Substituted Porphyrin Derivatives.

New β-amino-substituted porphyrin derivatives bearing carboxy groups were synthesized and their performance as sensitizers in dye-sensitized solar cells (DSSC) was evaluated. The new compounds were obtained in good yields (63-74%) through nucleophilic aromatic substitution reactions with 3-sulfanyl- and 4-sulfanylbenzoic acids. Although the electrochemical studies indicated suitable HOMO and LUMO energy levels for use in DSSC, the devices fabricated with these compounds revealed a low power conversion efficiency (PCE) that is primarily due to the low open-circuit voltage (Voc) and short-circuit current density (Jsc) values.

Rational and green functionalization of B,N-C60 by DNA bases devised as incredible electron transport compounds for perovskite photovoltaic devices

Environmentally benign materials were devised to be employed as excellent electron transporting layers (ETLs) in perovskite solar cell (PSC) devices. They were based on B,N-C60 fullerene functionalized with a pyrrolidine ring (fulleropyrrolidine) attached to a thiophene ring and a cyanoethyl group (named F-B,N-C60), which was further functionalized by four deoxyribonucleic acid (DNA) bases from their exocyclic N (in NH/NH2 groups) or endocyclic N atoms. To investigate electronic, optical, structural, and electron mobility characteristics of such compounds, density functional theory (DFT) calculations were done. Lowest unoccupied molecular orbital (LUMO) levels of all ETL samples were deeper than conduction band of perovskite CsFAMAPbIBr in PSCs (except for the two samples F-B,N-C60-G1 and F-B,N-C60-G2) that simply injected electrons from CsFAMAPbIBr toward Ag electrode. Highly extraordinary electron mobilities achieved for B,N-C60 functionalized fullerenes were changed from 5.1245 to 106.2272 cm2V−1s−1 that were about 1016-1018 times larger compared to that of B,N-C60 (3.1844×10−16 cm2V−1s−1). Among all ELs, the two samples F-B,N-C60-G1 and F-B,N-C60-G2 displayed very much larger photovoltaic parameters than the rest of B,N-C60 functionalized ETLs. High fill factor (FF), power conversion efficiency (PCE), and open circuit voltage (VOC) values were measured for the PSCs with the devised ETLs in ranges of 0.795–0.893, 8.4522–22.887%, and 0.468–1.129 V, respectively, establishing they could be applied as remarkable ETL materials for photovoltaics.

BC cone-shaped anodes for lithium-ion batteries

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.

Performance test of Zn-astaxanthin complex-sensitized solar cell: effect of light intensity on open-circuit voltage and short-circuit current values.

The sensitizer is one of the most essential dye-sensitized solar cell (DSSC) components. In the present research, a Zn-astaxanthin complex was investigated as a sensitizer, compared to pure astaxanthin. The complex with a 1:1 mole ratio between astaxanthin and Zn2+ was synthesized in a reflux reactor at 37-60 °C. The product was analyzed using Proton Nuclear Resonance (1H-NMR), which indicates the presence of chelate formation between Zn2+ with two atoms of oxygen on the terminal cyclohexane ring of astaxanthin. The interaction of sensitizers (astaxanthin and Zn-astaxanthin) on the photoelectrode surface in this study was analyzed using a Fourier Transform Infra-Red (FTIR) and Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS). The FTIR spectra of photoelectrode immersed in Zn-astaxanthin show peaks of C=O stretching and vibration -OH group at 1730 and 1273 cm-1, respectively, and H-C-H stretching vibration with high intensity in 2939, 2923, and 2853 cm-1. The UV-Vis DRS analysis shows the band gap of photoelectrode (PE), photoelectrode immersed in astaxanthin (PE/astaxanthin), and Zn-astaxanthin (PE/Zn-astaxanthin) are 3.19, 1.65, and 1.59 eV, respectively. Under illumination intensity of 300 W/m2, the maximum energy conversion efficiency of DSSC with Zn-astaxanthin as sensitizer is (0.03 ± 0.0022)%, higher than DSSC with astaxanthin as sensitizer ((0.12 ± 0.0052)%). Up to 70 h of illumination, DSSC with Zn-astaxanthin as a sensitizer also has better stability than astaxanthin-based DSSC.

Nitrogen-doped graphene quantum dots/ polyvinyl alcohol nanocomposite for photon management: Application in CIGS photovoltaic cells

The efficiency (η) of copper indium gallium selenide (CIGS) solar cells has been hampered by absorption losses that happen within the ZnO and CdS layers. A photon downconversion layer created from polyvinyl alcohol (PVA) and nitrogen-doped graphene quantum dots (NGQDs) composite (NGQDs/PVA) was implemented on the top of the cell to overcome this obstacle. Notably, the NGQDs/PVA layers, prepared at spin speeds of 3000, 4000, and 5000 rpm, exhibited optimal characteristics, demonstrating superior light absorption at low wavelengths along with elevated transmittance at longer wavelengths. The η was found to be highest for the layer prepared at 4000 rpm, accompanied by elevated values of short-circuit current (Jsc), open-circuit voltage (Voc), and fill factor (FF). Consequently, Cell #2 incorporating the champion NGQDs/PVA layer outperformed all other CIGS photovoltaic cells, showcasing an impressive enhancement of 8.96 % in Jsc, 1.62 % in Voc, 2.03 % in FF, and an overall η of 11.51 %. This champion cell significantly improves the performance of CIGS photovoltaics.

Active cooling of a photovoltaic module in hot-ambient temperatures: theory versus experiment

Abstract The performance improvement of a PV-module is investigated theoretically and experimentally in a long-term research-plan via module cooling by different approaches including passive, active, and evaporative cooling as well as water cooling for the same module. In the present paper, the investigation is conducted to decide on the suitability of active-cooling of the module in hot-ambient temperatures. A module without cooling is used as a base case for comparison against cooled modules with and without fins attached to the module’s rear-surface and extended down in an air-cooling duct underneath the module. At first, a theoretical study of heat transfer through the module is conducted to investigate how the calculated cell temperature and module output power are influenced by the air velocity from a blower, ambient temperature and solar irradiation. The results showed a decrease of cell temperature by about 7–10 °C with a subsequent increase of electrical efficiency. The cell temperature decreases significantly with the increase of duct height and with the increase of the number and length of fins, the same as in passive cooling. The cell temperature decreases by more than 3 °C at duct height of 0.2 m. The calculated values of cell temperature, open-circuit voltage and short-circuit current of the module with and without active cooling agreed reasonably with the present measured values over the day hours of two successive days in summer season. At air velocity of 1.5 m/s, the increase of electrical efficiency by active cooling was found 0.67–0.80 %. Further increase of air-flow velocity or duct-height in active cooling seeking higher efficiency is not recommended due to increase of consumed electric power by air-blower and limited decrease of cell temperature. This concludes that air cooling is not effective in regions of hot ambient temperatures. For a non-cooled module, the cell temperature is related to the ambient temperature in terms of the solar radiation and NOCT, the datasheet value of normal-operating-cell-temperature. The relationship is modified in the present paper to account for air-flow through the duct seeking its extension for application to air-cooled modules.

Use of benzothiophene ring to improve the photovoltaic efficacy of cyanopyridinone-based organic chromophores: a DFT study.

The benzothiophene based chromophores (A1D1-A1D5) with A-π-A configuration were designed via end-capped tailoring with benzothiophene type acceptors using reference compound (A1R). Quantum chemical calculations were accomplished at M06/6-311G(d,p) level to probe optoelectronic and photophysical properties of designed chromophores. Therefore, frontier molecular orbitals (FMOs), binding energy (Eb), open circuit voltage (Voc), transition density matrix (TDM), density of state (DOS) and UV-Vis analyses of A1R and A1D1-A1D5 were accomplished. The designed compounds (A1D1-A1D5) exhibited absorption values in the visible region as 616.316-649.676 nm and 639.753-665.508 nm in gas and chloroform phase, respectively, comparing with reference chromophore. An efficient charge transference from HOMO towards LUMO was found in A1D1-A1D5 chromophores which was further supported by TDM and DOS analyses. Among all chromophores, A1D2 exhibited unique characteristics such as reduced band gap (2.354 eV), higher softness (σ = 0.424 eV), lower exciton binding energy (0.491 eV) and maximum value of open circuit voltage (Voc = 1.981 V). Consequently, A1D2 may be considered as potential candidate for the development of optoelectronic devices. These analyses revealed that the studied compounds exhibited promising findings. They may be utilized in the realm of organic solar cells.

Exploaration of the influence of end-capped structural modification on photovoltaic properties of selenopheno-thiophene core based non-fullerene chromophores: A DFT study

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.

Boron phosphide (BP) biphenylene and graphenylene networks as anode and anchoring materials for Li/Na-ion and Li/Na–S batteries

Using first-principles density functional theory (DFT) calculations, we evaluate the suitability of BP-biphenylene (b-BP) and BP-graphenylene (g-BP) monolayers for Li+/Na+-ion and Li/Na-S batteries. In our evaluations, we consider factors such as the adsorption energy (Eads) of b-BP and g-BP with adsorbed Li/Na adatoms, Li/Na polysulfides (Li/NaPSs) and S8 clusters as well as the storage capacity and diffusion energy barrier (Ebar) of Li+/Na+-ion on these surfaces. Our results indicate significantly higher Li+/Na+-ion storage capacities for b-BP at 700 mAh/g and g-BP at 550 mAh/g compared to typical graphite anode (372 mAh/g) and other carbon material (450 mAh/g). The Ebar values for Li+/Na+-ion were found to be 0.84/0.63 eV and 0.65/0.37 eV for b-BP and g-BP monolayers, respectively. The obtained Ebar values fall within the acceptable range of theoretically reported value for commercial TiO2 (0.4–1.0 eV) anode. The estimated open-circuit voltage (OCV) values fall within the acceptable range of 0.1–1.0 V for anode materials. Additionally, the Eads values of Li/NaPSs and S8 clusters on b-BP and g-BP surfaces are up to -2.80/-2.91 and -3.00/-3.13 eV, respectively, effectively preventing the unintended decomposition of Li/NaPSs. These findings highlight the potential of both b-BP and g-BP monolayers as promising anode materials for Li/Na-ion batteries as well as anchoring materials for Li/Na–S batteries, mitigating the shuttle effect.

Optical design and bandgap engineering in ultrathin multiple quantum well solar cell featuring photonic nanocavity

AbstractUltrathin solar cells are efficient and captivating devices with unique technological and scientific features in terms of minimal material consumption, fast fabrication processes, and good compatibility with semi‐transparent applications. Such photovoltaic (PV) technologies can enable effective synergy between optical and electronic confinements with large tuning capabilities of all the optoelectronic characteristics. In this work, the implications of the optical design and the bandgap engineering in ultrathin hydrogenated amorphous Si/Ge multiple quantum well (MQW) solar cells featuring photonic nanocavity are analyzed based on experimental measurements and optoelectronic modelling. By changing the period thicknesses and the positions of QWs inside the deep‐subwavelength nanophotonic resonator, the spatial and spectral distributions of the optical field and the local absorption are strongly affected. This leads to a modulation of the absorption resonance condition, the absorption edge and the resulting photocurrent outputs. Because of quantum confinement effect, the change of MQW configurations with different individual QW periods while keeping similar total thickness of about 20 nm alters both the bandgap energy and the band offset at the QW/barrier heterojunctions. This in turn controls the photovoltage as well as the carrier collection efficiency in solar cells. The highest open circuit voltage and fill factor values are achieved by employing MQW device configuration with 2.5 nm‐thin QWs. A record efficiency above 5.5% is reached for such emerging ultrathin Si/Ge MQW solar cell technology using thinner QWs with sufficient number, because of the optimum trade‐off between all the optoelectronic characteristic outputs. The presented design rules for opaque ultrathin solar cells with quantum‐confined nanostructures integrated in a photonic nanocavity can be generalized for the engineering of relevant multifunctional semitransparent PV devices.

Engineering of the Central Core on DBD-Based Materials with Improved Power-Conversion Efficiency by Using the DFT Approach.

Developing proficient organic solar cells with improved optoelectronic properties is still a matter of concern. In the current study, with an aspiration to boost the optoelectronic properties and proficiency of organic solar cells, seven new small-molecule acceptors (Db1-Db7) are presented by altering the central core of the reference molecule (DBD-4F). The optoelectronic aspects of DBD-4F and Db1-Db7 molecules were explored using the density functional theory (DFT) approach, and solvent-state calculations were assessed utilizing TD-SCF simulations. It was noted that improvement in photovoltaic features was achieved by designing these molecules. The results revealed a bathochromic shift in absorption maxima (λmax) of designed molecules reaching up to 776 nm compared to 736 nm of DBD-4F. Similarly, a narrow band gap, low excitation energy, and reduced binding energy were also observed in newly developed molecules in comparison with the pre-existing DBD-4F molecule. Performance improvement can be indicated by the high light-harvesting efficiency (LHE) of designed molecules (ranging from 0.9992 to 0.9996 eV) compared to the reference having a 0.9991 eV LHE. Db4 and Db5 exhibited surprisingly improved open-circuit voltage (V OC) values up to 1.64 and 1.67 eV and a fill factor of 0.9198 and 0.9210, respectively. Consequently, these newly designed molecules can be considered in the future for practical use in manufacturing OSCs with improved optoelectronic and photovoltaic attributes.

Non-linear frequency response analysis for assessment of the ageing history of lithium ion batteries: A combined simulation and experimental approach

In this work, we present a novel approach for identifying the ageing history of lithium-ion batteries based on experimental nonlinear frequency response analysis (NFRA) measurements. A regression model, trained on simulated NFRA data, is shown to be capable of quantifying degradation modes such as solid electrolyte interphase (SEI) growth, lithium plating, and loss of active material (LAM) with no a-priori knowledge of the cell’s historical duty. Our analysis, combining experimental and simulation approaches, demonstrates NFRA’s potential as a powerful tool for ageing diagnosis by capturing various degradation modes. Changes in NFRA response through life exhibit strong correlations with ageing paths, particularly in the frequency range of 0.2 to 10 Hz. Observations highlight a strong influence of the state of charge on the resultant NFRA response, emphasizing that measurements at a single open circuit voltage (OCV) and harmonics values from a single frequency are insufficient for comprehensive characterization. This analysis underscores the need for correlating NFRA at multiple OCVs and frequencies for detailed ageing assessment. Evaluation on commercially relevant cells enhanced the models’ reliability for industrial applications. This quantitative, data-driven approach using NFRA holds potential to enhance battery management strategies, extend lifespan and improve confidence in second-life applications of batteries. Future work should focus on improving regression analysis robustness, reducing dimensionality, and broadening testing conditions.

On the prospects of using B4C3 as a potential electrode material for lithium-ion batteries

Lithium-ion batteries (LIBs) served as promising energy-storage solutions for various applications, from portable electronics to electric-vehicles. There is a growing demand for high-performance electrode materials with improved storage capacity, high cyclic stability, low energy barriers, reduced material toxicity, and cost-effectiveness. This study explores the electrochemical feasibility of B4C3 monolayer as an anode material for LIBs using density functional theory (DFT) computations and molecular dynamic (MD) simulations. The optimum anodic nature of B4C3 is reported based on its structural, electronic, diffusion, storage behaviour, and lithiation studies. The adsorption sites for Li atoms were systematically explored. The lithium saturation requires the adsorption of 29 lithium atoms on B4C3 while preserving stability confirmed by Ab-initio molecular dynamics (AIMD) simulations and ensuring favorable transport characteristics during the lithiation process based on Hirshfeld charge analysis and steric interaction calculations. The storage capacity of the host B4C3 is calculated as 2770.2 mAhg−1 which is notably higher than that of graphite anode. The computed value of open circuit voltage is 0.62 V per Li. The value of diffusion coefficient and ionic conductivity σ is 0.7 × 10−8 m2/s and 0.78 S/m respectively which predicts excellent overall anodic operation of the material. The transition barrier of the Li ions in the material is determined through Cl-NEB, which shows the lowest value of 0.06 eV along the x-axis.

Enhancement of Photo-Electrical Properties of CdS Thin Films: Effect of N2 Purging and N2 Annealing

The impact of N2 purging in the CdS deposition bath and subsequent N2 annealing is examined and contrasted with conventional CdS films, which were deposited without purging and annealed in ambient air. All films were fabricated using the chemical bath deposition method at a temperature of 80 °C on fluorine-doped tin oxide glass slides (FTO). N2 purged films were deposited by introducing nitrogen gas into the deposition bath throughout the CdS deposition process. Subsequently, both N2 purged and un-purged films underwent annealing at temperatures ranging from 100 to 500 °C for one hour, either in a nitrogen or ambient air environment. Photoelectrochemical (PEC) cell studies reveal that films subjected to both N2 purging and N2 annealing exhibit a notable enhancement of 37.5% and 27% in ISC (short-circuit current) and VOC (open-circuit voltage) values, accompanied by a 5% improvement in optical transmittance compared to conventional CdS thin films. The films annealed at 300 °C demonstrate the highest ISC, VOC, and VFB values, 55 μA, 0.475 V, and −675 mV, respectively. The improved optoelectrical properties in both N2-purged and N2-annealed films are attributed to their well-packed structure, enhanced interconnectivity, and a higher sulfur to cadmium ratio of 0.76 in the films.

The influence of selenophene π-linker on photovoltaic properties of pyrrole-4,6(5-H)-dione-based chromophores: A quantum chemical study

A series of 4-H-selenopheno[3,4-c]pyrrole-4,6(5-H)-dione based chromophores (DMSD1-DMSD7) was designed via the introduction of selenophene units (n = 2–7) in the π–spacer of reference compound (DMSR) owing to growing demand of non-fullerene based organic solar cells. The influence of selenophene π–spacer on photovoltaic properties of entitled molecules was explored by utilizing CAM-B3LYP/6-311G (d,p) functional. All the designed compounds were found with lesser values of energy gaps (4.342–3.904 eV) as compared to DMSR (4.764 eV). Similarly, their absorption values were found in the visible region (523.560–533.403 nm) in dichloromethane solvent. Moreover, the entitled chromophores exhibited lower binding energies (1.895–1.566 eV) with higher open circuit voltage values which supported their excellent charge transference properties. The unique properties like least value of bandgap (3.904 eV) with greater charge transfer phenomena were examined for DMSD7 due to the presence of most elongated chain of selenophene-based π–spacer. The density of state and transition density matrix maps illustration further confirmed the efficient charge transfer in DMSD7. Overall, these findings disclosed that by utilizing selenophene π–spacer, photovoltaic properties of organic materials can be efficiently improved.