Lead-free Perovskite Solar Cells Research Articles

The Defect Passivation of Tin Halide Perovskites Using a Cesium Iodide Modification.

Tin-based perovskites are promising for realizing lead-free perovskite solar cells; however, there remains a significant challenge to achieving high-performance tin-based perovskite solar cells. In particular, the device fill factor was much lower than that of other photovoltaic cells. Therefore, understanding how the fill factor was influenced by device physical mechanisms is meaningful. In this study, we reported a method to improve the device fill factor using a thin cesium iodide layer modification in tin-based perovskite cells. With the thin passivation layer, a high-quality perovskite film with larger crystals and lower charge carrier densities was obtained. As a result, the series resistance of devices was decreased; the shunt resistance of devices was increased; and the non-radiative recombination of devices was suppressed. Consequently, the fill factor, and the device efficiency and stability were greatly enhanced. The champion tin-based perovskite cells showed a fill factor of 63%, an efficiency of 6.1% and excellent stability. Our study reveals that, with a moderate thin layer modification strategy, the long-term stability of tin-based PSCs can be developed.

A lead-free inorganic Cs2TiX6-based heterostructure perovskite solar cell design and performance evaluation

A lead-free inorganic Cs2TiX6-based heterostructure perovskite solar cell design and performance evaluation

High-performance optimization and analysis of Cs2AgBiBr6-based lead-free double perovskite solar cells

High-performance optimization and analysis of Cs2AgBiBr6-based lead-free double perovskite solar cells

An optical study of the Cs3Sb2Br9-based n-i-p and p-i-n structures for lead-free perovskite solar cells

An optical study of the Cs3Sb2Br9-based n-i-p and p-i-n structures for lead-free perovskite solar cells

Performance optimization and defect studies of Pb-free CsSnBr3-based perovskite solar cells

Perovskite solar cells (PSCs) have become increasingly popular in the photovoltaic industry due to their high power conversion efficiency (PCE) and potential for low-cost manufacturing. However, despite the significant promise of lead-based PSCs, several challenges must be addressed before commercialization can occur. These challenges include toxicity and defects. As such, this study focuses on optimizing an environmentally friendly (non-toxic) PSC based on CsSnBr3 perovskite material. To achieve this objective, we examined various factors that influence the performance of the PSC, such as material bandgap, transport materials, individual layer thickness, and defect density associated with temperature effects. We also conducted a thorough analysis of the photovoltaic performance of the device. Our findings reveal that bulk and interface defects significantly impact the device's performance. Through our investigation and analysis, we were able to design an optimized device that exhibits a PCE of 17.94 %. This impressive performance was accompanied by a short-circuit current density (JSC) of 18 mA/cm2, an open-circuit voltage (VOC) of 1.3 V, and a fill factor (FF) of 74.5 %. Throughout the study, we utilized SCAPS-1D simulations to conduct a detailed optoelectronic study and analyze the device's performance. Furthermore, we employed 3D finite-difference time-domain (FDTD) optical simulations to validate the optical performance of the optimized device. Our study demonstrates that lead-free PSCs have significant potential in photovoltaics. By optimizing the manufacturing process and addressing the challenges associated with these materials, we can unlock even more tremendous potential for this technology. Overall, our numerical study can be a valuable resource for researchers and industry professionals in this field.

Design and Performance Optimization of Lead-Free Perovskite Solar Cells with Enhanced Efficiency

Design and Performance Optimization of Lead-Free Perovskite Solar Cells with Enhanced Efficiency

Integration of Capacitive Pressure Sensor-on-Chip with Lead-Free Perovskite Solar Cells for Continuous Health Monitoring.

The increasing prevalence of hypertension necessitates continuous blood pressure monitoring. This can be safely and painlessly achieved using non-invasive wearable electronic devices. However, the integration of analog, digital, and power electronics into a single system poses significant challenges. Therefore, we demonstrated a comprehensive multi-scale simulation of a sensor-on-chip that was based on a capacitive pressure sensor. Two analog interfacing circuits were proposed for a full-scale operation ranging from 0 V to 5 V, enabling efficient digital data processing. We also demonstrated the integration of lead-free perovskite solar cells as a mechanism for self-powering the sensor. The proposed system exhibits varying sensitivity from 1.4 × 10-3 to 0.095 (kPa)-1, depending on the pressure range of measurement. In the most optimal configuration, the system consumed 50.5 mW, encompassing a 6.487 mm2 area for the perovskite cell and a CMOS layout area of 1.78 × 1.232 mm2. These results underline the potential for such sensor-on-chip designs in future wearable health-monitoring technologies. Overall, this paper contributes to the field of wearable health-monitoring technologies by presenting a novel approach to self-powered blood pressure monitoring through the integration of capacitive pressure sensors, analog interfacing circuits, and lead-free perovskite solar cells.

Design a highly efficient lead-free organic tin halide perovskite solar cells using nickel oxide as the hole transport layer

The work asserts the theoretical study of lead-free perovskite (PVK) solar cells (PSCs) by inorganic oxides as hole transport layer (HTL), with a primary focus on nickel oxide (NiO) under the AM 1.5G spectrum. To comprehend the drift-diffusion phenomenon of the PSC and a clear insight into the best device structure, NiO reveals the extreme bandgap (Eg) alignment and barrier height of the HTLs. The report highlights a high short-circuit current density (JSC) of 32.56 mA/cm2, an fill factor (FF) of 79.55%, an open-circuit voltage (VOC) of 1.15 V, and an excellent power conversion efficiency (PCE) of 29.78% for NiO as HTL for an optimized PVK thickness of 400 nm at about 1 × 1012 cm−3 defect density. Achieving higher external quantum efficiency (EQE) of nearly 90% in the wavelength range of 300–780 nm is the foremost objective of this analysis. The device provides a real impedance of 0.24 Ωcm−2 and an imaginary impedance of −1 Ωcm−2 along with a positive capacitance value of 2.75 × 10−17 Fcm−2 at 1.15 V to adequately escalate the device's reliability and stability. Hence, the design of a most promising PSC of AZO/SnO2/MASnI3/NiO/Ag configurations with the potential to govern the device performance roadmap and the credibility to fabricate a highly effective hybrid PSC.

Rare earth element-doped SnO2 for enhancing the efficiency and stability of Cs2AgBiBr6 lead-free perovskite solar cells

The mesoporous architecture of perovskite solar cells (PSCs) can promote the crystallization of the perovskite layer by providing numerous heterogeneous nucleation sites. The morphology of the electron transport layer (ETL) and its interface with the perovskite layer are two of the key factors in improving the performance of PSCs. While SnO2 is a commonly used ETL material owing to its wide band gap, high transparency and high electron mobility. However, the uncontrollable nature of oxygen vacancies in tin oxide during preparation can lead to severe carrier recombination at certain sites, thus adversely affecting the open-circuit voltage (Voc) of the device. In this work, by constructing a three-dimensional structure of tin oxide and doping it with samarium as the electron transport layer, the Cs2AgBiBr6 perovskite solar cell was assembled to solve the problem of severe carrier recombination, and the prepared Sm-doped mesoporous tin dioxide (Sm@m-SnO2) electron transport layer was flatter, denser and smoother than that of the non-samarium-doped one, and the perovskite film was more uniform with higher crystallinity. The device achieves an optimum photovoltaic conversion efficiency of 2.19% while demonstrating excellent environmental tolerance and long-term stability without encapsulation.

Mechanistic Understanding of Oxidation of Tin-based Perovskite Solar Cells and Mitigation Strategies.

Tin (Sn)-based perovskites as the most promising absorber materials for lead-free perovskite solar cells (PSCs) have achieved the record efficiency of over 14 %. Although suppressing the oxidation of Sn-based perovskites is a frequently concerned topic for Sn-based PSCs, many studies have given vague explanations and the mechanisms are still under debate. This is in principal due to the lack of an in-depth understanding of various and complex intrinsic and extrinsic factors causing the oxidation process. In this context, we critically review the chemical mechanism of facile oxidation of Sn-based perovskites and differentiate its detrimental effects at material- and device-level. More importantly, we classify and introduce the intrinsic factors (raw materials and solvent of perovskite precursors) and extrinsic factors (exposure to neutral oxygen and superoxide) causing the oxidation with their corresponding anti-oxidation improvement methods. The presented comprehensive understanding and prospect of the oxidation provide insightful guidance for suppressing the oxidation in Sn-based PSCs "from the beginning to the end".

Highly efficient lead-free perovskite solar cell based on magnesium-doped copper delafossite hole transport layer: a SCAPS-1D framework prospect

Highly efficient lead-free perovskite solar cell based on magnesium-doped copper delafossite hole transport layer: a SCAPS-1D framework prospect

Designing an Efficient Lead-Free Perovskite Solar Cell through a Computational Method

Organometallic halide perovskite (PVK)-based solar cells (PSC) have gained significant popularity owing to their efficiency, adaptability, and versatility. However, the presence of lead in conventional PVK poses environmental risks and hinders effective commercialization. Although lead-free PVK solar cells have been developed, their conversion efficiency is limited due to intrinsic losses. To address this challenge, we present a simulation study focusing on methylammonium tin bromide (MASnBr3) as an alternative material. In our investigation, the MASnBr3 layers are strategically placed between a copper iodide (CuI)-based hole transporting material (HTM) and a zinc oxide (ZnO)-based electron transporting material (ETM). We optimize the active layer thickness, operating temperature, defect density analysis, and series resistances to assess device performance. Furthermore, we employ contour mapping, considering both thickness and defect density, for a detailed investigation. Our primary objective is to achieve unprecedented efficiency in lead-free MASnBr3-based PSCs. Remarkably, our study achieves the highest JSC (short-circuit current density) of 34.09 mA/cm2, VOC (open-circuit voltage) of 1.15 V, FF (fill factor) of 82.06%, and optimized conversion efficiency of 32.19%. These advancements in conversion efficiency pave the way for the development of lead-free PVK solar cells in the desired direction.

Synergic Electron and Defect Compensation Minimizes Voltage Loss in Lead-Free Perovskite Solar Cells.

Sn perovskite solar cells have been regarded as one of the most promising alternatives to the Pb-based counterparts due to their low toxicity and excellent optoelectronic properties. However, the Sn perovskites are notorious to feature heavy p-doping characteristics and possess abundant vacancy defects, which resulted in under-optimized interfacial energy level alignment and severe nonradiative recombination. Here, we reported a synergic "electron and defect compensation" strategy to simultaneously modulate the electronic structures and defect profiles of Sn perovskites via incorporating a traced amount (0.1 mol%) of heterovalent metal halide salts. Consequently, the doping level of modified Sn perovskites was altered from heavy p-type to weak p-type (i.e. up-shifting the Fermi Level by ~ 0.12 eV) that determinately reducing the barrier of interfacial charge extraction and effectively suppressing the charge recombination loss throughout the bulk perovskite film and at relevant interfaces. Pioneeringly, the resultant device modified with electron and defect compensation realized a champion efficiency of 14.02%, which is ~46% higher than that of control device (9.56%). Notably, a record-high photovoltage of 1.013 V was attained, corresponding to the lowest voltage deficit of 0.38 eV reported to date, and narrowing the gap with Pb-based analogues (~ 0.30 V).

Ionic Liquid-Mediated Intermediate Phase Adduct Constructing for Highly Stable Lead-Free Perovskite Solar Cells

Ionic Liquid-Mediated Intermediate Phase Adduct Constructing for Highly Stable Lead-Free Perovskite Solar Cells

Improved PCE in stable lead-free perovskite solar cells based on band engineering of ETL and absorber

In this paper, a unique structure of graded band gap (GBG) electron transport layer (ETL) based lead-free Perovskite solar cell (PSC) is proposed and numerically investigated. The structure consists of cesium Formamidinium tin iodide (FACsSnI3) with band-gap grading aspect sandwiched between electron and hole transport layers. Various ETLs such as Zn(S,O), ZnO, ZnMgO and C60 have been considered and investigated with and without GBG aspect. It is revealed that the use of band engineering based on band gap grading ETL and absorber films allows the dual-advantages of enhanced photogeneration and carrier extraction mechanisms. The merits of the proposed PSC structure are compared to other published results in terms of improved photovoltaic parameters. The obtained results show improvements in photoconversion properties of the PSCs when GBG-Zn(S,O) is considered as an ETL. The effective conduction band alignment of GBG-Zn(S,O)/GBG-FACsSnI3 heterostructure interface leads to an improved carrier collection efficiency and subsequently improved efficiency. The optimized PSC structure presents power conversion efficiency as high as 21.67 %, with an open circuit voltage of 0.96 V, short-circuit current of 30.75 mA/cm2, and fill factor of 72.88%. The obtained photovoltaic parameters of the proposed GBG-ETL/GBG-FACsSnI3 heterostructure can provide new perspectives for the realization of efficient cost-effective lead-free PSCs.

Improving the efficiency of a FTO/PCBM/Cs2AgBiBr6/NiOx/Au lead-free double perovskite solar cell using numerical simulation through optimizing the absorption layer thickness and work function of electrodes

Lead-free perovskite solar cells are proposed to reduce environmental toxicity. However, the efficiency of these solar cells is significantly lower than that of those based on lead. The maximum Photo Conversion Efficiency(PCE) reported experimentally for lead free solar cells is 6.37%, which is significantly lower than that of lead-based solar cells. Attempts have been made to improve the PCE of lead-free solar cells using numerical simulations in order to build a lead-free solar cell with the highest efficiency attainable. Recently, a lead-free solar cell with the configuration ITO/SnO2/Cs2AgBiBr6/P3HT/Au and a maximum PCE of 11.69% was numerically investigated. In this study, we suggested a lead-free solar cell structure using FTO/PCBM/Cs2AgBiBr6/NiOx/Au configuration and showed that,when operated in the wavelength range 400–700 nm, a PCE of 15.49% with Jsc = 8.17 mA/cm2, Voc = 2.49 V and FF = 76.16% can be attained by optimizing the thickness of the absorption layer and the work function of the electrode. While in the same configuration the PCE can be increased to 21.92% when operated in the wavelength range of 350–750 nm.This investigation's findings can be used to manufacture more efficient and stable lead-free solar cells forfuturenon-hazardous environmental applications.

Tin Halide Perovskite Solar Cells with Open-Circuit Voltages Approaching the Shockley-Queisser Limit.

The power conversion efficiency of tin-based halide perovskite solar cells is limited by large photovoltage losses arising from the significant energy-level offset between the perovskite and the conventional electron transport material, fullerene C60. The fullerene derivative indene-C60 bisadduct (ICBA) is a promising alternative to mitigate this drawback, owing to its superior energy level matching with most tin-based perovskites. However, the less finely controlled energy disorder of the ICBA films leads to the extension of its band tails that limits the photovoltage of the resultant devices and reduces the power conversion efficiency. Herein, we fabricate ICBA films with improved morphology and electrical properties by optimizing the choice of solvent and the annealing temperature. Energy disorder in the ICBA films is substantially reduced, as evidenced by the 22 meV smaller width of the electronic density of states. The resulting solar cells show open-circuit voltages of up to 1.01 V, one of the highest values reported so far for tin-based devices. Combined with surface passivation, this strategy enabled solar cells with efficiencies of up to 11.57%. Our work highlights the importance of controlling the properties of the electron transport material toward the development of efficient lead-free perovskite solar cells and demonstrates the potential of solvent engineering for efficient device processing.

The effect of cations in electronic, and optical properties of lead-free halide perovskites based on Sn–Ge

In this work, the electronic and optical properties of three-dimensional (3D) lead-free hybrid perovskites [Formula: see text][Formula: see text] with organic and inorganic cations [Formula: see text], Cs ([Formula: see text]) have been investigated using density functional theory (DFT). The nature of the cations in the 3D perovskite structure has a significant impact on the electronic and optical properties of the 3D structures because octahedral [Formula: see text] is so sensitive to them. The results revealed that by replacing the organic cation with the inorganic cation, the band gap has increased, and also in the optical properties, an increase in the absorption coefficient and a decrease in reflection have been observed. According to the obtained results, the [Formula: see text] compound is a better candidate for optoelectronic devices and solar cells applications than [Formula: see text], due to its higher band gap, higher absorption coefficient, lower reflection, and cheaper price. These findings are crucial for comprehending how cations affect lead-free perovskite halides, and we hope it will be a useful guide for improving the photovoltaic efficiency of lead-free perovskite solar cells. In addition to the absorber layer of solar cells, 3D perovskites are used in laser and thermoelectric applications, topological insulation, and radiation detection.

SCAPS simulation and DFT study of lead-free perovskite solar cells based on CsGeI3

With the rapid development of perovskite solar cells (PSCs), environmentally friendly germanium-based PSCs have begun to appear in people's vision. We have designed a perovskite solar cell structure consisting of FTO/Cd0.5Zn0.5S/CsGeI3/MoO3/Au. Our study focused on analyzing the impact of various factors such as the absorption layer, electron transport layer (ETL), hole transport layer (HTL), interfacial defect layer (IDL), and temperature, on device performance. We optimized various parameters of the device, and as a result, the final PCE reached an impressive 35.91%. In addition, we conducted an analysis of the perovskite absorber layer using density functional theory (DFT) and investigated the function of Ge atoms in the perovskite absorber layer. The results show that, for HTL, altering the doping concentration of the ETL has a more significant impact on PSCs. When the operating temperature exceeds 300K, only the short-circuit current (Jsc) increases. When the defect density exceeds 1013cm−3, the rate of carrier recombination begins to increase significantly, along with the interface defect layer. We also analyzed the energy band, density of states, charge density difference, charge population, and elastic constants of the absorption layer using density functional theory (DFT). The results indicate that Ge atoms play a crucial role in photon absorption and photocurrent generation, which is a significant factor contributing to the high power conversion efficiency of germanium-based PSCs. Due to the transfer of electric charge from the Ge atom to the periphery of the I atom and the hybridization between the Ge-4p and I-5p orbitals, the Ge–I bond is formed and stabilized. Finally, the calculation of elastic constants shows that CsGeI3 is a stable mechanical structure.

A Numerical Approach to Analysis of an Environment-Friendly Sn-Based Perovskite Solar Cell with SnO2 Buffer Layer Using SCAPS-1D

In this research, we have proposed a Sn-based perovskite solar cell using solar cell capacitance software. The main aim of this study is to develop an environment-friendly and highly efficient structure that can be used as an alternative to other toxic lead-based perovskite solar cells. This work performed a numerical analysis for the proposed (Al/ZnO/SnO2/CH3NH3SnI3/Ni) device structure. The absorber layer CH3NH3SnI3, buffer layer SnO2, and electron transport layer (ETL) ZnO, with aluminium as the front contact and nickel as the back contact, have been used in this simulation. Several analyses have been conducted for the proposed structure, such as the impact of the absorber layer thickness, acceptor density, defect density, series and shunt resistances, back contact work function, and operating temperature. The device simulation revealed that the optimum thickness of the absorber layer is 1.5 μm and 0.05 μm for the buffer layer. The proposed Sn-based perovskite structure has obtained a conversion efficiency of 28.19% along with FF of 84.63%, Jsc of 34.634 mA/cm2, and Voc of 0.961 V. This study shows the upcoming lead-free perovskite solar cell’s enormous potential.