A (CH 3 NH 3 ) 3 Bi 2 I 9 Perovskite Based on a Two‐Step Deposition Method: Lead‐Free, Highly Stable, and with Enhanced Photovoltaic Performance

Numerical simulation of lead-free vacancy ordered Cs2PtI6 based perovskite solar cell using SCAPS-1D

In recent years, vacancy-ordered halide double perovskites have emerged as promising non-toxic and stable alternatives for their lead-based counterparts in optoelectronic applications. In particular, vacancy ordered Cs2PtI6 has emerged as a star material because of its high absorption coefficient, band gap of 1.37 eV, and long minority carrier lifetime. Despite substantial experimental research on this new class of material, theoretical simulations of their device properties remain scarce. In this work, a novel n-i-p device architecture (FTO/SnO2/Cs2PtI6/MoO3/C) is theoretically investigated using a solar cell capacitance simulator (SCAPS-1D). Theoretical investigations are carried out in order to optimize the device performance structure by varying the perovskite and selective charge transport layer thickness, absorber and interface defect density, operating temperature, back contact, series and shunt resistance, respectively. The optimized device showed an impressive power conversion efficiency (PCE) of 23.52% at 300 K, which is higher than the previously reported values. Subsequent analysis of the device's spectral response indicated that it possessed 98.9% quantum efficiency (QE) and was visibly active. These findings will provide theoretical guidelines for enhancing the performance of Cs2PtI6-based photovoltaic solar cells (PSCs) and pave the way for the widespread implementation of environmentally benign and stable perovskites.

Improved photovoltaic performance of Pb-free AgBi2I7 based photovoltaics

Hybrid perovskites based on bismuth are good candidates for developing lead-free and air-stable photovoltaics, but they have historically been constrained by poor surface morphologies and large band-gap energies. Monovalent silver cations are incorporated into iodobismuthates as part of a novel materials processing method to fabricate improved bismuth-based thin-film photovoltaic absorbers. However, a number of fundamental characteristics prevented them from achieving better efficiency. We examine bismuth iodide perovskite made of silver with improvements in surface morphology and a narrow band gap, and we achieve high power conversion efficiency. AgBi₂I₇ perovskite was used in the fabrication of PSCs as a material for light absorption, and its optoelectronic proficiencies were also studied. We reduced the band gap to 1.89 eV and achieved a maximum power conversion efficiency of 0.96% using the solvent engineering approach. Additionally, simulation studies verified an efficiency of 13.26% by using AgBi₂I₇ as a light absorber perovskite material.

Synthesis of Zn3V2O8/rGO Nanocomposite for Photocatalytic Hydrogen Production

In this study, zinc vanadate/reduced graphene oxide (Zn3V2O8/rGO) composite has been synthesized via a simple approach. Advanced characterization techniques (powder X-ray, scanning electron microscopy, energy dispersive X-ray spectroscopy and ultraviolet-visible (UV-vis) spectroscopy) have been used to authenticate the formation of Zn3V2O8/rGO composite. Subsequently, Zn3V2O8/rGO was applied as photo-catalyst for hydrogen generation using photo-catalysis. The Zn3V2O8/rGO photo-catalyst exhibited a good hydrogen generation amount of 104.6 µmolg−1. The Zn3V2O8/rGO composite also demonstrates excellent cyclic stability which indicated better reusability of the photo-catalyst (Zn3V2O8/rGO). This work proposes a new photo-catalyst for H2 production application. We believe that the presence of synergistic interactions was responsible for the improved photo-catalytic properties of Zn3V2O8/rGO composite. The Zn3V2O8/rGO composite is an environmentally friendly and cost-effective photo-catalyst and can be used for photo-catalytic applications.

Mechanochemical Synthesis of Lead-Free Perovskite-Like MA3 Bi2 I9 for Photo-Catalytic Hydrogen Production

In this study, a highly air stable and eco-friendly methyl ammonium bismuth iodide (MA₃ Bi₂ I₉ ) perovskite-like material has been prepared. After physiochemical characterizations, the synthesized MA₃ Bi₂ I₉ was utilized as photo-catalyst towards hydrogen production. It is important to design and synthesize lead (Pb)-free perovskite-like material (MA₃ Bi₂ I₉ ) for photo-catalytic hydrogen-production applications. The synthesized MA₃ Bi₂ I₉ exhibits excellent photo-catalytic hydrogen generation with a production rate of 11.43 μmolg^-1  h^-1 . In the presence of a platinum co-catalyst, the hydrogen production rate further increases to 172.44 μmolg^-1  h^-1 . The MA₃ Bi₂ I₉ photo-catalyst also demonstrates excellent cyclic stability.

Optimization of Photovoltaic Performance of Pb-Free Perovskite Solar Cells via Numerical Simulation

Recently, the simulation of perovskite solar cells (PSCs) via SCAPS-1D has been widely reported. In this study, we adopted SCAPS-1D as a simulation tool for the numerical simulation of lead-free (Pb-free) PSCs. We used methyl ammonium germanium iodide (MAGeI₃) as a light absorber, zinc oxysulphide (ZnOS) as an electron transport layer (ETL), and spiro-OMeTAD as a hole transport layer. Further, the thickness of the ZnOS, MAGeI₃, and spiro-OMeTAD layers was optimized. The optimal thicknesses of the ZnOS, MAGeI₃, and spiro-OMeTAD layers were found to be 100 nm, 550 nm, and 100 nm, respectively. The optimized MAGeI₃-based PSCs exhibited excellent power conversion efficiency (PCE) of 21.62%, fill factor (FF) of 84.05%, and Jsc of 14.51 mA/cm². A fantastic open circuit voltage of 1.77 V was also obtained using SCAPS-1D. We believe that these theoretically optimized parameters and conditions may help improve the experimental efficiency of MAGeI₃-based PSCs in the future.

Twenty-Two Percent Efficient Pb-Free All-Perovskite Tandem Solar Cells Using SCAPS-1D

Herein, we reported the simulation study of lead (Pb)-free all-perovskite tandem solar cells using SCAPS-1D. Tandem solar cells are comprised of two different cells which are known as the top cell and the bottom cell. We simulated tandem solar cells using methyl ammonium germanium iodide (MAGeI₃) as the top subcell absorber layer due to its wide band gap of 1.9 eV. Further, FA_0.75MA_0.25Sn_0.25Ge_0.5I₃ = FAMASnGeI₃ was used as the bottom subcell absorber layer due to its narrow band gap of 1.4 eV. The tandem solar cells were simulated with MAGeI₃ as the top cell and FAMASnGeI₃ as the bottom subcell using SCAPS-1D. Various electro-transport layers (ETLs) i.e., titanium dioxide, tin oxide, zinc oxide, tungsten trioxide, and zinc selenide, were used to examine the impact of ETL on the efficiency of tandem solar cells. The observations revealed that TiO₂ and ZnSe have more suitable band alignment and better charge-extraction/transfer properties. A reasonably improved efficiency of 23.18% and 22.4% have been achieved for TiO₂ and ZnSe layer-based tandem solar cells, respectively.

Numerical Simulation of NH3(CH2)2NH3MnCl4 Based Pb-Free Perovskite Solar Cells Via SCAPS-1D

Recently, the design and fabrication of lead (Pb)-free perovskite or perovskite-like materials have received great interest for the development of perovskite solar cells (PSCs). Manganese (Mn) is a less toxic element, which may be an alternative to Pb. In this work, we explored the role of NH₃(CH₂)₂NH₃MnCl₄ perovskite as a light absorber layer via SCAPS-1D. A Pb-free PSC device (FTO/TiO₂/NH₃(CH₂)₂NH₃MnCl₄/spiro-OMeTAD/Au) was simulated via SCAPS-1D software. The simulated Pb-free PSCs (FTO/TiO₂/NH₃(CH₂)₂NH₃MnCl₄/spiro-OMeTAD/Au) showed decent power conversion efficiency (PCE) of 20.19%. Further, the impact of the thickness of absorber (NH₃(CH₂)₂NH₃MnCl₄), electron transport (TiO₂), and hole-transport (spiro-OMeTAD) layers were also investigated. Subsequently, various electron transport layers (ETLs) were also introduced to investigate the role of ETL. In further studies, an NH₃(CH₂)₂NH₃MnCl₄-based PSC device (FTO/TiO₂/NH₃(CH₂)₂NH₃MnCl₄/spiro-OMeTAD/Au) was also developed (humidity = ~30-40%). The fabricated PSCs displayed an open circuit voltage (Voc) of 510 mV with a PCE of 0.12%.

Two-Step Synthesis of Bismuth-Based Hybrid Halide Perovskite Thin-Films

Lead halide perovskites have been revolutionary in the last decade in many optoelectronic sectors. Their bismuth-based counterparts have been considered a good alternative thanks to their composition of earth-abundant elements, good chemical stability, and low toxicity. Moreover, their electronic structure is in a quasi-zero-dimensional (0D) configuration, and they have recently been explored for use beyond optoelectronics. A significant limitation in applying thin-film technology is represented by the difficulty of synthesizing compact layers with easily scalable methods. Here, the engineering of a two-step synthesis in an air of methylammonium bismuth iodide compact thin films is reported. The critical steps of the process have been highlighted so that the procedure can be adapted to different substrates and application areas.

Quasi-Zero Dimensional Halide Perovskite Derivates: Synthesis, Status, and Opportunity

In recent decades, many technological advances have been enabled by nanoscale phenomena, giving rise to the field of nanotechnology. In particular, unique optical and electronic phenomena occur on length scales less than 10 nanometres, which enable novel applications. Halide perovskites have been the focus of intense research on their optoelectronic properties and have demonstrated impressive performance in photovoltaic devices and later in other optoelectronic technologies, such as lasers and light-emitting diodes. The most studied crystalline form is the three-dimensional one, but, recently, the exploration of the low-dimensional derivatives has enabled new sub-classes of halide perovskite materials to emerge with distinct properties. In these materials, low-dimensional metal halide structures responsible for the electronic properties are separated and partially insulated from one another by the (typically organic) cations. Confinement occurs on a crystal lattice level, enabling bulk or thin-film materials that retain a degree of low-dimensional character. In particular, quasi-zero dimensional perovskite derivatives are proving to have distinct electronic, absorption, and photoluminescence properties. They are being explored for various technologies beyond photovoltaics (e.g. thermoelectrics, lasing, photodetectors, memristors, capacitors, LEDs). This review brings together the recent literature on these zero-dimensional materials in an interdisciplinary way that can spur applications for these compounds. The synthesis methods, the electrical, optical, and chemical properties, the advances in applications, and the challenges that need to be overcome as candidates for future electronic devices have been covered.

Analysis of Hybrid Hetero-Homo Junction Lead-Free Perovskite Solar Cells by SCAPS Simulator

In this work, we report on the effect of substituting the active intrinsic i-layer on a conventional pin structure of lead-free perovskite solar cell (PSC) by a homo p-n junction, keeping the thickness of the active layer constant. It is expected that when the active i-layer is substituted by a p-n homo junction, one can increase the collection efficiency of the photo-generated electrons and holes due to the built-in electric field of the homo junction. The impact of the technological and physical device parameters on the performance parameters of the solar cell have been worked out. It was found that p-side thickness must be wider than the n-side, while its acceptor concentration should be slightly lower than the donor concentration of the n-side to achieve maximum efficiency. In addition, different absorber types, namely, i-absorber, n-absorber and p-absorber, are compared to the proposed pn-absorber, showing a performance-boosting effect when using the latter. Moreover, the proposed structure is made without a hole transport layer (HTL) to avoid the organic issues of the HTL materials. The back metal work function, bulk trap density and ETL material are optimized for best performance of the HTL-free structure, giving Jsc = 26.48, Voc = 0.948 V, FF = 77.20 and PCE = 19.37% for AM1.5 solar spectra. Such results highlight the prospective of the proposed structure and emphasize the importance of using HTL-free solar cells without deteriorating the efficiency. The solar cell is investigated by using SCAPS simulator.

A Potential Checkmate to Lead: Bismuth in Organometal Halide Perovskites, Structure, Properties, and Applications

The remarkable optoelectronic properties and considerable performance of the organo lead-halide perovskites (PVKs) in various optoelectronic applications grasp tremendous scientific attention. However, the existence of the toxic lead in these compounds is threatening human health and remains a major concern in the way of their commercialization. To address this issue, numerous nontoxic alternatives have been reported. Among these alternatives, bismuth-based PVKs have emerged as a promising substitute because of similar optoelectronic properties and extended environmental stability. This work communicates briefly about the possible lead-alternatives and explores bismuth-based perovskites comprehensively, in terms of their structures, optoelectronic properties, and applications. A brief description of lead-toxification is provided and the possible Pb-alternatives from the periodic table are scrutinized. Then, the classification and crystal structures of various Bi-based perovskites are elaborated on. Detailed optoelectronic properties of Bi-based perovskites are also described and their optoelectronic applications are abridged. The overall photovoltaic applications along with device characteristics (i.e., V OC, J SC, fill factor, FF, and power conversion efficiency, PCE), fabrication method, device architecture, and operational stability are also summarized. Finally, a conclusion is drawn where a brief outlook highlights the challenges that hamper the future progress of Bi-based optoelectronic devices and suggestions for future directions are provided.

Co-evaporation as an optimal technique towards compact methylammonium bismuth iodide layers

The most studied perovskite-based solar cells reported up to date contain the toxic lead in its composition. Photovoltaic research and development towards non-toxic, lead-free perovskite solar cells are critical to finding alternatives to reduce human health concerns associated with them. Bismuth-based perovskite variants, especially in the form of methylammonium bismuth iodide (MBI), is a good candidate for the non-toxic light absorber. However, the reported perovskite variant MBI thin films prepared by the solution process so far suffers from poor morphology and surface coverage. In this work, we investigate for the first time the optoelectronic, crystallographic and morphological properties of MBI thin films prepared via thermal co-evaporation of MAI and BiI₃. We find by modifying the precursor ratio that the layer with pure MBI composition lead to uniform, compact and homogeneous layers, broadening the options of deposition techniques for lead-free based perovskite solar cells.

Lead-Free Perovskites for Lighting and Lasing Applications: A Minireview

Research on materials with perovskite crystal symmetry for photonics applications represent a rapidly growing area of the photonics development due to their unique optical and electrical properties. Among them are high charge carrier mobility, high photoluminescence quantum yield, and high extinction coefficients, which can be tuned through all visible range by a controllable change in chemical composition. To date, most of such materials contain lead atoms, which is one of the obstacles for their large-scale implementation. This disadvantage can be overcome via the substitution of lead with less toxic chemical elements, such as Sn, Bi, Yb, etc., and their mixtures. Herein, we summarized the scientific works from 2016 related to the lead-free perovskite materials with stress on the lasing and lighting applications. The synthetic approaches, chemical composition, and morphology of materials, together with the optimal device configurations depending on the material parameters are summarized with a focus on future challenges.