Lead-free Perovskite Solar Cells Research Articles

Unveiling the potential of Cs2AgBiBr6 perovskites for next-generation see-through photovoltaics

Lead-free perovskite solar cells are strong contenders in the race for green and sustainable energy. Among these, cesium silver bismuth bromide (Cs2AgBiBr6) stands out, but its potential was hampered by the need for high-temperature processing, hindering its transition to scalable techniques. In this work, we present the feasibility of blade-coating deposition of Cs2AgBiBr6 layer. Thanks to the temperature control of the substrate during the process, we deposited uniform films at precise thickness enabling the fabrication of fully semitransparent devices with power conversion efficiencies (PCEs) of 3.07 % and 7.7 % under 1 sun and indoor light conditions, respectively. Furthermore, we evaluated important metrics for transparent photovoltaics such as Light Utilization Efficiency (LUE) and Color Rendering Index (CRI) of the devices by varying the Cs2AgBiBr6 thicknesses and the illumination conditions. The results showed LUEs at 1 Sun illumination of 1.1 % (1.5 %) and CRI of 71 (62.5) for 200 nm-thick and 400 nm-thick perovskite films, respectively. Finally, we evaluated the process scalability fabricating 6 cm2-sized semitransparent modules suitable for low-power electronics in Internet of Things field. This study opens the door to the development of non-hazardous, scalable, lead-free perovskite solar cells and modules suitable for integration into our everyday surroundings thanks to their see-through properties.

A-Site Engineering with Thiophene-Based Ammonium for High-Efficiency 2D/3D Tin Halide Perovskite Solar Cells.

TTin halide perovskites are the most promising candidate materials for lead-free perovskite solar cells (PSCs) thanks to their low toxicity and ideal bandgap energies. The introduction of 2D/3D mixed perovskite phases in tin-based PSCs (TPSCs) has proven to be the most effective approach to improving device efficiency and stability. However, a 2D perovskite phase normally shows relatively low carrier mobility, which will be unfavorable for carrier transfer in the devices. In this work, we used a thiophene-based cation 2-(thiophen-3-yl)ethan-1-aminium (3-TEA) as a spacer to form a novel 2D perovskite phase in TPSCs, which shows the most promising effect on the performance enhancement in comparison with other cations like 2-(thiophen-2-yl)ethan-1-aminium (2-TEA) and benzene-based 2-phenylethan-1-aminium (PEA). Theoretical calculations reveal that 3-TEA enables the most compact crystal packing of [SnI6]4- octahedral layers, resulting in the lowest hole effective mass and formation energy in the 2D phase. This effect significantly enhances device efficiency and stability by facilitating more efficient carrier transfer within the 2D phase. These findings indicate that thiophene-based 2D perovskites are well-suited for high-performance TPSCs.

Design and Simulation for Minimizing Non-Radiative Recombination Losses in CsGeI2Br Perovskite Solar Cells.

CsGeI2Br-based perovskites, with their favorable band gap and high absorption coefficient, are promising candidates for the development of efficient lead-free perovskite solar cells (PSCs). However, bulk and interfacial carrier non-radiative recombination losses hinder the further improvement of power conversion efficiency and stability in PSCs. To overcome this challenge, the photovoltaic potential of the device is unlocked by optimizing the optical and electronic parameters through rigorous numerical simulation, which include tuning perovskite thickness, bulk defect density, and series and shunt resistance. Additionally, to make the simulation data as realistic as possible, recombination processes, such as Auger recombination, must be considered. In this simulation, when the Auger capture coefficient is increased to 10-29 cm6 s-1, the efficiency drops from 31.62% (without taking Auger recombination into account) to 29.10%. Since Auger recombination is unavoidable in experiments, carrier losses due to Auger recombination should be included in the analysis of the efficiency limit to avoid significantly overestimating the simulated device performance. Therefore, this paper provides valuable insights for designing realistic and efficient lead-free PSCs.

Enhancing SrZrS3 perovskite solar cells: A comprehensive SCAPS-1D analysis of inorganic transport layers

In the quest for sustainable energy, perovskite solar cells have emerged as promising candidates due to their high power conversion efficiencies and excellent optoelectronic properties. This study focuses on SrZrS3, a lead-free chalcogenide perovskite, and its integration with various inorganic transport layers for enhanced photovoltaic performance. Using SCAPS-1D simulation software, the effects of different electron transport layers (ETLs) and hole transport layers (HTLs) on device efficiency were systematically explored. The device with a-Si:H as the HTL and ZnS as the ETL (aSi-3) shows the highest efficiency of 20.01 % resulting from better energy band alignment and reduced recombination losses. This study highlights the importance of optimizing transport layers for enhancing SrZrS3-based solar cells, offering insights for developing high-performance, lead-free perovskite solar cells.

Lead-free Cs2TiBr6 perovskite solar cells achieving high power conversion efficiency through device simulation

Recently, lead-based perovskite solar cells (PSCs) have gained significant attention in the photovoltaic industry due to their remarkable properties such as high bandgap and high absorption coefficient. However, challenges such as toxicity, instability, and short shelf life limit the use of inorganic-organic lead-based PSCs. To address these issues, researchers introduced eco-friendly, lead-free, and stable cesium titanium (Cs2TiBr6) single-halide absorber material. The aim of this work is to perform the numerical modelling and simulation of FTO/SnO2/Cs2TiBr6/CBTS/Au structure incorporating interfacial defect layers (IDL) using SCAPS-1D to examine and study its characteristics properties about various photovoltaic (PV) parameters such as light-absorbing layer thickness, charge transport layer thickness, doping, defect density, operating temperature, and quantum efficiency (QE). After evaluating these parameters, the proposed single-halide Cs2TiBr6-based structure shows superior performance as compared to previously reported experimental and simulation-based Cs2TiBr6 perovskite structures. The results show a maximum power conversion efficiency (PCE) of 24.24 %, with a fill factor (FF) of 88.9 %, an open-circuit voltage (VOC) of 1.31 V, and a short-circuit current density (JSC) of 20.76 mA/cm2. This work encourages researchers to develop low-toxic, and stable PSCs for the future solar cell industry.

An inorganic Lead-free Cs2SnI6-based perovskite solar cell Optimization by SCAPS-1D

Cs2SnI6 is an environmentally friendly and reliable perovskite solar cell (PSCs) material. Its optimal band gap and strong light absorption make it a promising candidate for the absorption layer. However, the current challenge is to improve its photoelectric conversion efficiency. To address this, this study investigates the performance of PSCs based on Cs2SnI6 using SCAPS-1D simulation. The influence of various factors on PSC performance is examined, including different hole transport layers(HTLs) and electron transport layers(ETLs), perovskite layer thickness, ETL doping density, HTL doping density, absorber doping density, perovskite layer defect density, different back contacts and temperature. Finally, a Cs2SnI6-based solar device with an inorganic configuration of FTO/NiO/Cs2SnI6/SnO2/Au has been developed, reaching the power conversion efficiency(PCE) of 28.69%. The study demonstrates that Cs2SnI6 PSCs exhibit promising photovoltaic performance, offering valuable insights for the solar energy sector in the production of cost-effective, efficient, and environmentally friendly Cs-based perovskite solar cells.

Machine learning-enhanced design of lead-free halide perovskite materials using density functional theory

The investigation of emerging non-toxic perovskite materials has been undertaken to advance the fabrication of environmentally sustainable lead-free perovskite solar cells. This study introduces a machine learning methodology aimed at predicting innovative halide perovskite materials that hold promise for use in photovoltaic applications. The seven newly predicted materials are as follows: CsMnCl4, Rb3Mn2Cl9, Rb4MnCl6, Rb3MnCl5, RbMn2Cl7, RbMn4Cl9, and CsIn2Cl7. The predicted compounds are first screened using a machine learning approach, and their validity is subsequently verified through density functional theory calculations. CsMnCl4 is notable among them, displaying a bandgap of 1.37 eV, falling within the Shockley-Queisser limit, making it suitable for photovoltaic applications. Through the integration of machine learning and density functional theory, this study presents a methodology that is more effective and thorough for the discovery and design of materials.

Carboxylic Acid-Assisted Synthesis of Tin(II) Iodide: Key for Stable Large-Area Lead-Free Perovskite Solar Cells.

Despite significant progress in tin-based perovskites, the development of stable and high-performance tin-based perovskite solar cells (TPSCs) remains a challenge. In this pursuit, a multitude of strategies have been explored, encompassing the use of reducing agents, antioxidants, bulky cations, and customized solvent systems. We propose an improved approach for synthesizing SnI2 from elemental tin and iodine. Here, we generate tin nanoparticles grafted with a carboxylic acid in situ from tin powder-carboxylic acid-assisted synthesis (CAAS). This methodology not only improves the synthesis process of SnI2 but also enhances precursor stability against oxidation. We use 119Sn MAS NMR to study the atomic-level structure of the resulting FASnI3 thin films and find that the CAAS approach leads to highly pure and unoxidized material. We report remarkable reproducibility in fabricating large-area (1 cm2) flexible TPSCs with significant improvement in open-circuit voltage leading to the champion device showing a power conversion efficiency of 8.35%.

Enhancing power conversion efficiency of lead-free perovskite solar cells: a numerical simulation approach

Enhancing power conversion efficiency of lead-free perovskite solar cells: a numerical simulation approach

Improving Hybrid Tin Halide Films of Lead-Free Perovskite Solar Cells with a Volatile Additive of Dipropyl Sulfide.

Lead-free perovskite solar cells with hybrid tin halides (Sn-PVKs) as harvesters have attracted attention with respect to eliminating the contamination of conventional hybrid lead halides. However, Sn-PVK films usually have inferior performance due to rapid crystallization and uncontrollable morphology. Moreover, Sn2+ ions suffer from irreversible oxidation that results in self-doping and device instability. Additive engineering is a key strategy for improving the quality of Sn-PVK films, but solid residues of additives could degrade the transport-recombination process. In this work, dipropyl sulfide (DPS) was introduced as a volatile additive into the precursor solution, and no residue exists in the Sn-PVK films after thermal annealing. The coordinating ability of DPS molecules stabilized Sn2+ ions to form the intermediate complex, which retards the crystallization and oxidation of Sn-PVK films. Consequently, the power conversion efficiencies of devices increase from 11.0% to 12.9% with less recombination and a lower leakage current, and the stability of the devices is improved simultaneously.

Efficiency enhancement and optimization of lead-free Cs2PtI6 perovskite solar cell

Perovskite solar cells (PSCs) are famous for their potential to produce efficient, flexible, and low-cost solar energy. This study explores the possibility of eco-friendly, lead-free, inorganic solar cells using Cs2PtI6 as the light-absorbing layer and NiO as the hole transport layer (HTL). It carefully optimizes various factors, including the thickness, doping concentration, defect density, and the effects of radiative recombination of the absorber layer, along with different hole and electron transport layers. The study also examines interfacial defects and resistances within the device. The density of defects at the interface between the HTL and the absorber layer is a crucial factor influencing the device’s performance. Additionally, the study evaluates different metal back contacts, changes in temperature, light intensity, and the spectrum of light. The optimized structure (FTO/ZnO/Cs2PtI6/NiO/Au) achieves an open circuit voltage (VOC) of 1.34 V, a short-circuit current (JSC) of 32.34 mAcm−2, a fill factor (FF) of 75.70%, and an excellent power conversion efficiency (PCE) of 32.70%, showing great promise in solar cell technology.

Green-solvent-processed lead-free perovskite solar cells

Tin-based perovskite has been considered as one of the most potential candidates for lead-based perovskite. The solution proceed method was widely utilized in fabricating tin perovskite solar cells. So far, all fabrication processes for tin perovskite solar cells involved toxic organic solvents, which is contrary to the development of environmentally friendly perovskite solar cells. In this study, we report for the first time, by using a mixed green solvent N-diethyl formamide and green 1,3-dimethyl-3,4,5,6-Tetrahydro-2 (1H)-pyrimidinone as precursor solvent, and a green solvent dibutyl ether as antisolvent, a high-quality FA0.75MA0.25SnI3 film was achieved. The optical band gap of the prepared perovskite layer was 1.36 eV, which was close to the ideal band gap. The green-solution-proceed perovskite films showed reduced defect density. As a consequence, the champion green-solution-proceed photovoltaic device achieved a power conversion efficiency of 4.4%. Moreover, it still maintains 80% of the initial efficiency after 600 h of storage in a nitrogen atmosphere. This work would promote the perovskite solar cells from a ‘new’ technique to a ‘new and green’ technique.

Simulation of SnO2/Cs2AgInBr6/CuO heterojunction solar cell using AMPS-1D modeling

Using the one-dimensional computer code AMPS-1D MPS-1D (Analysis of Microelectronic and Photonic Structures), we simulated a lead-free double perovskite cell made of Cs2AgInBr6. This study examines the influence of the thickness and acceptor density of the active layer (Cs2AgInBr6) on key solar cell parameters, including short-circuit current density (JSC), efficiency (Eff), fill factor (FF), open-circuit voltage (VOC), current-voltage characteristics (J-V)). Our results suggest that an optimal active layer thickness of 500 nm yields good performance for the studied solar cell. Furthermore, the ideal acceptor density for enhancing output parameters is in the range of 10¹3-10¹⁵ cm⁻³. Post-optimization, our findings reveal a Voc of 0.969 V, a Jsc of 29.402 mA cm⁻², and an FF of 0.876, resulting in an efficiency of 24.959%. The results from AMPS-1D simulations for a Cs2AgInBr6 lead-free double perovskite solar cell suggest that this material and device structure can achieve high efficiency and good performance characteristics.

Numerical insights of lead-free manganese-based perovskite solar cell

Numerical insights of lead-free manganese-based perovskite solar cell

Co-Cation Engineering via Mixing of Acetamidinium and Rubidium in FASnI3 for Tin Perovskite Solar Cells to Attain 14.5% Efficiency.

Tin perovskite solar cells (TPSCs) were developed by adding the co-cations acetamidinium (AC) and rubidium (Rb) in varied proportions based on the FASnI3 structure (E1). We found that adding 10% AC and 3% Rb can optimize the device (E1AC10Rb3) to attain an efficiency of power conversion of 14.5% with great shelf- and light-soaking stability. The films at varied AC and Rb proportions were characterized using XPS, SEM, AFM, GIWAXS, XRD, TOPAS, TOF-SIMS, UV-vis, PL, TCSPC, and femtosecond TAS techniques to show the excellent optoelectronic properties of the E1AC10Rb3 film in comparison to those of the other films. AC was found to have the effect of passivating the vacancy defects on the surface and near the bottom of the film, while Rb plays a pivotal role in passivating the bottom interface between perovskite and PEDOT:PSS. Therefore, the E1AC10Rb3 device with a band gap of 1.43 eV becomes a promising candidate as a narrow band gap device for tandem lead-free perovskite solar cell development.

Engineering the active layer of lead-free perovskite (CH3NH3SnI3) solar cells using numerical simulation

We conduct a thorough numerical simulation to examine the impact of the thickness, defect density, and doping density of the active layer on the photovoltaic performance of the lead-free CH3NH3SnI3 perovskite solar cell (PSC). We observe that increasing the thickness of the active layer initially from 100 nm to 400 nm improved the power conversion efficiency (PCE) from 10.4% to 11.6%. However, further increasing the thickness to 800 nm resulted in a slight decline in PCE to 11.1%. This unexpected trend can be attributed to the high carrier mobility of charges in the CH3NH3SnI3 perovskite, which enables fast extraction of charge carriers, offsetting losses due to charge recombination. Increasing active layer trap density substantially declines the PCE from 11.5% at 1014 cm−3 to 7.5% at 1018 cm−3, as a result of the noticeable drop in open-circuit voltage (VOC) and fill factor (FF) with a growing defect density due to the enhancement in trap-assisted recombination. This is backed by a striking reduction in the shunt resistance upon increasing the defect density. Raising the active layer doping firstly enhances the PCE, reaching a peak value of 12.5% at the active layer doping density of 1017 cm−3, after which the PCE decreases as the doping density continues to increase. We explain these observations by energy level diagrams deduced at various doping levels.

Stable lead free perovskite solar cells based on bismuth doped perovskite materials

The inclusion of lead in the Champion perovskite material MAPbI3 is a detrimental factor in the commercialization of lead based perovskite solar cells. This is mainly due to the toxicity of lead and also due to degradation of MAPbI3 in ambient condition into hazardous chemicals which are toxic to the environment [1]. Due to these factors, though the Hybrid Organic Inorganic Lead based PSCs exhibit excellent photovoltaic effect and photo conversion efficiency (PCE), yet numerous theoretical and experimental studies have been done to replace lead with suitable elements such as Sn, Ge, Bi etc. This research work focusses on replacing Pb from MAPbI3, with different wt% of Bi such as 1%, 2%, 4% and 8% and analyzing its effect on the stability and efficiency of the PSC. These solutions of Bi doped perovskite are coated on the FTOs and are fabricated under room ambient condition in the sandwich structure. The results exhibit lower efficiency of Bismuth doped PSCs but it shows remarkable stability comparable to that of MAPbI3.

An analysis comparing the performance of lead and tin halides organic Perovskite Solar Cells and numerical simulation with SCAPS

The scientific community focused on finding environmentally safe alternative metal halides to address the instability and toxicity associated with lead perovskite materials. These alternatives are supposed to replace lead halides without altering the distinctive properties of lead perovskite materials. Additionally, they should contribute to producing longer-lasting and stable perovskite in solar cells. This research presents a practical investigation of using tin- and lead-based composites in perovskite iodide solar cells with Titanium dioxide (TiO2) and Copper oxide (CuO) as electron transport materials (ETM) and hole transport materials (HTM), respectively. The performance parameters of the perovskite solar cells (PSCs) are compared with those of lead-based and lead-free PSCs with the same charge transport layers of ETM and HTM, as well as compare the practical results with the software results of Solar Cell Capacitance Simulation (SCAPS) package. In this study, the performance of PSCs with an absorption layer ((CH3NH3PbI3)t/(CH3NH3SnI3)1-t) was examined. The thickness of the perovskite layer is represented by (t), which can take the values(t = 1, 0.5, or 0) μm. The results of the laboratory study were compared to the performance of PSCs based on numerical analysis of SCAPS modeling. PSCs were prepared with a configuration structure (FTO/compact TiO2/(CH3NH3PbI3)t/(CH3NH3SnI3)1-t/CuO/Cu-electrode). A tetragonal phase was obtained for perovskite materials CH3NH3PbI3 and CH3NH3SnI3 with a direct optical energy gap estimated at (1.55 and 1.35) eV, respectively. The l-V curve of the prepared PSCs was studied, and the performance of the solar cells was examined under a light intensity of 100 mW/cm2. The power conversion efficiency, PCE, of the prepared solar cells, was (PCE = 2.9, 3.11, or 0.5) at (t = 1, 0.5, or 0)μm, respectively. A comparative analysis was also performed between the empirical performance of the manufactured PSCs and the theoretical results acquired by the SCAPS package software.

Homogenizing The Low-Dimensional Phases for Stable 2D-3D Tin Perovskite Solar Cells.

2D-3D tin-based perovskites are considered as promising candidates for achieving efficient lead-free perovskite solar cells (PSCs). However, the existence of multiple low-dimensional phases formed during the film preparation hinders the efficient transport of charge carriers. In addition, the non-homogeneous distribution of low-dimensional phases leads to lattice distortion and increases the defect density, which are undesirable for the stability of tin-based PSCs. Here, mixed spacer cations [diethylamine (DEA+) and phenethylamine (PEA+)] are introduced into tin perovskite films to modulate the distribution of the 2D phases. It is found that compared to the film with only PEA+, the combination of DEA+ and PEA+ favors the formation of homogeneous low-dimensional perovskite phases with three octahedral monolayers (n=3), especially near the bottom interface between perovskite and hole transport layer. The homogenization of 2D phases help improve the film quality with reduced lattice distortion and released strain. With these merits, the tin PSC shows significantly improved stability with 94% of its initial efficiency retained after storing in a nitrogen atmosphere for over 4600h, and over 80% efficiency maintained after continuous illumination for 400h.

Conformal zinc sulfide coating of vertically aligned ZnO nanorods by two-step hydrothermal synthesis on wide bandgap seed layers for lead-free perovskite solar cells

Vertically aligned ZnO nanorods (NRs) were grown hydrothermally on the wide bandgap (∼3.86 – 4.04 eV) seed layers (SLs) of grain size ∼162 ± 35 nm, prepared using ball-milled derived ZnO powder. The synthesized ZnO NRs were further decorated with ZnS nanocrystals to achieve a ZnO NR-ZnS core–shell (CS)-like nano-scaffolds by a subsequent hydrothermal synthesis at 70 °C for 1 h. UV-Vis-NIR spectroscopy, x-ray diffractometry (XRD), Raman spectroscopy and Field emission scanning electron microscopy (FESEM) coupled with Energy dispersive x-ray spectroscopy (EDX) analyses confirmed the formation of ZnS atop the vertically aligned ZnO NR arrays of ∼1.79 ± 0.17 µm length and ∼165 ± 27 nm diameter. Transmission electron microscopy (TEM)/EDX analyses revealed that vertically aligned ZnO NRs (core dia. ∼181 ± 12 nm) arrays are conformally coated by an ultrathin ZnS (∼25 ± 7 nm) shell layer with a preferential ZnS{111}/ZnO{10-10}-like partial epitaxy. The ZnO NRs exhibited a sharp band edge near ∼384 nm having optical bandgap energy (E g) of ∼3.23 eV. However, the ZnO NR-ZnS CS exhibited double absorption bands at E g ∼ 3.20 eV (ZnO-core) and E g ∼ 3.78 eV (ZnS-shell). The ZnS{111}/ZnO{10-10}-nano-scaffolds could be utilized to facilitate the enhanced absorption of UV photons as well as the radial junction formation between the Pb-free perovskite absorber and ZnS/ZnO NRs layers.