Lead-free Perovskite Solar Cells Research Articles

Hole Transport Materials for Tin-Based Perovskite Solar Cells: Properties, Progress, Prospects.

The power conversion efficiency of modern perovskite solar cells has surpassed that of commercial photovoltaic technology, showing great potential for commercial applications. However, the current high-performance perovskite solar cells all contain toxic lead elements, blocking their progress toward industrialization. Lead-free tin-based perovskite solar cells have attracted tremendous research interest, and more than 14% power conversion efficiency has been achieved. In tin-based perovskite, Sn2+ is easily oxidized to Sn4+ in air. During this process, two additional electrons are introduced to form a heavy p-type doping perovskite layer, necessitating the production of hole transport materials different from that of lead-based perovskite devices or organic solar cells. In this review, for the first time, we summarize the hole transport materials used in the development of tin-based perovskite solar cells, describe the impact of different hole transport materials on the performance of tin-based perovskite solar cell devices, and summarize the recent progress of hole transport materials. Lastly, the development direction of lead-free tin-based perovskite devices in terms of hole transport materials is discussed based on their current development status. This comprehensive review contributes to the development of efficient, stable, and environmentally friendly tin-based perovskite devices and provides guidance for the hole transport layer material design.

Engineering Stable Lead-Free Tin Halide Perovskite Solar Cells: Lessons from Materials Chemistry.

Substituting toxic lead with tin (Sn) in perovskite solar cells (PSCs) is the most promising route toward the development of high-efficiency lead-free devices. Despite the encouraging efficiencies of Sn-PSCs, they are still yet to surpass 15% and suffer detrimental oxidation of Sn(II) to Sn(IV). Since their first application in 2014, investigations into the properties of Sn-PSCs have contributed to a growing understanding of the mechanisms, both detrimental and complementary to their stability. This review summarizes the evolution of Sn-PSCs, including early developments to the latest state-of-the-art approaches benefitting the stability of devices. The degradation pathways associated with Sn-PSCs are first outlined, followed by describing how composition engineering (A, B site modifications), additive engineering (oxidation prevention), and interface engineering (passivation strategies) can be employed as different avenues to improve the stability of devices. The knowledge about these properties is also not limited to PSCs and also applicable to other types of devices now employing Sn-based perovskite absorber layers. A detailed analysis of the properties and materials chemistry reveals a clear set of design rules for the development of stable Sn-PSCs. Applying the design strategies highlighted in this review will be essential to further improve both the efficiency and stability of Sn-PSCs.

Performance assessment of sustainable highly efficient CsSn0.5Ge0.5I3/FASnI3 based Perovskite Solar Cell: A numerical modelling approach

Lead-free perovskite solar cells (PVSC) are emerging as a very relevant research topic in the modern environment era, where toxicity and stability are the two most significant hurdles for lead-based PVSC design. Existing lead-free perovskites suffer from the same inefficiency problems. The focus of this research is the development and analysis via SCAPS-1D simulator of Pb-free design of CsSn0.5Ge0.5I3/FASnI3 based PVSC. A numerical modelling programming tool is used to examine the influence of many critical parameters on device efficacy. These parameters include the decision of the optimal hole transport layer (HTL), optimal electron transport layer (ETL), doping density, the optimized thickness of both absorber layers, defect density, and interface defect density between numerous films. The highest power conversion efficiency (PCE) of 31.58%, short circuit current density (Jsc) of 29.239 mA/cm2, open-circuit voltage (Voc) of 1.202 V, and fill factor (FF) of 89.55% are all achieved by the optimized device architecture with MoS2 as the HTL and IGZO as the ETL. This demonstrates that high-performance lead-free PVSC can be achieved experimentally by further optimization of the device characteristics.

Effect of surface termination on electronic and optical properties of lead-free tin-based eco-friendly perovskite solar cell: a first principal study.

The lead (Pb)-based halide perovskites have been reported to be promising materials for photovoltaic applications; however, the presence of toxic lead in them concerns the environmental and health issues. In this work, we have, therefore, studied the lead-free and non-toxic tin-based halide perovskite, CsSnI3, which is an eco-friendly material with high power conversion efficiency, thus, being a potential candidate for photovoltaic applications. We have investigated the influence of CsI and SnI2-terminated (001) surfaces on structural, electronic and optical properties of lead-free tin-based halide perovskite CsSnI3 from the first principal calculations, based on density functional theory (DFT). The calculations of electronic and optical parameters are performed under the parameterisation of PBE_Sol for exchange-correlation functions conjugated with modified- Beche-Johnshon (mBJ) exchange potential. The optimised lattice constant, the energy band structure and the density of states (DOS) have been calculated for the bulk and different terminated surface structures. The optical properties of CsSnI3 are computed in terms of the real and imaginary part of absorption coefficient, dielectric function, refractive index, conductivity, reflectivity, extinction coefficient and electron energy loss. The photovoltaic characteristics for the CsI-termination are found to be better than the bulk and SnI2-terminated surfaces. This study reveals that optical and electronic properties can be tuned by selecting proper surface termination in halide perovskite CsSnI3. The CsSnI3 surfaces exhibit semiconductor behaviour with a direct energy band gap and a high value of absorption power in the ultraviolet and visible region, rendering these inorganic halide perovskite materials important for the eco-friendly and efficient optoelectronic devices.

Optimal design and performance assessment of CH3NH3SnBr3 lead-free perovskite solar cells for > 24% efficiency

Optimal design and performance assessment of CH3NH3SnBr3 lead-free perovskite solar cells for > 24% efficiency

A simulation study of all inorganic lead-free CsSnBr3 tin halide perovskite solar cell

Perovskite solar cells (PSCs) have achieved champion efficiency from 3.8% to 25.2% in a decade. The major issues associated with perovskite solar cells are stability and toxicity. These PSCs quickly degrade in the ambient environment. The use of toxic lead in the hybrid organic–inorganic solar cells makes them unsafe as future technology. Recently, tin-based perovskite solar cells have gained attention as an alternative for resolving the issues of stability and toxicity. Numerical simulations help in finding the possible alternatives and understanding the underlying mechanism to solve the toxicity and stability problem. The present work aims to simulate lead-free perovskite solar cells and optimise the width of each layer. SCAPS_1D simulation software is used here to conduct the study. CsSnBr3 is used as an absorber layer, while SnO2 is used as an electron transport layer, and CuI is used as a hole transport layer. The simulation is conducted at 300 K temperature and AM1.5G solar spectrum. The device achieves a remarkable photovoltaic conversion efficiency of 17.06%, an open-circuit voltage (Voc) of 1.19 V, a current density of 16.94 mA/cm2, and a fill factor of 84.19%. Thus, tin-based halide perovskite paves the way for future environmentally friendly and stable perovskite solar cells.

Development of environmental friendly high performance Cs2TiBr6 based perovskite solar cell using numerical simulation

The stability and toxicity problems pose a significant obstacle to the practical application of lead-based perovskite solar cells. Ti-based all-inorganic perovskite solar cells (PSCs) may be essential for the marketing of elevated PSCs under such conditions. This study investigates the theoretical viability of a Cs2TiBr6-based PSC that is efficient, lead-free, and environmentally benign. The evaluation of several electron transport layers (ETLs) and hole transport layers (HTLs) is done in an attempt to choose materials that would provide more stable and efficient PSCs. The emergence of novel Au/CuSbS2/Cs2TiBr6/CdS/TCO configurations is a direct result of investigating factors such as charge transport materials and their thickness, electron transport materials, absorber thickness, absorber defect density, TCO and its thickness, back metal contacts, series resistance, and shunt resistance. SCAPS-1D software is employed to optimize and analyze each composite layer in order to enable enhanced performance. An optimization results in a maximum power-conversion efficiency of 23.77% for the suggested PSC. The achieved outcomes confirmed that Cs2TiBr6 can contribute significantly to the development of the highly effective lead-free all-inorganic perovskite solar cell technology.

Numerical investigation of toxic free perovskite solar cells for achieving high efficiency

Increasing efficiency, simple and inexpensive fabrication process and flexibility nature of organic metal halide perovskite (PVK) based solar cell has fascinated the researchers around the globe. However, Lead, a poisonous substance in PVK solar cell causes various issues which directly or indirectly impact the environment as well as the health of living things. It prevents the commercialization of PVK based solar cell. To overcome this, a number of lead-free perovskite solar cell has been designed and fabricated. But the conversion efficiency is still not up to par because of intrinsic losses. In order to improve the efficiency, a thorough theoretical investigation is required that can reveal the cause behind these losses. In this study a special PVK material named methylammonium tin iodide (MASnI3) is used in simulation platform to design a highly efficient organic lead-free solar cell. This study focuses on the optimization of active layer thickness, working temperature, capacitance-voltage (C-V), and impedance and defect density, as they plays major roles in determining the performance of toxic free organic PVK solar cell. The study confirms an high efficiency (η) of 24.22% at the optimized condition. Such high efficiency with an optimized structure can open a door for the commercialization of lead free PVK based solar cell.

Optimizing the Performance of Lead-free CH3NH3SnI3 Perovskite Solar Cells via Thickness, Doping, and Defect Density Control

Perovskite solar cells have gained significant attention due to their excellent photovoltaic
 performance and simple manufacturing process. However, the use of lead (Pb) in the widely
 studied CH3NH3PbI3 perovskite material limits its large-scale production due to low
 stability in the air. As a result, researchers have turned to lead-free CH 3 NH 3 SnI 3 perovskite
 as a promising alternative. In this study, we used one-dimensional simulation software to
 investigate the photovoltaic properties of CH 3 NH 3 SnI 3 perovskite solar cells with a
 TiO 2 /CH 3 NH 3 SnI 3 /Cu 2 O structure. By adjusting the thickness of the absorbing layer, doping
 concentration, and density of defects, we were able to improve the performance of the solar
 cells. The obtained results of Jsc= 31,519 mA/cm 2 , Voc = 0,965V, FF = 78,717%, and PCE
 = 23,943% demonstrate the potential of lead-free CH 3 NH 3 SnI 3 as a highly efficient and
 environmentally friendly solar absorber.

Lead-free MAGeI3 as a suitable alternative for MAPbI3 in nanostructured perovskite solar cells: a simulation study

The lead is a heavy metal with hazardous impacts on environment and human life. Lead-free perovskite solar cells have attracted much attention in recent years, due to eco-friendly characteristics. Meanwhile, Pb-containing cells showed the highest efficiencies among the various types of cells. Hence, designing novel Pb-free solar cells with comparable or better performance than the Pb-containing ones is highly required. In this work, a lead-free methyl-ammonium-germanium-iodide (MAGeI3)-based perovskite solar cell with ITO/TiO2/MAGeI3/Spiro-OMeTAD/Ag multilayer nanostructure has been proposed and its main characteristics including open-circuit voltage (VOC) and power conversion efficiency (η) have been evaluated and compared with those of MAPbI3-based cell, in simulation study. The VOC and η of the MAGeI3-based cell (1.18V and 11.9%) have been found comparable with those of the MAPbI3 one (1.10V and 14.6%). These results can excite more attention to Ge as a more environment-friendly element than Pb, in highly efficient upcoming perovskite solar cells.

Lead-Free Perovskite Homojunction-Based HTM-Free Perovskite Solar Cells: Theoretical and Experimental Viewpoints.

Simplifying the design of lead-free perovskite solar cells (PSCs) has drawn a lot of interest due to their low manufacturing cost and relative non-toxic nature. Focus has been placed mostly on reducing the toxic lead element and eliminating the requirement for expensive hole transport materials (HTMs). However, in terms of power conversion efficiency (PCE), the PSCs using all charge transport materials surpass the environmentally beneficial HTM-free PSCs. The low PCEs of the lead-free HTM-free PSCs could be linked to poorer hole transport and extraction as well as lower light harvesting. In this context, a lead-free perovskite homojunction-based HTM-free PSC was investigated, and the performance was then assessed using a Solar Cell Capacitance Simulator (SCAPS). A two-step method was employed to fabricate lead-free perovskite homojunction-based HTM-free PSCs in order to validate the simulation results. The simulation results show that high hole mobility and a narrow band gap of cesium tin iodide (CsSnI3) boosted the hole collection and absorption spectrum, respectively. Additionally, the homojunction's built-in electric field, which was identified using SCAPS simulations, promoted the directed transport of the photo-induced charges, lowering carrier recombination losses. Homojunction-based HTM-free PSCs having a CsSnI3 layer with a thickness of 100 nm, defect density of 1015 cm-3, and interface defect density of 1018 cm-3 were found to be capable of delivering high PCEs under a working temperature of 300 K. When compared to formamidinium tin iodide (FASnI3)-based devices, the open-circuit voltage (Voc), short-circuit density (Jsc), fill factor (FF), and PCE of FASnI3/CsSnI3 homojunction-based HTM-free PSCs were all improved from 0.66 to 0.78 V, 26.07 to 27.65 mA cm-2, 76.37 to 79.74%, and 14.62 to 19.03%, respectively. In comparison to a FASnI3-based device (PCE = 8.94%), an experimentally fabricated device using homojunction of FASnI3/CsSnI3 performs better with Voc of 0.84 V, Jsc of 22.06 mA cm-2, FF of 63.50%, and PCE of 11.77%. Moreover, FASnI3/CsSnI3-based PSC is more stable over time than its FASnI3-based counterpart, preserving 89% of its initial PCE. These findings provide promising guidelines for developing highly efficient and environmentally friendly HTM-free PSCs based on perovskite homojunction.

A Qualitative Theoretical Study of Inorganic HTM-Free RbGeI3 Based Perovskite Solar Cells Using SCAPS 1D as a Pathway Towards 3.601% Efficiency

The presence of toxic lead in perovskite solar cells has hindered its commercial viability. In this present work, a mesoscopic inorganic lead-free perovskite solar cells based on RbGeI3 was proposed and implemented using SCAPs simulation tool. The effect of electron transport material (ETM) and Absorber thickness were analyzed. When the device was first simulated, its power conversion efficiency (PCE), fill factor (FF), current density (Jsc), and open circuit voltage (Voc) all reached values of 3.584% for PCE, 48.477% for FF, 25.385 mA/cm2 for Jsc, and 0.291 V for Voc. When the ETM and absorber are at their ideal thicknesses of 0.08 and 0.40, the development of efficiency becomes stable. Using the aforementioned parameters, the optimized PSC device produced the following values: PCE = 3.601%, Jsc = 25.386 mA/cm2, Voc = 0.291 V, and FF = 48.637%. The PCE improvement over the basic device without optimization is around 1.01 times. The findings indicate that perovskite solar cell lacking HTM has a substantial capacity to absorb photon energy and produce electrons. It has also shown how to create environmentally clean and economically viable technology.

Lead-free perovskite solar cells, what's next?

Although lead halide perovskite solar cells (PSCs) have achieved an efficiency of 25.7 %, the highly toxic composition, element lead, will hinder the use of PSCs in indoor photovoltaics, building-integrated photovoltaics and wearable devices. Therefore, it is imperative to search and study the low-toxicity lead-free perovskites as back-up materials. Recently, encouraging progress is made on lead-free PSCs in terms of Sn perovskites and double perovskites. In this comment, we will summarize the present status and give future perspectives on lead-free perovskite photovoltaics.

Theoretical study of a lead-free perovskite solar cell using ZnSe as ETL and PTAA as HTL

Cesium tin-germanium triiodide (CsSn0.5Ge0.5I3) is an efficient inorganic halide perovskite with good stability that has received wide attention in recent years. In the present study, a lead-free perovskite solar cell structure was designed with zinc selenide (ZnSe) as the electron transport layer (ETL), CsSn0.5Ge0.5I3 as the perovskite absorber layer and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) as the hole transport layer (HTL). For a more practical understanding of the solar cell, several parameters such as absorber thickness, defect density, doping concentration of the absorber layer, interface defects and working point temperature were examined. The SCAPS-1D simulator was used for the analysis of the proposed device. The power conversion efficiency of the device was obtained as 23.15% with V OC = 1.07 V, J SC = 27.24 mA/cm2 and fill factor = 78.82% at an 800 nm thickness of the CsSn0.5Ge0.5I3 absorber layer. Selection of best material and easy fabrication process is necessary for development of highly efficient and environmentally friendly perovskite solar cells.

High-performance lead-free perovskite solar cell: a theoretical study

In the present work, a lead-free perovskite solar cell was designed using methylammonium tin iodide (CH3NH3SnI3), poly-3- hexylthiophene and titanium dioxide (TiO2) as absorber layer, hole transport layer and electron transport layer respectively. Perovskite solar cells have made impressive strides recently, and their performance has significantly improved. A fundamental n–i–p planar heterojunction structure of photovoltaic cells was designed and simulated with solar cell capacitance simulation software (Scaps-1D). In this study, different parameters such as thickness, acceptor density, temperature and defect density were varied to improve the device performance. Optimum values of different parameters were used to attain good results for the photovoltaic device such as power convergence efficiency (PCE), V OC, fill factor and J SC of 27.54%, 1.0216 V, 86.56% and 31.14 mA/cm2, respectively. The acceptor density was varied from 1 × 10−12 to 1 × 10−20 cm−3 for the proposed device structure. The PCE of this device structure increased when different charge transport materials were used. This simulation study showed that the proposed cell structure could be used to construct a photovoltaic cell with a higher efficiency.

Pseudohalide-Modulated Crystallization for Efficient Quasi-2D Tin Perovskite Solar Cells with Minimized Voltage Deficit

Regulating the crystallization dynamics and suppressing the oxidation of Sn2+ is imperative for the emerging lead-free tin perovskite solar cells (TPSCs). In this respect, quasi-2D tin perovskites exhibit relatively slow crystallization and crystal growth rate compared to the three-dimensional analogues. However, these dimensional-mixed tin perovskites suffer from random orientation, which limits the charge carrier transport for photovoltaic applications. Herein, we report a facile and feasible strategy to modulate the dimensionality and crystallization of tin perovskites with the incorporation of phenethylammonium thiocyanate (PEASCN), which is exploited to deliver a high-quality crystal growth and preferred alignment. The pseudohalide SCN– can effectively hinder Sn2+ oxidation by synergistically modulating the coordination and crystal growth of Sn perovskite films. Meanwhile, these interactions significantly suppressed the nonradiative charge recombination. Finally, a high efficiency approaching 12.88% with an open-circuit voltage (Voc) of 863 mV is achieved for the inverted TPSCs. The obtained Voc is among the highest reported values for indene-C60 (ICBA)-free TPSC devices. The PEASCN devices also exhibited high stability for over 2000 h under a N2 atmosphere.

Numerical Simulation and Optimization of Inorganic Lead-Free Cs3Bi2I9-Based Perovskite Photovoltaic Cell: Impact of Various Design Parameters

The lead halide-based perovskite solar cells have attracted much attention in the photovoltaic industry due to their high efficiency, easy manufacturing, lightweight, and low cost. However, these lead halide-based perovskite solar cells are not manufactured commercially due to lead-based toxicity. To investigate lead-free inorganic perovskite solar cells (PSCs), we investigated a novel Cs3Bi2I9-based perovskite configuration in SCAPS-1D software using different hole transport layers (HTLs). At the same time, WS2 is applied as an electron transport layer (ETL). Comparative analysis of the various design configurations reveals that ITO/WS2/Cs3Bi2I9/PEDOT:PSS/Au offers the best performance with 20.12% of power conversion efficiency (PCE). After optimizing the thickness, bandgap, defect density, and carrier density, the efficiency of the configuration is increased from 20.12 to 24.91%. Improvement in other performance parameters such as short circuit current (17.325 mA/cm2), open circuit voltage (1.5683 V), and fill factor (91.66%) are also observed after tuning different attributes. This investigation indicates the potential application of Cs3Bi2I9 as a lead-free and stable perovskite material that can contribute to improving the renewable energy sector.

Uncovering the Role of Electronic Doping In Lead-free Perovskite (CH3NH3)2CuCl4-xBrx and Solar Cells Fabrication

Uncovering the Role of Electronic Doping In Lead-free Perovskite (CH3NH3)2CuCl4-xBrx and Solar Cells Fabrication

Numerical assessment and optimization of highly efficient lead-free hybrid double perovskite solar cell

In this work, a performance assessment of a double perovskite Cs2BiCuI6 solar cell with the typical lead-based perovskite CH3NH3PbI3 as an active layer is presented using SCAPS-1D software. The theoretical analysis depicts the improvement in power conversion efficiency (PCE) for Cs2BiCuI6-based solar cells. This shows that in the coming future, the hybrid double perovskite Cs2BiCuI6 possess the capability to replace toxic CH3NH3PbI3-based solar cell which would help to create lead-free harmless solar cells. Detailed structural parameters optimization such as the absorbing layer thickness, and charge carrier mobility, and variation in interface defect density is carried out to enhance the device efficiency. This gives a PCE of 24.84 % for a hybrid double perovskite-based solar cell. The optimized values are 1013 cm−3, and 5 cm2 V−1 s−1 for interface defect density and carrier mobility respectively which also enhances the fill factor to 82 % with open circuit voltage of 1.28 V and 24.54 mA/cm2 short circuit current density Jsc.

An extensive study on multiple ETL and HTL layers to design and simulation of high-performance lead-free CsSnCl3-based perovskite solar cells

Cesium tin chloride (CsSnCl3) is a potential and competitive absorber material for lead-free perovskite solar cells (PSCs). The full potential of CsSnCl3 not yet been realized owing to the possible challenges of defect-free device fabrication, non-optimized alignment of the electron transport layer (ETL), hole transport layer (HTL), and the favorable device configuration. In this work, we proposed several CsSnCl3-based solar cell (SC) configurations using one dimensional solar cell capacitance simulator (SCAPS-1D) with different competent ETLs like indium–gallium–zinc–oxide (IGZO), tin-dioxide (SnO2), tungsten disulfide (WS2), ceric dioxide (CeO2), titanium dioxide (TiO2), zinc oxide (ZnO), C60, PCBM, and HTLs of cuprous oxide (Cu2O), cupric oxide (CuO), nickel oxide (NiO), vanadium oxide (V2O5), copper iodide (CuI), CuSCN, CuSbS2, Spiro MeOTAD, CBTS, CFTS, P3HT, PEDOT:PSS. Simulation results revealed that ZnO, TiO2, IGZO, WS2, PCBM, and C60 ETLs-based halide perovskites with ITO/ETLs/CsSnCl3/CBTS/Au heterostructure exhibited outstanding photoconversion efficiency retaining nearest photovoltaic parameters values among 96 different configurations. Further, for the six best-performing configurations, the effect of the CsSnCl3 absorber and ETL thickness, series and shunt resistance, working temperature, impact of capacitance, Mott–Schottky, generation and recombination rate, current–voltage properties, and quantum efficiency on performance were assessed. We found that ETLs like TiO2, ZnO, and IGZO, with CBTS HTL can act as outstanding materials for the fabrication of CsSnCl3-based high efficiency (η ≥ 22%) heterojunction SCs with ITO/ETL/CsSnCl3/CBTS/Au structure. The simulation results obtained by the SCAPS-1D for the best six CsSnCl3-perovskites SC configurations were compared by the wxAMPS (widget provided analysis of microelectronic and photonic structures) tool for further validation. Furthermore, the structural, optical and electronic properties along with electron charge density, and Fermi surface of the CsSnCl3 perovskite absorber layer were computed and analyzed using first-principle calculations based on density functional theory. Thus, this in-depth simulation paves a constructive research avenue to fabricate cost-effective, high-efficiency, and lead-free CsSnCl3 perovskite-based high-performance SCs for a lead-free green and pollution-free environment.