Photovoltaic Applications Research Articles

Spin-coated Cu2nisns4 Thin Films: The Impact Of Thiourea's Molar Concentration

Copper-Nickel-Tin-Sulfide, Cu2NiSnS4 (CNTS) thin films are deposited on to glass substrates through simple and cost-effective spin coating technique, with the variations in the molar concentration of thiourea (MCT). In this research, CuCl2.2H2O, NiCl2.6H2O, SnCl2.2H2O and SC(NH2)2 are utilized as the sources of copper, nickel, tin, and sulfur ions, respectively. The influence of MCT on the structural, morphological, and optical properties of the CNTS thin films have been investigated. The XRD results reveal that all CNTS thin films exhibit a cubic crystalline structure and a preferential orientation along the (111) plane. The mean crystallite size for the intense peak (111) is found to enhance from 7.24 to 10.81 nm with MCT. Conversely, the dislocation density and microstrain are found to decrease from to and to , respectively. The density and surface roughness of the films are also found to increase with MCT. The absorption coefficient (on the order of ), refractive index, extinction coefficient, dielectric constant, and optical conductivity all increased, while the percentage transmittance and optical band gap decreased with MCT. These outcomes suggest that CNTS thin film could a promising material for the use as an absorbing layer in photovoltaic applications and optoelectronic devices. Bangladesh Journal of Physics, 28(1), 39-50, June 2021

Thermal Annealing Effect on Properties of Nickel Oxide (NiO) Thin Films for Photovoltaic Applications

In this study, the impact of annealing temperature (TA) from room temperature (RT) to 400 °C on the structural, optical and electrical properties of NiO thin films deposited using sol‐ gel spin coating technique on glass substrate is presented. A theoretical approach is also employed to calculate the open circuit voltage (VOC) from the energy band gap (Eg) value, fill factor (FF), short circuit current (ISC), and power conversion efficiency (PCE) of the material for solar cell applications. Crystallinity improvement is observed upon annealing the NiO thin films and the average size of crystallites varies from 28 to 34 nm with a maximum value observed for 300 °C annealed film. The SEM micrographs confirm the nano form of NiO nanoparticles, with particles that are between 73 and 100 nm in size. All the films are semitransparent with transmittance >55% and the thin film annealed at 300 °C exhibited 88% transmittance in the visible region, making it a promising option as a transparent conducting oxide (TCO) in photovoltaic applications. The I–V curves display a non‐linear behaviour for all annealing temperatures. The conductivity increases with an increase in TA and the film annealed at 300 °C shows the highest conductivity.

Surface Template Realizing Oriented Perovskites for Highly Efficient Solar Cells.

Formamidinium lead iodide (FAPbI3) perovskite films, ensuring optically active phase purity with uniform crystal orientation, are ideal for photovoltaic applications. However, the optically active α-FAPbI3 phase is easy to degrade into δ-phase due to numerous defects within randomly oriented films. Here, a "quasi-2D" perovskite template is pre-deposited on the film surface within the crystallization process based on the two-step preparation technology, which directly induced pure and highly orientated crystallization of α-FAPbI3 across the downward growth process. Furthermore, the enlarged interaction between 2D components with colloidal properties and lead iodide delayed the crystallization process effectively, yielding high crystallinity with low trap state density. The resulting perovskite photovoltaic devices exhibited a champion efficiency as high as 25.79% with comprehensively improved device stability. This work provides new insights into the utilization of 2D components and the formation mechanism behind 2D perovskites.

Decoding circular dichroism Contributions in Chiral Hybrid Perovskites

Hybrid organic–inorganic perovskites (HOIPs) are promising materials in optoelectronics, particularly for photovoltaic applications, due to their tunable properties and ease of fabrication. Among them, chiral HOIPs are gaining attention for their unique chiroptical properties, by the incorporation of chiral organic molecules into their structure. Despite their potential, the relationship between chiral HOIP structures and their chiroptical properties, such as circular dichroism (CD) spectra, remains challenging to decrypt. This study introduces a simulation workflow based on Density Functional Theory (DFT) and Time‐Dependent DFT (TD‐DFT) to model the CD spectrum of the chiral 2D perovskite encapsulating S‐ 1‐(3‐bromophenyl)‐ethylamine (S‐(3Br‐MBA)2PbI4). The approach combines ab‐initio molecular dynamics (AIMD) with TD‐DFT calculations evaluating the contributions on the whole chiral hybrid perovskite scaffold and those of the isolated ligands, allowing us to dissect the contributions to the CD spectrum of chiral ligands and of the metal‐halide sublattice. Additionally, the absorption dissymmetry factor gabs​ has been also computed finding good agreement with the experimental value. This work provides valuable insights for the design of advanced chiroptoelectronic materials.

Tuning the Electronic and Optical Properties of Crystalline Anthracene by Doping and Pressure for Photovoltaic Applications

Tuning the Electronic and Optical Properties of Crystalline Anthracene by Doping and Pressure for Photovoltaic Applications

A dozen predicted SiGe alloys with low enthalpies and strong absorption of sunlight for photovoltaic applications.

Silicon germanium alloy materials have promising potential applications in the optoelectronic and photovoltaic industries due to their good electronic properties. However, due to the inherent brittleness of semiconductor materials, they are prone to rupturing under harsh working environments, such as high stress or high temperature. Here, we conducted a systematic search for silicon germanium alloy structures using a random sampling strategy, in combination with group theory and graph theory (RG2), and 12 stable SiGe structures in 2-8 stacking orders were predicted. All 12 stable SiGe crystals exhibit a popular bandwidth of 1.06-1.19 eV, approaching the optimal Shockley Queisser limit (≈1.4 eV). Among these, 6 structures showed quasi-direct band gaps. Considering their potential photovoltaic applications, we systematically studied the changes in their enthalpy, stability, mechanical stability (elastic moduli), lattice parameters, band structures, and light absorption under a stress load of up to 20 GPa. These new SiGe crystals featured relatively low enthalpies (even as low as 0.009 eV per atom), and good stability and mechanical properties. In addition, the absorption spectra of these materials demonstrated a high absorption intensity for the solar spectrum that was approximately 3 times higher than that of conventional diamond silicon, even under a 20 GPa stress. The present study uses the predicted 2-8H SiGe to provide new insights into the photovoltaic applications of SiGe alloy structures.

Exploring the Optoelectronic Properties and Solar Cell Performance of Cs2SnI6−xBrx Lead-Free Double Perovskites: Combined DFT and SCAPS Simulation

This paper presents detailed results regarding the physical behavior of Cs2SnI6−xBrx alloys for their potential use in photovoltaic applications. Numerical computations based on density functional theory (DFT) revealed that Br substitution at I sites significantly influenced the electronic structure of Cs2SnI6, resulting in an increase in bandgap values from 1.33 eV to 2.24 eV. Additionally, we analyzed the optical properties, including the absorption coefficient, which exhibited high values in the visible light region, highlighting the material’s excellent light-trapping abilities. Moreover, Cs2SnI6−xBrx compounds were employed as absorber materials in an fluorine-doped tin oxide (FTO) TiO2/Cs2SnI6/P3HT/Ag perovskite solar cell (PSC) to investigate its performance. The simulation process consisted of two interconnected steps: (i) the DFT calculations to derive the material properties and (ii) the SCAPS–1D (one-dimensional (1D) solar cell capacity simulator) simulation to model device performance. To ensure reliability, the SCAPS–1D simulation was calibrated against experimental data. Following this, Cs2SnI6−xBrx compound with various ratios of Br content, ranging from 0 to 6, was investigated to propose an efficient solar cell design. Furthermore, the cell structure was optimized, resulting in a development in the power conversion efficiency (PCE) from 0.47% to 3.07%.

Unveiling the potential of lead-free KInBr3 and RbInBr3 perovskites: a breakthrough in optoelectronic and photovoltaic performance through DFT (HSE hybrid functional) and SCAPS-1D simulations

ABSTRACT Lead-free halide perovskites are emerging as promising materials for solar cells due to their exceptional properties. KInBr₃ and RbInBr₃ are particularly notable, showing great potential for lead-free perovskite solar cells (PSCs). Using density functional theory (DFT) with the VASP framework, we investigated their structural, electronic, and optical properties. Both materials exhibit direct band gaps, with 0.93 eV for KInBr₃ and 0.77 eV for RbInBr₃, calculated using the hybrid HSE functional. The density of states (DOS) analysis reveals that the In s/p orbitals dominate the band edges, making these materials suitable for photovoltaic applications. Optical studies confirm strong light absorption in the visible and ultraviolet regions. Furthermore, SCAPS-1D simulations for a solar cell with the structure Ag/MoO₃/KInBr₃/ZnO/ITO yielded a power conversion efficiency (PCE) of 30.25%, demonstrating the exceptional potential of KInBr₃ for high-performance solar energy technologies.

Long-Range Charge Transport Facilitated by Electron Delocalization in MoS2 and Carbon Nanotube Heterostructures.

Controlling charge transport at the interfaces of nanostructures is crucial for their successful use in optoelectronic and solar energy applications. Mixed-dimensional heterostructures based on single-walled carbon nanotubes (SWCNTs) and transition metal dichalcogenides (TMDCs) have demonstrated exceptionally long-lived charge-separated states. However, the factors that control the charge transport at these interfaces remain unclear. In this study, we directly image charge transport at the interfaces of single- and multilayered MoS2 and (6,5) SWCNT heterostructures using transient absorption microscopy. We find that charge recombination becomes slower as the layer thickness of MoS2 increases. This behavior can be explained by electron delocalization in multilayers and reduced orbital overlap with the SWCNTs, as suggested by nonadiabatic (NA) molecular dynamics (MD) simulations. Dipolar repulsion of interfacial excitons results in rapid density-dependent transport within the first 100 ps. Stronger repulsion and longer-range charge transport are observed in heterostructures with thicker MoS2 layers, driven by electron delocalization and larger interfacial dipole moments. These findings are consistent with the results from NAMD simulations. Our results suggest that heterostructures with multilayer MoS2 can facilitate long-lived charge separation and transport, which is promising for applications in photovoltaics and photocatalysis.

MXene-based multilayered and ultrawideband absorber for solar cell and photovoltaic applications

We proposed the ultrawideband solar absorber using the multisized metal resonator oriented on the top of the multilayered Metal-SiO₂-MXene-MgF₂-Tungsten structure. We have carried out a numerical investigation of this structure for the 100–2500 THz frequency, which covers the infrared, visible, and UV spectra. The proposed solar absorber is numerically investigated for the different physical parameters, such as the height of the layers, unit cell size, and resonator orientation, to identify optimized results for the high absorption capacity. The structure presented in the study shows promise, with an average absorption of 80% over the large frequency spectrum of 100–2500 THz. This structure was also investigated for the variation in oblique incident angle, which showcases the absorption stability up to 60⁰ of the incident angle. We have also reported the comparative analysis for this proposed absorber structure with other designs, demonstrating the absorption efficiency over infrared, visible, and UV spectra. The proposed structure and discrete resonator length can offer a better solution for trapping the different frequency ranges, resulting in high absorption over a wideband frequency. This study can be applied to designing highly efficient parasitic solar absorber structures, which are essential to highly efficient photovoltaic and solar cell design.

First-Principles Study of Anionic Diffusion in Two-Dimensional Lead Halide Perovskite Lateral Heterostructures.

Perovskite heterostructures have attracted wide interest for their photovoltaic and optoelectronic applications. The interdiffusion of halide anions leads to the poor stability and shorter lifetime of the halide perovskite heterostructures. Covering organic cations on the surface of perovskite heterostructures, the diffusion of ions can effectively be suppressed. However, the migration mechanism on two-dimensional lead halide perovskite lateral heterostructures under different organic cations remains inadequately explored. In this work, we performed first-principles calculations on the ion migration in two-dimensional (2D) lead halide perovskite lateral heterostructures with different interface defects and different cations. We found that the migration of iodine atoms across the interface in the heterostructures is more preferable than that of bromine atoms, regardless of the cations. Meanwhile, the migration of iodine atoms from the in-plane to the out-plane direction has the lowest energy barrier compared to other directions. Our calculations also reveal that both the type of cation and the migration path selected affect the energy barrier for anion migration, exhibiting either inhibitory or promoting effects. Specifically, the organic cation 345FAn, an ammonium ligand, showed an excellent promoting effect on the anion migration, while the BA cation exhibited an inhibiting effect. The calculated interdiffusion rate includes the interfacial single bromine vacancy, which is consistent with previous experimental observations. However, the heterostructures with interfacial single iodine defects exhibit a higher interdiffusion rate. Our findings on the ion migration mechanism in lead halide perovskite lateral heterostructures contribute to both experimental discussions and theoretical insights.

Modification of the Se/MoOx Rear Interface for Efficient Wide-Band-Gap Trigonal Selenium Solar Cells.

Trigonal selenium (t-Se) is a promising wide-band-gap photovoltaic material with a high absorption coefficient, abundant resources, simple composition, nontoxicity, and a low melting point, making it suitable for absorbers in advanced indoor and tandem photovoltaic applications. However, severe electrical losses at the rear interface of the t-Se absorber, caused by work function and lattice mismatches, limit the voltage output and overall performance. In this study, a strategy to enhance carrier transport and collection by modifying interfacial chemical interactions is proposed. By applying a controlled heat process during the deposition of the MoOx hole transport layer, a chemical interaction at the t-Se/MoOx interface can be facilitated. This results in the formation of an interfacial MoSex layer, leading to improved valence band alignment and reduced barrier and recombination losses. As a result, the performance of t-Se thin-film solar cells is improved compared to those without the heating process.

Roadmap for Designing Donor-π-Acceptor Fluorophores in UV-Vis and NIR Regions: Synthesis, Optical Properties and Applications.

Donor acceptor (D-π-A) fluorophores containing a donor unit and an acceptor moiety at each end connected by a conjugated linker gained attention in the last decade due to their conjugated system and ease of tunability. These features make them good candidates for various applications such as bioimaging, photovoltaic devices and nonlinear optical materials. Upon excitation of the D-π-A fluorophore, intramolecular charge transfer (ICT) occurs, and it polarizes the molecule resulting in the 'push-pull' system. The emission wavelengths of fluorophores can be altered from UV-vis to NIR region by modifying the donor unit, acceptor moiety and the π linker between them. The NIR emitting fluorophores with restricted molecular rotations are used in aggregation-induced emission (AIE). D-π-A fluorophores with carboxylic acid and cyano groups are preferred in photovoltaic applications, and fluorophores with large surface area are used for two photon absorbing applications. Herein, we report the synthesis, optical properties, and applications of various D-π-A fluorophores in UV-vis and NIR region.

Electronic properties of MAPbxSn1−xI3 hybrid perovskite alloys: k.p modeling for tetragonal crystal symmetry with C4v point group

MAPb x Sn 1 − x I 3 alloys are highly promising for photovoltaic, optoelectronic, and spintronics applications. Using k.p calculations, we derived the fundamental band parameters of these tetragonal hybrid halide perovskites as a function of Pb content (x). Our study focuses on the experimentally confirmed C4v point group structures: P4mm for Sn-rich alloys and I4cm for Pb-rich alloys. Our theoretical model successfully reproduces the non-monotonic behavior of the bandgap and provides detailed insights into the electron, hole, and reduced exciton masses (me, mh, and μ). We find that hole masses are slightly larger than electron masses, with both increasing linearly as x rises. At the structural transition (x=0.5) between P4mm and I4cm, we observe a discontinuity in hole masses and a steeper linear increase in Pb-rich structures. The calculated exciton masses show excellent agreement with experimental data across a wide range of alloy compositions. Additionally, we predict the Landé g-factors for charge carriers (ge, gh) and excitons (gX). For Pb-rich alloys, ge increases with decreasing bandgap energy, while for Sn-rich alloys, ge decreases. Exciton g-factors gX are predominantly governed by the large positive ge values, as the smaller negative gh values provide minimal compensation. Consequently, gX is not constant but varies with the bandgap, ranging from 2.4 and 4.8 for Pb-rich alloys and from 4.8 and 3.7 for Sn-rich alloys. These results highlight the tunable electronic and spin properties of MAPbxSn1−xI3 alloys, positioning them as versatile candidates for next-generation device applications.

High-Specific Power Flexible Photovoltaics from Large-Area MoS2 for Space Applications.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) such as MoS2 and WSe2 are excellent candidates for photovoltaic (PV) applications. Here, we present the modeling, fabrication, and characterization of large-area CVD-grown MoS2-based flexible PV on an off-the-shelf, 3 μm-thick flexible colorless polyimide with polyimide encapsulation designed for space structures. The devices are characterized under 1 sun AM0 illumination and show a V OC of 0.180 V and a specific power of 0.001 kW/kg for a subnanometer-thick, single MoS2 monolayer absorber. Model projections indicate that the polyimide encapsulant introduces negligible absorption loss, and up to 12.97 kW/kg specific power is attainable for a 100 nm-thick MoS2 absorber layer. The devices maintain their performance after repetitive bending down to 5 mm bend radius. An increase in performance is measured after radiation exposure to 1 MeV e- fluence, which is partially attributed to defect healing. Techno-economic analysis shows that even with a lower efficiency, the specific power of a 2D PV array designed for a 6U CubeSat is 2 orders of magnitude higher, and the cost to deploy in space is 2 orders of magnitude less than that of a Si panel used in space. This indicates that the 2D TMDC-based PV has great potential for space applications.

A new configuration of DC-DC converter with increased voltage gain for photovoltaic application

ABSTRACT The output voltage in photovoltaic solar panels is usually low. Therefore, DC-DC step-up converters are employed in these systems to increase the voltage level. A new topology with interleaved non-isolated high gain is suggested for photovoltaic application in the present paper where a combination of two voltage multipliers was used to increase the voltage gain. Employing the interleaved technique reduced the input current ripple. The voltage stress is significantly reduced across the semiconductor components, making it possible for the converter to use high-performance components, and therefore reducing conduction losses. Analysis was performed, and comparisons are presented among the proposed converter and seven similar converters. A 170-watt laboratory prototype with 12.5 V input and 170 V output voltages was fabricated for experimental assessment of the converter’s performance. Finally, experimental results were analysed and compared with analytical results.

Damp‐Heat–Induced Degradation of Lightweight Silicon Heterojunction Solar Modules With Different Transparent Conductive Oxide Layers

ABSTRACTLightweight photovoltaic applications are essential for diversifying the solar energy supply. This opens up vast new scenarios for solar modules and significantly boosts the capacity of renewable energy. To ensure high efficiency and stability of the solar modules, several challenges need to be overcome. Degradation due to elevated temperature and/or humidity is a critical concern for silicon heterojunction (SHJ) solar modules. Here, we investigated the stability and degradation mechanism of encapsulated cells with lightweight configurations where the cells are based on three different types of transparent‐conductive oxide (TCO): indium tin oxide (ITO), aluminum‐doped zinc oxide (AZO), and a combination of ITO/AZO/ITO under humid and thermal environmental conditions. A damp heat (DH) test at a temperature of 85°C and relative humidity (RH) of 85% was performed on lightweight modules for 1000 h. Our results show that AZO is the most susceptible to DH degradation. The AZO film was damaged by the combined effects of moisture ingress and delamination of the interconnection foil, resulting in a decrease in the conductivity of the AZO film, leading to a dramatic increase in Rs and a decrease in FF of the modules. Consequently, moisture has a greater chance of percolating through the damaged AZO layer into the a‐Si:H passivation layer, causing passivation degradation, which leads to an increase in recombination, resulting in a decrease in Voc of the modules. In particular, after capping the AZO film with an ITO film, the efficiency loss of the ITO/AZO/ITO module was significantly reduced. This suggests that the ITO film could be a promising protective capping layer for the AZO‐based solar cells.

Machine Learning Assisted Bithiophene Based Donor Acceptor Selection to Design New Fluoresent Dyes for Photovoltaic Applications.

This study investigates the electronic properties and photovoltaic (PV) performance of newly designed bithiophene-based dyes, focusing on their light harvesting efficiency (LHE), open-circuit voltage (Voc), fill factor (FF), and short-circuit current density (Jsc).These new dyes are designed with the help of machine learning (ML) to design best donor acceptor designs. For this, we collect 2567 differenr electron donor groups and calculated their bandgap with the help of Random Forest (RF) Regression method. Their maximum absorption (λmax) values are redshifted with their 367-501nm range having TA1 with higher value. Their LHE values range from 52 to 89%, with TA3 demonstrating the highest efficiency. Their Voc values varies significantly, with TA2 achieving the highest at 1.584V, while TA5 and TA6 exhibit lowest values. Their FF)from 25.9 for TA4 to 59.3 for TA3, highlighting the superior charge extraction capabilities. Their Jsc values further reflect their performance potential, with TA1 leading at 39.43mA/cm², while TA4 and TA6 show significantly lower values of 3.28 and 4.40mA/cm², respectively. Overall, the findings suggest that the bithiophene-based dyes, particularly TA2 and TA3, possess promising characteristics for enhancing the efficiency of solar cells.

Quotient Complex (QC)-Based Machine Learning for 2D Hybrid Perovskite Design.

With remarkable stability and exceptional optoelectronic properties, two-dimensional (2D) halide layered perovskites hold immense promise for revolutionizing photovoltaic technology. Effective data representations are key to the success of all learning models. Currently, the lack of comprehensive and accurate material representations has hindered AI-based design and discovery of 2D perovskites, limiting their potential for advanced photovoltaic applications. In this context, this work introduces a novel computational topology framework termed the quotient complex (QC), which serves as the foundation for the material representation. The proposed QC-based features are seamlessly integrated with learning models for the advancement of 2D perovskite design. At the heart of this framework lies the quotient complex descriptors (QCDs), representing a quotient variation of simplicial complexes derived from materials' unit cell and periodic boundary conditions. Differing from prior material representations, this approach encodes higher-order interactions and periodicity information simultaneously. Based on the well-established new materials for solar energetics (NMSE) databank, the proposed QC-based machine learning models exhibit superior performance against all existing counterparts. This underscores the paramount role of periodicity information in predicting material functionality, while also showcasing the remarkable efficiency of the QC-based model in characterizing materials' structural attributes.

Ultrafast Dynamics of Diketopyrrolopyrrole Dimers.

Diketopyrrolopyrroles (DPPs) have attracted attention for their potential applications in organic photovoltaics due to their tunable optical properties and charge-carrier mobilities. In this study, we investigate the excited-state dynamics of a DPP dimer using time-dependent density functional theory (TDDFT) and nonadiabatic molecular dynamics simulations. Our results reveal a near-barrierless hydrogen migration state intersection that facilitates ultrafast internal conversion with a lifetime of about 400 fs, leading to fluorescence quenching. Electronic density analysis along the relaxation pathway confirms a hydrogen atom transfer mechanism. These findings highlight the critical role of state intersections in the photophysical properties of DPP dimers, providing new insights for the design of functionalized DPP systems aimed at suppressing nonradiative decay for enhanced performance in photovoltaic applications.