Lead-based Perovskite Solar Cells Research Articles

Design and optimization of Cs2SnI6 based inorganic perovskite solar cell model: numerical simulation

To overcome the drawbacks of high lead toxicity and poor corrosion resistance of lead-based perovskite solar cells (PSCs), and to compensate for the poor air stability of Sn2+ compound-based perovskite, Cs2SnI6 (Sn4+ compound) is selected as the absorber for the PSC in this study. Using FTO/ETL/Cs2SnI6/HTL/Au as the model, the high-performance non-toxic inorganic PSC structure is explored through theoretical simulation and calculation by SCAPS-1D. The conduction band offsets (CBO) and valence band offsets (VBO) of commonly used electron transport layer materials (ETMs), hole transport layer materials (HTMs), and Cs2SnI6 are calculated based on electron affinity potential (χ) and bandgap (E g ). Then, by analyzing the pn junction composed of ETL and HTL and the bandgap structure at the n-i, i-p interfaces, the most matching n-i-p planar heterojunction model, FTO/IGZO/Cs2SnI6/Cu2BaSnS4/Au, was selected. Finally, by analyzing and adjusting the material thickness, defect density of each layer, operation temperature, the optimal performance of PSC was determined to be 30.39% power conversion efficiency (PCE), 1.27 V open circuit voltage (V oc ), 28.46 mA cm−2 short circuit current (J sc ), and 84.02% fill factor (FF). A new and more efficient PSC is proposed in this study, providing some terrific clues for finding high-quality alternatives to lead-based PSCs.

Optimization of vertical gradient Pb-Sn hybrid perovskite solar cells using SCAPS (Solar Cell Capacitance Simulator)

Lead-tin hybrid perovskite solar cells emerge as a promising alternative to traditional lead-based cells, addressing environmental and stability concerns, however their efficiency lags. During the fabrication of lead-tin mixed perovskites, the Pb/Sn ratio varies across the film due to different solubilities under various processing conditions. To tackle this issue, we propose a novel perovskite absorber with a vertical gradient in the lead-tin ratio. Our study employs SCAPS-1D simulations to investigate the performance of ITO/HTL/gradient perovskite/ETL/Ag cell structures with different transport layer materials. We systematically analyze the impact of doping levels, defect density states, and interfacial defects in the absorber layer on device efficiency. Through optimization of the device structural parameters, reflecting real experimental conditions, we achieved an energy conversion efficiency of 24.84%. This efficiency is comparable to that of lead-based perovskite solar cells. Interestingly, simulations suggest that omitting the electron transport layer still yields an efficiency above 23.5%, potentially simplifying the fabrication process. This finding indicates that vertically graded Pb-Sn hybrid perovskite solar cells hold great promise for high-efficiency solar cell applications.

Simulation and Optimization of Lead-Based Perovskite Solar Cells with Cuprous Oxide as a P-type Inorganic Layer

The hole transporting material (HTM) is responsible for selectively transporting holes and blocking electrons which also plays a crucial role in the efficiency and stability of perovskite solar cells (PSCs). Spiro-MeOTAD is the most popular material, which is expensive and can be easily affected by moisture content. There is a need to find an alternative HTM with sufficiently high resistance to moisture content. In this paper, the influence of some parameters with cuprous oxide (Cu2O) as HTM was investigated using a solar cell capacitance simulator (SCAPS). These include the influence of doping concentration and thickness of the absorber layer, the effect of thickness of ETM and HTM as well as electron affinities of ETM and HTM on the performance of the PSCs. From the obtained results, it was found that the concentration of dopant in the absorber layer, the thickness of ETM and HTM and the electron affinity of HTM and ETM affect the performance of the solar cell. The cell performance improves greatly with the reduction of ETM electron affinity and its thickness. Upon optimization of parameters, power conversion efficiency for this device was found to be 20.42% with a current density of 22.26 mAcm-2, voltage of 1.12 V, and fill factor of 82.20%. The optimized device demonstrates an enhancement of 58.80%, 2.25%, 20.40% and 30.23% in PCE, Jsc, FF, and Voc over the initial cell. The results show that Cu2O in lead-based PSC as HTM is an efficient system and an alternative to spiro-MeOTAD.

Bicyclopentadithiophene-Based Organic Semiconductor for Stable and High-Performance Perovskite Solar Cells Exceeding 22.

Well-performing organic-inorganic halide perovskites are susceptible to poor efficiency and instability due to their various defects at the interphases, grain boundaries (GBs), and surfaces. In this study, an in situ method is utilized for effectively passivating the under-coordinated Pb2+ defects of perovskite with new non-fullerene acceptors (NFAs) (INXBCDT; X = H, Cl, and Br) through their carbonyl and cyano functional groups during the antisolvent dripping process. It reveals that the bicyclopentadithiophene (BCDT) core with highly electron-withdrawing end-capping groups passivates GBs and boosts perovskite grain growth. This effective defect passivation decreases the trap density to increase the carrier recombination lifetime of the perovskite film. As a result, bromo-substituted dicyanomethylene indanone (INBr)-end-capped BCDT (INBrBCDT-b8; 3a)-passivated devices exhibit the highest power conversion efficiency (PCE) of 22.20% (vs those of 18.09% obtained for perovskite films without passivation) upon an optimized film preparation process. Note that devices treated with more soluble 2-ethylhexyl-substituted compounds (1a, 2a, and 3a) exhibit higher PCE than those treated with less soluble octyl-substituted compounds (1b, 2b, and 3b). It is also worth noting that BCDT is a cost-effective six-ring core that is easier to synthesize with a higher yield and therefore much cheaper than those with highly fused-ring cores. In addition, a long-term stability test in a glovebox for 1500 h reveals that the perovskite solar cells (PSCs) based on a perovskite absorber treated with compound 3a maintain ∼90% of their initial PCE. This is the first example of the simplest high-conjugation additive for perovskite film to achieve a PCE greater than 22% of the corresponding lead-based PSCs.

Thickness dependent numerical investigations of lead free perovskite/CIGS bilayer solar cell using SCAPS-1D

Due to the toxicity and the complex fabrication process lead-based perovskite solar cells are difficult to fabricate commercially though the power conversion efficiency has reached 25.2 ​%. In the current scenario, lead free perovskite solar cell devices are gaining interest among the researchers and the bilayer structure is showing significant improvement in the efficiency. In this work, with the help of SCAPS 1D, a lead free single-layer perovskite (CH3NH3SnBr3) solar cell and a bilayer structure (CH3NH3SnBr3/CIGS) have been investigated to compare the photovoltaic performance by using PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) and SnTe as an electron transport layer (ETL) and hole transport layer (HTL) respectively. Different device parameters i.e. thickness, defect density, doping concentration and series-shunt resistance of the device was optimized to obtain the best performance. In the case of a single absorber layer, power conversion efficiency (PCE), open circuit voltage (Voc), fill factor (FF) and the short circuit current density (Jsc) were achieved 20.58 ​%, 0.931 ​V, 64.95 ​% and 34.03 mA.cm−2 respectively. However, it is observed that bilayer structure (FTO/PCBM/CH3NH3SnBr3/CIGS/ZnTe/SnTe/Au) obtains 22.68 ​% of PCE, 0.916 ​V of Voc, 71.46 ​% of FF and 34.66 mA.cm−2 of Jsc. This study suggests that a proper bilayer structure is beneficial to improve the device performance in terms of Jsc and FF by increasing the carrier generation and reducing the back surface field recombination.

Nonadiabatic molecular dynamics study on effect of Ge/Sn alloy on hot carrier relaxation of CsPbBr<sub>3</sub> perovskite

Perovskite solar cells have been a prominent focus in the field of photovoltaics in recent decades, owing to their exceptional performance: easy synthesis, and cost-effectiveness. The all-inorganic cesium-based perovskite CsPbBr<sub>3</sub>, known for its remarkable thermal stability, has become a star material in the field of optoelectronics due to its outstanding luminescent properties. Despite the high efficiency of lead-based perovskite solar cells, the toxicity associated with lead and the poor long-term stability of these devices remain significant barriers to their large-scale commercialization. As is well known, non-radiative electron-hole recombination significantly shortens the carrier lifetime, acting as a primary pathway for excited state charge to loss energy. This phenomenon directly affects the photovoltaic conversion efficiency and charge transfer performance of perovskite materials. Therefore, maximizing the reduction of non-radiative recombination energy loss in perovskite solar cells has become a crucial research focus. In this study, a systematic exploration is conducted by using a non-adiabatic molecular dynamics approach combined with time-dependent density functional theory to investigate the excited-state carrier dynamics of CsPbBr<sub>3</sub> and its alloyed structures, CsPb<sub>0.75</sub>Ge<sub>0.25</sub>Br<sub>3</sub> and CsPb<sub>0.5</sub>Ge<sub>0.25</sub>Sn<sub>0.25</sub>Br<sub>3</sub>. The study comprehensively analyzes the non-radiative electron-hole recombination scenarios and the mechanisms for reducing charge energy loss based on crystal structure, electronic properties, and excited-state properties. The research findings reveal that alloying with Sn/Ge can reduce the bandgap, increase non-adiabatic coupling, and shorten the decoherence time. The interplay of reduced quantum decoherence, smaller bandgap, and larger non-adiabatic coupling effectively decelerates the electron-hole recombination process. Consequently, the carrier lifetime of the CsPb<sub>0.75</sub>Ge<sub>0.25</sub>Br<sub>3</sub> system extends by 1.6 times. Moreover, under the joint influence of Sn/Ge, the carrier lifetime of the CsPb<sub>0.5</sub>Ge<sub>0.25</sub>Sn<sub>0.25</sub>Br<sub>3</sub> system extends by 4.2 times compared with those of the original system. The overall sequence follows CsPb<sub>0.5</sub>Ge<sub>0.25</sub>Sn<sub>0.25</sub>Br<sub>3</sub> > CsPb<sub>0.75</sub>Ge<sub>0.25</sub>Br<sub>3</sub> > CsPbBr<sub>3</sub>. This study underscores the significant influence of binary alloying of B-site metal cations (in the perovskite structure <i>ABX</i><sub>3</sub>, where B-site refers to the metal cation) on the non-radiative electron-hole recombination of CsPbBr<sub>3</sub>.This research presents an effective alloying scheme that substantially prolongs the carrier lifetime of perovskites, offering a rational approach to optimizing solar cell performance. It lays the groundwork for the future design of perovskite solar cell materials.

Numerical Simulation of Lead-Free Tin and Germanium Based All Perovskite Tandem Solar Cell

The ability to customize the materials bandgaps makes perovskite solar cells a promising candidate for hybrid-tandem applications. This allows them to effectively utilize parts of the solar spectrum that silicon-based solar cells cannot efficiently capture, resulting in higher absorption coefficients. However, there is a lack of research on lead-free all-perovskite tandem solar cells, and secondary data on materials is limited. One of the main challenges in previous studies is the high cost and solid structure of traditional silicon-based solar cells, which require significant storage space. Additionally, lead-based perovskite solar cells pose environmental concerns due to their water solubility and potential harmful effects upon consumption. To address these issues, thin-film perovskite solar cells with liquid solvents are employed in the solar cell design. Lead is replaced with germanium and tin-based perovskites, which exhibit comparable photovoltaic performance to silicon. In the present work, the OghmaNano simulation tool was utilized to conduct numerical simulation of the perovskite design. The perovskite solar cell layers were structured as follows: FTO/ZnO/MAGeI3/Spiro-OMeTAD/FAMASnGeI3/Cu2O/Au. The variables considered included optimum layer thicknesses and bandgaps, as well as the most suitable materials for the ETL and HTL, aiming to obtain the highest efficiency. Based on the simulation results, the proposed perovskite structure shows remarkable photovoltaic parameters. The Voc was measured at 0.84 V Jsc of 16.1 mA/cm2, FF of 0.825, and PCE that reached 11.12%. This project contributes to future research on materials for the ETL and HTL of lead-free, tin and germanium based APTSCs.

SCAPS-1D Modeling of Hydrogenated Lead-Free Cs2AgBiBr6 Double Perovskite Solar Cells with a Remarkable Efficiency of 26.3.

In this investigation, we employ a numerical simulation approach to model a hydrogenated lead-free Cs2AgBiBr6 double perovskite solar cell with a p-i-n inverted structure, utilizing SCAPS-1D. Contrary to traditional lead-based perovskite solar cells, the Cs2AgBiBr6 double perovskite exhibits reduced toxicity and enhanced stability, boasting a maximum power conversion efficiency of 6.37%. Given its potential for improved environmental compatibility, achieving higher efficiency is imperative for its practical implementation in solar cells. This paper offers a comprehensive quantitative analysis of the hydrogenated lead-free Cs2AgBiBr6 double perovskite solar cell, aiming to optimize its structural parameters. Our exploration involves an in-depth investigation of various electron transport layer materials to augment efficiency. Variables that affect the photovoltaic efficiency of the perovskite solar cell are closely examined, including the absorber layer's thickness and doping concentration, the hole transport layer, and the absorber defect density. We also investigate the impact of the doping concentration of the electron transport layer and the energy level alignment between the absorber and the interface on the photovoltaic output of the cell. After careful consideration, zinc oxide is chosen to serve as the electron transport layer. This optimized configuration surpasses the original structure by over four times, resulting in an impressive power conversion efficiency of 26.3%, an open-circuit voltage of 1.278 V, a fill factor of 88.21%, and a short-circuit current density of 23.30 mA.cm-2. This study highlights the critical role that numerical simulations play in improving the chances of commercializing Cs2AgBiBr6 double perovskite solar cells through increased structural optimization and efficiency.

Performance enhancement of CsPbI3-xBrx perovskite solar cells via graded bandgap and affinity engineering

All inorganic cesium lead-based perovskite solar cells (PSCs) have gained attention as alternative absorbing materials owing to their exceptional thermal stability. However, these devices are suffer from transmission and thermalization losses. Therefore, a novel grading approach is used in CsPbI3-x Brx perovskite solar cell to reduce the transmission and thermalization losses by enhancing the cell’s ability to capture a broad spectrum of light wavelengths and suitably accommodate the material’s energy bandgap. In this work, the performance of CsPbI3-xBrx perovskite solar cell with graded bandgap (Eg) and affinity has been explored and analyzed using the simulation SCAPS-1D tool. Different compositions (x) are varied to adjust the bandgap of CsPbI3-xBrx with different grading profiles such as linear, parabolic and beta grading. The graded structure enhances the absorption wavelength range and carrier lifetime. However, it also leads to the redistribution of the electrical field within the device, promoting more effective charge separation and collection. By utilizing this approach, the impact of absorber thickness variations from (50 nm to 700 nm) is also studied and analyzed with respect to grading profiles. Initially, 16.75% power conversion efficiency (PCE) is obtained by calibrating the experimental CsPbI3-xBrx graded solar cell. Then, performance is further improved by adjusting the bandgap with grading profiles, optimizing ETLs/HTLs and achieving optimum PV parameters: short-circuit current density (JSC) of 20.50 mA cm−2, open-circuit voltage (VOC) of 1.35 V, fill factor (FF) of 84.15% and PCE of 23.11%. The findings of the reported study would significantly provide a path for the development of graded PSC.

Modeling and Investigation of Highly Efficient Environment Friendly Perovskite Solar Cell with CuSbS2 as Hole Transport Layer

The presence of lead and its associated toxicity represents a hindrance to the broad commercial production of lead halide perovskites and their utilization in solar photovoltaic devices. Although lead halide perovskites have found extensive application in solar cell technology, questions have arisen regarding the hazardous nature and durability of lead (Pb) in photovoltaic systems. This research seeks to address these concerns by exploring alternative materials, such as tin-based perovskites, to pave the way for cleaner and more sustainable energy solutions. The scientific community has shown increased interest in tin-based perovskites due to their superior efficiency and stability compared to lead-based perovskite solar cell. This research introduces a planar heterojunction solar cell utilizing tin-based perovskites that are free of lead. The simulation task was conducted using SCAPS-1d software. Device parameters for a lead-free PSC (perovskite solar cell) using significant framework FTO/WS2/CH3NH3SnI3(perovskite)/CuSbS2 included an examination of factors like perovskite layer thickness, the obsession of acceptors in the perovskite layer, defects density of perovskite layer, and the band gap of the perovskite layer. In this setup, WS2 served as the ETL material, CuSbS2 functioned as the HTL material, and the CH3NH3SnI3(Perovskite) was used as the absorber layer material. This configuration achieved an impressive PCE 32.5%, along with a Jsc34.1mAcm-², Voc1.02V and FF85.5%. These optimized results likelihood indicates the strong prospect for development of an eco-friendly and efficient model of PSC (perovskite solar cell).

A modified drop-casting technique for efficient lead-free, environment-friendly thin film CsBi3I10 perovskite solar cells

The efficiency of lead-based perovskite solar cell deteriorates due to their instability and toxicity which inhibits their commercial application. Both of these issues are resolved by substituting Bismuth in place of lead. In order to create environmentally friendly perovskite solar cells (PSCs), bismuth-based halide perovskite (CsBi3I10) is a promising absorber material. Bismuth-based CsBi3I10 perovskite films were fabricated using a modified drop-casting process at room temperature. With this technique, you can get a film with desirable characteristics including a smooth, uniform surface and no pinholes. A comprehensive analysis is carried out in this research article as a result of the fact that thermal annealing is the first step in the process of transforming the deposited solution into the perovskite material. Band gap tuning is achieved with the use of this heat treatment. As film that has been post-annealed at the low temperature of 60 °C is not only tuned in terms of conductivity with a low band gap of 1.78 eV, but it also has improved absorption. In contrast, hexagonal particles with a low absorbance and a greater band gap of 2.08 eV develop at higher post-annealing temperatures. Band gap is greater (2.21 eV) and nonhomogeneous layered structure is formed in the film that does not undergo any post annealing treatment. The effects of post-annealing temperature on morphological, structural, and optical properties are explored and connected with photovoltaic application requirements. Finally, the photovoltaic performance of PSCs based on CsBi3I10 without hole transport layer (HTL) is investigated quantitatively in this study.

Numerical simulation and optimization of lead-based perovskite solar cell with inorganic HTL using SCAPS-1D

Numerical simulation and optimization of lead-based perovskite solar cell with inorganic HTL using SCAPS-1D

A Review of the Technological Advances in the Design of Highly Efficient Perovskite Solar Cells

The search for renewable and sustainable energy for energy security and better environmental protection against hazardous emissions from petro-based fuels has gained significant momentum in the last decade. Towards this end, energy from the sun has proven to be reliable and inexhaustible. Therefore, better light harvesting technologies have to be sought. Herein, the current trends in the development of perovskite solar cells with a focus on device engineering, band alignment, device fabrication with superior light harvesting properties, and numerical simulation of solar cell architectures are critically reviewed. This work will form the basis for future scientist to have a better scientific background on the design of highly efficient solar cell devices, which are cost-effective to fabricate, highly stable, and eco-friendly. This review presents thorough essential information on perovskite solar cell technology and tracks methodically their technological performance overtime. The photovoltaic (PV) technology can help to reduce pollution related to greenhouse gas emissions, criterion pollutant emissions, and emissions from heavy metals and radioactive species by nearly 90%. Following the introduction of highly efficient perovskite solar cell (PSC) technologies, the problems associated with stability, short life-time and lead-based perovskite solar cell configurations have significantly been minimized. The fabrication and simulation of perovskite solar cells has been made possible with advanced technologies and state-of-the-art computational codes. Furthermore, device simulation strategies have lately been used to understand, select appropriate materials, and gain insights into solar cell devices’ physical behavior in order to improve their performances. Numerical simulation softwares such as the 1-dimenional solar cell capacitance simulator (SCAPS-1D), Silvaco ATLAS, and wx-analysis of microelectronic and photonic structures (wxAMPS) used to understand the device engineering of solar cells are critically discussed. Because of the need to produce charge collection selectivity, hole transport materials (HTMs) as well as electron transport materials (ETMs) constitute essential PSC components. In this work, the synthesis of inorganic HTMs, as well as their characteristics and uses in various PSCs comprising mesoporous and planar designs, are explored in detail. It is anticipated that the performance of inorganic HTLs on PSCs would encourage further research which will have a significant influence on the future designs and fabrication of highly efficient solar cells.

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.

Regulating Crystallization and Lead Leakage of Perovskite Solar Cell Via Novel Polyoxometalate-Based Metal-Organic Framework.

Despite the unprecedented progress in lead-based perovskite solar cells (PSCs), the toxicity and leakage of lead from degraded PSCs triggered by deep-level defects and poor crystallization quality increase environmental risk and become a critical challenge for eco-friendly PSCs. Here, a novel 2D polyoxometalate (POM)-based metal-organic framework (MOF) (C5 NH5 )4 (C3 N2 H5 )2 Zn3 (H8 P4 Mo6 O31 )2 ·2H2 O (POMOF) is ingeniously devised to address these issues. Note that the integration of POM endows POMOF with great advantages of electrical conductivity and charge mobility. Ordered POMOF induces the crystallization of high-quality perovskite film and eliminates lead-based defects to improve internal stability. The resultant PSCs achieve a superior power conversion efficiency (23.3%) accompanied by improved stability that maintains ≈90% of its original efficiency after 1600h. Meanwhile, POMOF with phosphate groups effectively prevents lead leakage through in situ chemical anchoring and adsorption methods to reduce environmental risk. This work provides an effective strategy to minimize lead-based defects and leakage in sustainable PSCs through multi-functional POM-based MOF material.

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.

Effects of alkali-metals (X = Li, Na, K) doping on the electronic, optoelectronic, thermodynamic, and X-ray spectroscopic properties of X–SnI3 halide perovskites

The effect of alkali metals (Li, Na, K) doping at X sites in tin-based X–SnI3 halide perovskite on structural, electronic, phonon, thermodynamic, and X-ray core-level spectroscopic properties was investigated and correlated with optoelectronic efficiency in the development of a stable and environmentally friendly solar technology to replace toxic lead-based perovskite solar cells (PSCs). These calculations were carried out based on the density functional theory approach using the Quantum Espresso software with the generalized gradient approximation (GGA) exchange correlation Perdew Burke Ernzerhorf functional. In addition, the phonon frequency, thermodynamics, and X-ray spectroscopy calculations were completed in Materials Studio using the CASTEP code. Our results reveal that there is a clear correlation between the alkali metal's ionic radius, changes in the lattice structural parameters, and the electronic band gap, such that the lattice constants are 5.940, 5.868, and 5.897 Å and the band gaps are 1.20, 1.14, and 1.10 eV for LiSnI3, NaSnI3, and KSnI3, respectively. The highest lattice constant obtained for LiSnI3, indicates that Li atoms occupied interstitial positions in the perovskite crystal, whereas the direct band gap decreases as cationic size increases, with KSnI3 exhibiting the least band gap. Phonon calculations show that KSnI3 has the lowest negative vibration region in its phonon dispersion plot, indicating dynamic stability. Interestingly, all the structures are found to portray high optical absorption, high extinction coefficient, high polarizability. Additionally, the free energy computation of the perovskites shows a reduction with rising temperature, but enthalpy increases significantly with increasing temperature. Yet, due to phonon lattice vibrations, the heat capacity increased as the temperature rose. Although the XSnI3 (X = Li, Na, and K) perovskites under investigation will perform efficiently as semiconductors and can be used for optoelectronic applications, the KSnl3 perovskite material has the most desirable properties for the fabrication of solar cell devices.

Reduced interfacial recombination losses and lead leakage in lead-based perovskite solar cells using 2D/3D perovskite engineering

Although perovskite solar cells (PSCs) have achieved significant success, there are still some barriers to their commercialization, such as poor stability and unsatisfactory power conversion efficiency (PCE). Here, we report low-dimensionality engineering of perovskites using mercaptoethylammonium iodide (MEMI). Two-dimensional (2D) perovskite materials can simultaneously passivate the interface defects of the perovskite film and enhance carrier extraction. The PCE of the device increased from 20.85% for the control device to a resultant of 22.41% for the target device. Meanwhile, device stability was ameliorated after MEMI modification, and the stability of unencapsulated target devices decreased by 7.5% after aging in the dark air condition for 300 h. Finally, the notorious lead leakage was significantly suppressed. This work guides to create efficient and stable environmentally friendly PSCs through low-dimensional engineering.

Morphology evolution of ultra-stable and low-cost all-inorganic lead-free perovskite solar cells

The emergence of all-inorganic lead-based perovskite solar cells (PSCs) has generated enormous interest in the perovskite research community. The presence of lead (Pb) in these devices, however, has caused some challenges because of its high toxicity, which slows down or even hinders their commercialization. Here we report the successful fabrication of all-inorganic Pb-free PSCs with environment-friendliness, low cost, and excellent stability. In such devices, novel Cs3Sb2I9 perovskite films were prepared by a solution-based method, which possess high-quality morphology, long carrier lifetime, low defect density, and a well-matched band structure with other functional layers. Additionally, carbon electrodes were introduced to replace the labile organic components and expensive noble metal electrodes commonly seen in the traditional PSCs. As a result, the all-inorganic Pb-free PSCs exhibit a champion PCE of 1.43%, which is more than two times higher than the results from previous reports. More importantly, the all-inorganic Pb-free PSCs demonstrated excellent stability under various extreme conditions, such as constant illumination, high humidity, and high temperature. This study provides very useful insights into the development of next-generation commercial PSCs with environment-friendliness, low cost, and excellent stability.

A fluorescent sensor to detect lead leakage from perovskite solar cells.

Hybrid perovskites have been considered a hot material in the semiconductor industry; included as an active layer in advanced devices, from light emitting applications to solar cells, where they lead as a new strategic solution, they promise to be the next generation high impact class of materials. However, the presence - in most cases - of lead in their matrix, or lead byproducts as a consequence of material degradation, such as PbI2, is currently hindering their massive deployment. Here, we develop a fluorescent organic sensor (FS) based on the Pb-selective BODIPY fluorophore that emits when the analyte - lead in this case - is detected. We carried out a fluorimetric analysis to quantify the trace concentration of Pb2+ released from lead-based perovskite solar cells, exploring different material compositions. In particular, we immersed the devices in rainwater, to simulate the behavior of the devices under atmospheric conditions when the sealing is damaged. The sensor is studied in a phosphate buffer solution (PBS) at pH 4.5 to simulate the pH of acidic rain, and the results obtained are compared with ICP-OES measurements. We found that with fluorometric analysis, lead concentration could be calculated with a detection limit as low as 5 μg l-1, in agreement with ICP-OES analysis. In addition, we investigated the possibility of using the sensor on a solid substrate for direct visualization to determine the presence of Pb. This can constitute the base for the development of a Pb-based label that can switch on if lead is detected, alerting any possible leakage.