Organic-inorganic Perovskite Solar Cells Research Articles

Maximizing photovoltaic performance of all-inorganic perovskite CsSnI3-xBrx solar cells through bandgap grading and material design

In the modern era of technology, worldwide paradigms have been shifted toward the utilization of green energy. Sun energy is the most astonishing eco-friendly resource of energy and can be harnessed with the help of photovoltaic cells. Hybrid (Organic-Inorganic) perovskite solar cells (PSCs) are emerged with incredible photovoltaic (PV) performance. Nevertheless, a significant challenge lies in their lower stability under diverse environmental conditions. To deal with this challenge, all inorganic cesium-based PSC has been studied and analyzed, results improved stability in comparison to hybrid PSC. However, the noxious nature of lead is deleterious to the environment. So, this work primarily aimed, to study lead-free all inorganic tin-based perovskite compound CsSnI3-xBrx, as the main light absorber layer. Further, to elevate the PV performance of PSC, bandgap grading is performed on CsSnI3-xBrx by varying bromide concentration x from 0 to 3. Bandgap grading encourages the absorption of a wide range of the light spectrum, by modulating bandgap (Eg) / affinity(χ) through the distance of the CsSnI3-xBrx layer. Additionally, it enhances light-generated charge carrier separation and collection by end electrodes. In this work, two different strategies have been adopted, linear and parabolic. During linear grading, the impact of variation in x (0 to 3) has been analyzed over the thickness 50–––500 nm in 10 linear steps for CsSnI3-xBrx. The highest PCE fetched from linearly graded layered FTO / CeO2 / CsSnI3-xBrx / CFTS / Gold PSC is 21.68 %. Similarly, in the parabolic graded absorber layer, the influence of change in the bowing factor (0 to 1), has been analyzed relative to different values of x (0 to 3). With improvement in PV performance, the maximum PCE delivered by parabolic-graded PSC is 23.61 %. Additionally, this work extends to check the compatibility of distinct electron transport layers (ETLs) and hole transport layers (HTLs). Upon analysis, it has been found that the best PV performance was obtained while selecting SnO2 / PEDOT as ETL / HTL respectively.

Elucidating Interfacial Hole Extraction and Recombination Kinetics in Perovskite Thin Films

Hybrid organic–inorganic perovskite solar cells (PSCs) are receiving huge attention owing to their marvelous advantages, such as low cost, high efficiency, and superior optoelectronics characteristics. Despite their promising potential, charge-carrier dynamics at the interfaces are still ambiguous, causing carrier recombination and hindering carrier transport, thus lowering the open-circuit voltages (Voc) of PSCs. To unveil this ambiguous phenomenon, we intensively performed various optoelectronic measurements to investigate the impact of interfacial charge-carrier dynamics of PSCs under various light intensities. This is because the charge density can exhibit different mobility and charge transport properties depending on the characteristics of the charge transport layers. We explored the influence of the hole transport layer (HTL) by investigating charge transport properties using photoluminescence (PL) and time-resolved (TRPL) to unveil interfacial recombination phenomena and optoelectronic characteristics. We specifically investigated the impact of various thicknesses of HTLs, such as 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD), and poly(triaryl)amine (PTAA), on FA0.83MA0.17Pb(Br0.05I0.95)3 perovskite films. The HTLs are coated on perovskite film by altering the HTL’s concentration and using F4-TCNQ and 4-tert-butylpyridine (tBP) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) as dopants both for spiro-OMeTAD and PTAA. These HTLs diversified the charge concentration gradients in the absorption layer, thus leading to different recombination rates based on the employed laser intensities. At the same time, the generated charge carriers are rapidly transferred to the interface of the HTL/absorption layer and accumulate holes at the interface because of inefficient capacitance and mobility differences caused by differently doped HTL thicknesses. Notably, the charge concentration gradient is low at lower light intensities and did not accumulate holes at the HTL/absorption layer interface, even though they have high charge mobility. Therefore, this study highlights the importance of interfacial charge recombination and charge transport phenomena to achieve highly efficient and stable PSCs.

Ab-initio study of hybrid perovskites Cs2AgGaCl6 for solar cells applications

Double perovskites have garnered significant attention for use in renewable energy applications, particularly solar cells. The development of organic-inorganic hybrid halide perovskite solar cells has advanced rapidly over the last ten years. In this article, fundamental aspects of transport properties of Cs2AgGaCl6 have been illustrated using DFT-based simulation. Constantly is covered that the calculated lattice constant agreed with the available experimental data. With an indirect band gap, the electronic profile demonstrates a semiconducting nature. Reporting bandgap of 1.20 eV for Cs2AgGaCl6. This bandgap remains suitable for solar cell semiconductors. The computed values of effective masses reveal that effective masses of holes are greater than those of electrons. Further various optical parameters have also been examined. The absorption of light in the visible and ultraviolet spectrums is guaranteed by the absorption bands 2.7–4.2 eV and 3.5–4.5 eV. We believe that such insights offer a new starting point and a framework for future research. So, knowledge and drive gained from these studies will stimulate more theoretical investigation into novel perovskite-based materials with novel applications.

Design and Optimization of Plasmonic Nanoparticles-Enhanced Perovskite Solar Cells Using the FDTD Method.

This study explores how plasmonic nanoparticles affect absorption, transmission, and reflection—three important performance metrics in organic-inorganic halide perovskite solar cells (PSCs). Through an investigation of different types of nanoparticles and their concentration in the composite layer, the study provides important information for improving PSC design in order to increase overall efficiency. The results highlight the importance of the type and volume fraction of nanoparticles in the composite layer, which influence the spectral characteristics of the solar cell, such as absorption, reflection, and transmission. These findings could encourage PSCs to be widely used as a practical and affordable renewable energy source, which would advance the development of affordable and efficient solar energy technologies.

Unraveling Interface-Driven and Loss Mechanism-Centric Phenomena in 3D/2D Halide Perovskites: Prospects for Optoelectronic Applications.

In recent years, organic-inorganic metal halide perovskite solar cells (PSCs) have attracted considerable interest due to their remarkable and rapidly advancing efficiencies. Over the past decade, PSC efficiencies have significantly approached those of state-of-the-art silicon-based photovoltaics, making them a promising material. Currently, the scientific community widely recognizes the performance of 3D-PSCs and 2D-PSCs individually. However, when both are combined to form a heterostructure, the lattice and charge dynamics at the interface undergo a multitude of mechanisms that affect their performance. The interface between heterostructures facilitates the degradation of PSCs. The degradation pathways can be attributed to lattice distortions, inhomogeneous energy landscapes, interlayer ion migration, nonradiative recombination, and charge accumulation. This Review is dedicated to examining the phenomena that arise at the interface of 3D/2D halide perovskites and their related photophysical properties and loss mechanism processes. We mainly focus on the impact of lattice mismatch, energy level alignment, anomalous carrier dynamics, and loss mechanisms. We propose a "cause-impact-identify-rectify" approach to gain a comprehensive understanding of the ultrafast processes occurring within the material. Finally, we highlight the importance of advanced spectroscopic and imaging techniques in unraveling these intricate mechanisms. This discussion delves into the future possibilities of fabricating 3D/2D heterostructure-based optoelectronic devices, pushing the boundaries of performance across diverse fields. It envisions the creation of devices with unparalleled capabilities, exceeding the limitations of current technologies.

Thermal Analysis of a Plasmonic Perovskite Solar Cell: Using Coupled Opto-Electro-Thermal (OET) Modeling

Organic-inorganic heterojunction perovskite solar cells (PSCs) are of high interest due to their low manufacturing cost and higher power conversion efficiency (PCE). Hence, we study the opto-electro-thermal (OET) characteristics and investigate the optical and carrier transport and thermodynamic behaviors on the PSC. In this research, optical and electrical coupled behavior is investigated, and the results of this simulation are in the optimal state for nanoparticles (NPs) with a diameter of 50 nm: the short-circuit current (Jsc) of 18.05 mA/cm2, the open-circuit voltage (Voc) of 0.9406 V, and PCE of 14.15% were obtained. Then, by adding thermal behavior to optical and electrical physics, thermal effects and power losses in the solar cell were obtained. In this case, 221.5 W/m2 Joule heat, 154 W/m2 thermal heat, 123 W/m2 Peltier heat, and 92.3 W/m2 nonradiative heat waste power were achieved. Under these losses, the electrical parameters decrease. The parameters are Jsc=21.74 mA/cm2, Voc=0.94 V, and PCE=13.53%. The best case is obtained for the structure without NPs.

Progress on Electron Transport Layers for Perovskite Solar Cells

The photovoltaic industry is very interested in designing and developing next-generation device architectures using organic-inorganic perovskite hybrid solar cell materials. In fact, perovskites represent one of the most promising materials for high efficiency, low-cost solar cells. This is most apparent in the power conversion efficiency of perovskite solar cells (PSCs) going from 3.8 to 24.2 % in recent years. One of the primary challenges of developing PSC’s however is the realization of an appropriate electron transport layer. As such, this review focuses on recent developments in the electron transport layer (ETL) of perovskite solar cells. It examines and summarises designs, electron transport layers and perovskite active layers for efficient perovskite solar cells. The performance and stability issues with organic-inorganic halide perovskite solar cells are also discussed with some recommendations for additional research on the ETL and perovskite active layer were offered.

Recent developments in perovskite materials, fabrication techniques, band gap engineering, and the stability of perovskite solar cells

Organic-inorganic hybrid metal halide perovskite solar cells (PSC) represent a novel class of optoelectronic semiconductors that have garnered significant attention from photovoltaic researchers globally. This is due to their continually improving efficiency, straightforward solution processing methods, use of lightweight and cost-effective materials, and other notable features. The advantageous properties of perovskite materials, such as superior charge transport, tunable band gap, and distinctive electronic structure, contribute to their appeal. Over the past 6 to 7 years, diverse device architectures and fabrication techniques for PSC have emerged, achieving an impressive power conversion efficiency (PCE) of 25.7%. This review article primarily focuses on recent advancements in PSC fabrication techniques, synthesis, device architecture, charge transport mechanisms, band gap engineering, and stability. Additionally, it provides a summary of recently reported materials used in various layers of PSC, including the perovskite layer, as well as electron and hole transport layers. Lastly, the article outlines the challenges faced in the development of PSC, offers recommendations, and suggests potential directions for future research to guide the field forward.

A Different, Nondestructive Method of Investigating In Situ Degradation in Hybrid Perovskite Solar Cells

One of the most significant impediments to the upscaling of hybrid organic-inorganic perovskite (HOIP) solar cells is poor stability. So, to effectively establish precautionary strategies, it is necessary to have a comprehensive grasp of the mechanisms that contribute to their degradation. Conventional characterization techniques used for in situ degradation assessment of perovskite solar cells either track just universal parameters, which yields poor insights about localized degradation processes, or the technique itself induces degradation, which may confound results. Developed in this study is a nondestructive technique of analyzing in situ active layer degradation in HOIP solar cells’ active layer utilizing a combination of optical modelling and ageing device’s reflectance tracking. The optical dielectric functions of the solar cell’s functional layers were modelled using the layers’ transmitted and reflected light spectra. The transfer matrix approach was used to fit the reflectance spectrum of entire solar cell layer stacks utilizing the computed dielectric functions for individual materials and accounting for the possibility of lead iodide gradient layer formation in the model. Leveraging no other characterization method, the presence of a lead iodide gradient layer was identified within the solar cell layer stack, an unmistakable indicator of methyl ammonium lead iodide perovskite (MAPI) degradation, probing with only photons.

3-Thiophenemalonic Acid Additive Enhanced Performance in Perovskite Solar Cells.

The development of ambient-air-processable organic-inorganic halide perovskite solar cells (OIHPSCs) is a challenge necessary for the transfer of laboratory-scale technology to large-scale and low-cost manufacturing of such devices. Different approaches like additives, antisolvents, composition engineering, and different deposition techniques have been employed to improve the morphology of the perovskite films. Additives that can form Lewis acid-base adducts are known to minimize extrinsic impacts that trigger defects in ambient air. In this work, we used the 3-thiophenemalonic acid (3-TMA) additive, which possesses thiol and carboxyl functional groups, to convert PbI2, PbCl2, and CH3NH3I to CH3NH3PbI3 completely. This strategy is effective in regulating the kinetics of crystallization and improving the crystallinity of the light-absorbing layer under high relative humidity (RH) conditions (30-50%). As a result, the 3-TMA additive increases the yield of the power conversion efficiency (PCE) from 14.9 to 16.5% and its stability under the maximum power point. Finally, we found that the results of this work are highly relevant and provide additional inputs to the ongoing research progress related to additive engineering as one of the efficient strategies to reduce parasitic recombination and enhance the stability of inverted OIHPSCs in ambient environment processing.

Crystallization control of wide-bandgap perovskites for efficient solar cells via adding an anti-solvent into the perovskite precursor.

Organic-inorganic halide-based wide-bandgap perovskite solar cells (PSCs) have been researched extensively due to their potential application in tandem solar cells. In this study, we directly added an anti-solvent (diethyl ether, DE) into the perovskite precursor for controlling the crystallization process of perovskite layers with a wide bandgap (1.74 eV). The introduction of DE could facilitate the nucleation and accelerate the perovskite growth during the spin-coating process. Due to the improved crystallization of the perovskite, the wide-bandgap PSCs showed a high power-conversion efficiency (PCE) of 19.7% on average with improved current density and fill factor. In contrast, the control devices without using DE exhibited a low average PCE of 17.6%. Moreover, the ambient stability of the related PSCs was simultaneously enhanced with a remarkably decreased PCE degradation, from 31.3% to 16.8%, after 16 days of storage and measurement. The DE-assisted well-crystallized PSCs showed a highest PCE of 20.1%, with a stable current output and negligible hysteresis. Our research provides a simple and effective way for controlling the crystallization of wide-bandgap perovskite layers and hence improving the performance of wide-bandgap PSCs.

Preparation of two-dimensional perovskite layer by solution method for improving stability of FAPbI<sub>3</sub> perovskite solar cells

Organic-inorganic metal halide perovskite solar cells (PSCs) have been widely studied due to their excellent photoelectric conversion performance, but the inherent chemical instability of CH(NH<sub>2</sub>)<sub>2</sub>PbI<sub>3</sub> (FAPbI<sub>3</sub>) hinders its sustainable development. In particular, the surface interface of the membrane has prominent humidity sensitivity due to lower activation energy, the defect of the surface interface has a strong correlation with the film stability, and the treatment result of the defect is one of the key factors to improve the long-term stability. The FAPbI<sub>3</sub> suffers phase transition from black perovskite phase to yellow non-perovskite phase at room temperature, and the moisture will accelerate this phase transition. Interface engineering is one of the common methods to improve the stability of perovskite solar cells. In addition to interface engineering, there is a strategy of stacking a two-dimensional (2D) perovskite layer on the surface for interface passivation. However, most of the preparation methods of 2D perovskite layer have limitations. In this work, the full solution method and post-treatment mode of annealing are adopted, the hybrid perovskite solar cells of vitamin perovskite are successfully fabricated. The FAPbI<sub>3</sub> perovskite surface is uniformly spin-coated with butylamine iodide (BAI) solution, and the formation of 2D perovskite is driven on the surface of FAPbI<sub>3</sub> perovskite. Due to the passivation of surface interface defects by the 2D perovskite layer, the non-radiative recombination of charge carriers is reduced, greatly improving the carrier lifetime. Because of the hydrophobicity of long chain molecules in 2D perovskite, the long-term stability of the device is significantly improved. Consequently, the unencapsulated device containing 2D perovskite layer remains above 80% after operating at room temperature in ambient air with a relative humidity (RH) of 60% for nearly 1000 hours. The 2D perovskite layer can significantly improve the long-term stability of the film without affecting the charge carrier transport performance. This method of improving the stability of the device by constructing 2D perovskite layer is in line with the requirements and development trend of high-quality perovskite solar cells, and is a strategy with great development potential.

An amorphous MgF2 anti-reflective thin film for enhanced performance of inverted organic-inorganic perovskite solar cells.

The effective control of light plays an important role in optoelectronic devices. However, the effect of anti-reflection thin film (ARTF) in inverted perovskite solar cells (PSCs) (p-i-n) has so far remained elusive. Herein, MgF2 ARTF with different thicknesses (approximately 100, 330, and 560 nm) were deposited on the glass side of FTO conductive glass substrates by vacuum thermal evaporation. The results of reflectance and transmittance spectroscopy show that approximately 330 nm MgF2 ARTF can reduce reflectivity and increase transmittance on FTO conductive glass substrates. The results of SEM, XRD, and AFM show that the surface of amorphous MgF2 ARTF possesses a lot of nanoscale pits. The effect of the MgF2 ARTF on the performance of inverted perovskite solar cells (PSCs) (p-i-n) was investigated. The power conversion efficiencies (PCE) of inverted PSCs without and with MgF2 ARTF are 18.20 and 21.28%, respectively. The significant improvement in PCE of the devices with MgF2 ARTF is caused by the improvement in short-circuit current density. The stability results of the devices show that the PCE remains above 70% of the initial PCE after 300 h illumination.

Recent Developments in Atomic Layer Deposition of Functional Overlayers in Perovskite Solar Cells.

Over the last decade, research in organic-inorganic lead halide perovskite solar cells (PSCs) has gathered unprecedented momentum, putting the technology on the brink of full-scale commercialization. A wide range of strategies have been implemented for enhancing the power conversion efficiency of devices and modules, as well as improving stability toward high levels of irradiation, temperature, and humidity. Another key element in the path to commercialization is the scalability of device manufacturing, which requires large-scale deposition of conformal layers without compromising the delicate structure of the perovskite film. In this context, atomic layer deposition (ALD) tools excel in depositing high-quality conformal films with precise control of film composition and thickness over large areas at relatively low processing temperatures. In this commentary, we will briefly outline recent progress in PSC technology enabled by ALD tools, focusing on layers deposited above the absorber layer. These interlayers include charge transport layers, passivation layers, buffer layers, and encapsulation techniques. Additionally, we will discuss some of the challenges and potential avenues for research in PSC technology underpinned by ALD tools.

Efficient laboratory perovskite solar cell recycling with a one-step chemical treatment and recovery of ITO-coated glass substrates

The proliferation of organic–inorganic perovskite solar cells (PSCs) has garnered considerable attention due to their potential for low-cost, large-scale photovoltaic panel production. However, the inclusion of lead in PSCs poses significant sustainability challenges, necessitating effective end-of-life treatment strategies to mitigate environmental pollution and comply with electronic waste disposal regulations. In this study, we present a novel recycling system for decomposing and reclaiming the constituent materials of a typical PSC. Utilizing a one-step solution process extraction approach, we successfully preserved the chemical composition of each layer, enabling their potential reuse. This recycling method not only addresses the separation of the toxic lead component but also emphasizes the recovery of other valuable PSC layers. Notably, the commonly used hole transport layer in perovskite solar cells is Spiro-OMeTAD, which was successfully extracted with chlorobenzene, with its purity subsequently confirmed. Moreover, the removal of individual layers facilitated the retrieval of indium-doped tin oxide (ITO) conductive glass, a critical substrate in PSC fabrication. Comparative analysis of the physical and electrical properties of recycled and reference ITO substrates revealed minimal discrepancies, indicating the feasibility of reusing recycled substrates without compromising device performance. The proposed recycling technique offers a practical approach to mitigate pollution risks, minimize waste generation during the recycling process of perovskite-based solar cells, and reduce end-of-life recycling costs.

Improving the Conductivity of Amide-Based Small Molecules through Enhanced Molecular Packing and Their Application as Hole Transport Mediators in Perovskite Solar Cells.

Organic-inorganic hybrid halide perovskite solar cells (PSCs) have attracted substantial attention from the photovoltaic research community, with the power conversion efficiency (PCE) already exceeding 26%. Current state-of-the-art devices rely on Spiro-OMeTAD as the hole-transporting material (HTM); however, Spiro-OMeTAD is costly due to its complicated synthesis and expensive product purification, while its low conductivity ultimately limits the achievable device efficiency. In this work, we build upon our recently introduced family of low-cost amide-based small molecules and introduce a molecule (termed TPABT) that results in high conductivity values (∼10-5 S cm-1 upon addition of standard ionic additives), outperforming our previous amide-based material (EDOT-Amide-TPA, ∼10-6 S cm-1) while only costing an estimated $5/g. We ascribe the increased optoelectronic properties to favorable molecular packing, as shown by single-crystal X-ray diffraction, which results in close spacing between the triphenylamine blocks. This, in turn, results in a short hole-hopping distance between molecules and therefore good mobility and conductivity. In addition, TPABT exhibits a higher bandgap and is as a result more transparent in the visible range of the solar spectrum, leading to lower parasitic absorption losses than Spiro-OMeTAD, and has increased moisture stability. We applied the molecule in perovskite solar cells and obtained good efficiency values in the ∼15% range. Our approach shows that engineering better molecular packing may be the key to developing high-efficiency, low-cost HTMs for perovskite solar cells.

Investigation on buried interfacial charge carrier dynamics of the MAPbI3/NiO interface by mismatch strain and termination

Organic-inorganic halide perovskite solar cells (PSCs) have attracted significant attention due to their low cost, simple fabrication process, and rapid improvement in photovoltaic performance. NiO is often considered as a potential hole transport layer (HTL) in these PSCs owing to its wide band gap and deep valence band level. However, uncertainties remain regarding the interfacial charge carrier dynamics at the perovskite/HTL interface induced by the interfacial mismatch strain and terminal configuration. Herein, typical MAPbI3/NiO interfacial terminal configurations (MAI-Ni, MAI-O, PbI-Ni, PbI-O) with strain-configured interfaces were explored by first-principle and device simulation. The results indicate that the binding energy decreases, the carrier transport efficiency increases, and the valence band offset (VBO) decreases as the interfacial atomic configuration of the perovskite surface changes from MAI to PbI. Meanwhile, the compressive strain applied on the perovskite surface also increases the interfacial VBO. The J-V curves and energy band of the PSCs show that the device performance tends to enhance first and then decrease as the positive VBO of the MAPbI3/NiO interface increases. Thus, the strain and termination configuration could modulate the device's photovoltaic performance, which is dependent on the energy band bending caused by the strain and termination configuration. This work provides a valuable understanding of the MAPbI3/NiO interface and contributes new strategies to interface optimization for further improving the photoelectric conversion efficiency of PSCs.

Phase Stability Improvement of a γ-CsPbI3 Perovskite Solar Cell Utilizing a Barium Bis(trifluoromethanesulfonimide) Solution.

The cesium lead iodide (CsPbI3) perovskite solar cell possesses a wide band gap ranging from 1.65 to 1.75 eV, which is suitable for integration into a tandem structure along with a low-band-gap silicon solar cell. Moreover, CsPbI3 has received considerable attention as a potential solution for the prevalent issues of low thermal stability of organic-inorganic perovskite solar cells and phase segregation encountered in conventional mixed halide wide-band-gap perovskite solar cells. Through the implementation of volatile additives, CsPbI3 has demonstrated substantial advancements in efficiency, process temperature, and stability. This study introduces a novel approach for barium (Ba)-doping by spraying an antisolvent containing barium bis(trifluoromethanesulfonimide) during the spin-coating process. By incorporating Ba2+ through this spraying technique, the formation of the delta phase in CsPbI3 is significantly suppressed; thereby, a power conversion efficiency of 18.56% is achieved, and a remarkable 93% of the initial efficiency is maintained after 600 h.

Design and numerical modeling of environmentally compatible HTL-free organic-inorganic perovskite solar cells

Environment-friendly tin-based perovskite solar cells have gained much research interest because of the non-toxic nature of tin. The broader visible absorption spectrum of methylammonium tin iodide and smaller band-gap value of 1.3 eV have made methylammonium tin iodide viable to be used as an absorber layer in place of methylammonium lead iodide having toxic lead as its central element. Lead being water soluble is hazardous for the environment and human health, when a panel breaks or gets exposed to moisture. In this study, hole transport layer (HTL) free and lead-free, tin-based perovskite solar cell with layered structure as Glass/TCO/WS2/CH3NH3SnI3/back-contact, and its variant is proposed and investigated. To realize an optimum set of performance parameters, extensive investigations are carried out by considering two variants of the proposed design viz. lead-free absorber PSC (LF-PSC) and lead-free absorber optimized PSC (LFO-PSC). The impact of varying defect density and position of defects in bulk and at the interface on the performance of PSC is investigated and optimized. Changing defect density of the absorber layer shows a direct influence on diffusion length and the lifetime of charge carriers. Performance evaluation parameters of the LFO-PSC obtained in this study are Voc= 1.024 V, Jsc= 33.33 mA/cm2, FF= 80.13%, PCE= 27.33%. Higher efficiency is attributed to the presence of a single WS2/MASnI3 interface and therefore reduced recombination of charge carriers. PCE of optimized lead-free absorber PSC has been reported to be 8.9% higher than its basic variant i.e. LF-PSC design. The influence of defect levels, back reflecting coating and metal work function of back contact on the performance of PSC is investigated. Recombination curves are also studied to understand the impact of defects on the proposed PSC structure.

Optimized Doping of Diffusion Blocking Layers and Their Impact on the Performance of Perovskite Photovoltaics.

The roll-to-roll printing production process for hybrid organic-inorganic perovskite solar cells (PSCs) demands thick and high-performance solution-based diffusion blocking layers. Inverted (p-i-n) PSCs usually incorporate solution-processed PC70BM as the electron-transporting layer (ETL), which offers good electron charge extraction and passivation of the perovskite active layer grain boundaries. Thick fullerene diffusion blocking layers could benefit the long-term lifetime performance of inverted PSCs. However, the low conductivity of PC70BM significantly limits the thickness of the PC70BM buffer layer for optimized PSC performance. In this work, we show that by applying just enough N-DMBI doping principle, we can maintain the power conversion efficiency (PCE) of inverted PSCs with a thick (200 nm) PC70BM diffusion blocking layer. To better understand the origin of an optimal doping level, we combined the experimental results with simulations adapted to the PSCs reported here. Importantly, just enough 0.3% wt N-DMBI-doped 200 nm PC70BM diffusion blocking layer-based inverted PCSs retain a high thermal stability at 60 °C of up to 1000 h without sacrificing their PCE photovoltaic parameters.