Efficient Perovskite Solar Cells Research Articles

Simulation and optimization of triple cation perovskite solar cell using SCAPS-1D

Triple cation (Csx(MA0.17FA0.83)1-xPb(I0.83Br0.17)3) perovskites have attracted extensive attention owing to their excellent stability and photovoltaic performance. In this work, an efficient perovskite solar cell with a structure of TiO2/Csx(MA0.17FA0.83)1-xPb(I0.83Br0.17)3 (CsFAMA)/CuSCN was proposed and optimized theoretically using the solar cell simulator capacitance software (SCAPS-1D). This study optimized the parameters of the absorber layer, such as the thickness, doping density, defect density and bandgap. In addition, the electron transport layer (ETL) and the hole transport layer (HTL) are optimized by varying their electron affinity, thickness and doping density. It was found that the optimization of the absorber layer thickness and doping density provided a significant improvement in the efficiency of the device, while the parameters of both ETL and HTL showed minor influence on the device performance. Moreover, the operation temperature was discussed to provide further insight concerning the device performance. It showed that an increase of the operation temperature from 300 to 700 K resulted in reduction of device performance. And the CsFAMA-based device showed the highest power conversion efficiency (PCE) of 28.66% at 300 K with fill factor (FF) of 83.18%, open circuit voltage (Voc) of 1.48 V and short circuit current density (Jsc) of 23.27 mA/cm2. The optimized values of the absorber thickness, defect density and doping density were found to be 500 nm, 2.6 × 1013 cm−3 and 1 × 1016 cm−3, respectively. The findings of this study suggest CsFAMA-based absorber materials can play an important role in high efficiency perovskite solar cells with excellent stability.

High efficiency and stability of perovskite solar cells prepared by alkali metal interfacial modification

High efficiency and stability of perovskite solar cells prepared by alkali metal interfacial modification

Improved performance of inorganic CsPbI3 perovskite solar cells with WO3/C60 UTL bilayer as an ETL structure: a computational study

CsPbI3, also known as cesium lead iodide, has garnered significant attention as a potential absorber in perovskite solar cells (PSCs). CsPbI3-PSCs have not matched the high performance of hybrid PSCs. This study aimed to identify an effective combination of charge transport layers. Six-hole transporting layers (HTLs) including Spiro-OMeTAD, Cu2O, CuO, CuAlO2, CuSbS2, and SrCu2O2, as well as five electron transporting layers (ETLs) such as TiO2, WO3, ZnO, IGZO, and CdZnS, were tested separately in 30 PSCs. The findings of this research indicate that CuAlO2 as the HTL and WO3 as the ETL that are the most appropriate materials among the options examined, so we use FTO/WO3/CsPbI3/CuAlO2/Au as a required PSC. In this research, we used SCAPS (Solar Cell Capacitance Simulator)−1D device modeling to investigate the bilayer ETL of inorganic CsPbI3-PSC and discover the methods to improve their efficiency. In planar PSCs, optimizing electron–hole pair extraction and recombination at the ETL/perovskite interface is crucial for achieving high performance. The key concept is to enhance the WO3/perovskite interface properties by adding a 5 nm ultra-thin layer (UTL) of C60. The bilayer structure WO3/C60 was found to have the advantage of high electron extraction and low interfacial recombination, primarily due to more effective energy level alignment and defect passivation. To achieve the superior efficiency of PSC, various factors such as defect and doping densities in all layers, the energy level alteration of ETL and HTL, interface defect densities on both ETL and HTL sides, back metal contact, operating temperature, and parasitic resistances were optimized. After optimizing these parameters, the efficiency of the system containing WO3/C60 bilayer ETL was found to be 29.39%. The current work proposes a straightforward and promising method to create photovoltaic devices, especially for many types of perovskites, with desirable charge transport layers and recombination properties.

Recent Advances in Carbon Nanotube Utilization in Perovskite Solar Cells: A Review

Due to their exceptional optoelectronic properties, halide perovskites have emerged as prominent materials for the light-absorbing layer in various optoelectronic devices. However, to increase device performance for wider adoption, it is essential to find innovative solutions. One promising solution is incorporating carbon nanotubes (CNTs), which have shown remarkable versatility and efficacy. In these devices, CNTs serve multiple functions, including providing conducting substrates and electrodes and improving charge extraction and transport. The next iteration of photovoltaic devices, metal halide perovskite solar cells (PSCs), holds immense promise. Despite significant progress, achieving optimal efficiency, stability, and affordability simultaneously remains a challenge, and overcoming these obstacles requires the development of novel materials known as CNTs, which, owing to their remarkable electrical, optical, and mechanical properties, have garnered considerable attention as potential materials for highly efficient PSCs. Incorporating CNTs into perovskite solar cells offers versatility, enabling improvements in device performance and longevity while catering to diverse applications. This article provides an in-depth exploration of recent advancements in carbon nanotube technology and its integration into perovskite solar cells, serving as transparent conductive electrodes, charge transporters, interlayers, hole-transporting materials, and back electrodes. Additionally, we highlighted key challenges and offered insights for future enhancements in perovskite solar cells leveraging CNTs.

Elevated Efficiency and Stability of Hole-Transport-Layer-Free Perovskite Solar Cells Triggered by Surface Engineering.

Surface engineering is one of the important strategies to enhance the power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). Herein, 2-chloro-1,3-dimethylimidazolidinium hexafluorophosphate (CIP) was introduced into PSCs to passivate the defects of the perovskite films. There are many F atoms in CIP molecules that have strong electronegativity and hydrophobicity. F groups can interact with Pb2+ defects, inhibit interface recombination, improve the interaction between the CIP ionic liquid and perovskite film, and reduce the defect density of perovskites, thus improving the stability of perovskite devices. Density functional theory calculation reveals that CIP can interact with uncoordinated Pb2+ in perovskites through coordination, reduce the defects of perovskite films, and inhibit nonradiation recombination. The ITO/SnO2/MAPbI3/CIP/carbon devices without hole transport layers possessed the highest PCE of 17.06%. Moreover, the unencapsulated device remains at 98.18% of the initial efficiency stored in 30-40% relative humidity for 850 h. This strategy provides an effective reference for enhancing the performance of PSCs.

Enhancing Efficiency and Stability in Carbon-Based Perovskite Solar Cells by Double Passivation with Ultralow-Cost Coal-Derived Graphene and Its Derivatives.

Coal-derived carbon nanomaterials possess numerous superior features compared to other classic carbon, such as readily accessible surfaces, tunable pore structure, and facile and precise surface functionalization. Therefore, the controllable preparation of coal-derived carbon nanomaterials is anticipated to be of great significance for the performance improvement and commercialization process of carbon-based perovskite solar cells (C-PSCs). In this study, we successfully synthesized highly stable and commercially valuable graphene oxide (GO) and reduced graphene oxide (rGO) utilizing coal. Compared to traditional methods and commercial graphene, the chemical oxidation and pyrolysis process used in this study is mild and simple, offering the advantages of controlled composition and the absence of other impurities. GO or rGO was incorporated into the top of the SnO2 electron transport layer (ETL) of C-PSCs. Under optimized conditions and ultraviolet-ozone (UVO) irradiation, the ultimate power conversion efficiency (PCE) increased from the unmodified 12.4 to 14.04% (based on rGO) and 15.18% (based on GO), representing improvements of 22 and 31%, respectively. The improved photovoltaic performance is mainly owing to enhanced charge transport capabilities, denser interfacial contacts, improved carrier separation properties, increased conductivity, and abundance of hydrophilic functional groups in GO, which can form more stable hydrogen bonds with SnO2. After being stored at room temperature and ambient humidity for 30 days, the modified, unpacked devices retained 87% of the highest power conversion efficiency (PCE). This study introduces a practical and manageable method to enhance the performance of C-PSCs by using functional carbon nanomaterials derived from coal.

Interfacial Modification of NiOx for Highly Efficient and Stable Inverted Perovskite Solar Cells

AbstractNickel oxide is one of the most promising hole‐transporting materials in inverted perovskite solar cells (PSCs) but suffers from undesired reactions with perovskite which leads to limited device performance and stability. Self‐assembled monolayers (SAMs) are demonstrated to effectively optimize the NiOx/perovskite interface, but the significance of the compactness of the SAM at the interface is less investigated. Here, a series of methoxy‐substituted triphenylamine functionalized benzothiadiazole (TBT) based SAM molecules, TBT‐BA, TBT‐FBA, and TBT‐DBA, with benzoic acid, 2‐fluorobenzoic acid and isophthalic acids as anchoring groups are used to modify NiOx. TBT‐BA with the simplest structure is demonstrated to form the densest SAM on NiOx, thus optimized NiOx/SAM/perovskite interface is achieved with enhanced charge collection and suppressed interfacial reaction and recombination. TBT‐BA can also passivate the perovskite most effectively due to the highest binding energy toward perovskite, thus the corresponding inverted PSCs show the highest PCE of 24.8% and maintain 88.7% of the initial PCE after storage at 60 °C for 2635 h in the glovebox. The work provides important insights into designing SAM molecules for modification transporting layers for efficient and stable PSCs.

Self‐Polymerized Spiro‐Type Interfacial Molecule toward Efficient and Stable Perovskite Solar Cells

AbstractIn the pursuit of highly efficient perovskite solar cells, spiro‐OMeTAD has demonstrated recorded power conversion efficiencies (PCEs), however, the stability issue remains one of the bottlenecks constraining its commercial development. In this study, we successfully synthesize a novel self‐polymerized spiro‐type interfacial molecule, termed v‐spiro. The linearly arranged molecule exhibits stronger intermolecular interactions and higher intrinsic hole mobility compared to spiro‐OMeTAD. Importantly, the vinyl groups in v‐spiro enable in situ polymerization, forming a polymeric protective layer on the perovskite film surface, which proves highly effective in suppressing moisture degradation and ion migration. Utilizing these advantages, poly‐v‐spiro‐based device achieves an outstanding efficiency of 24.54 %, with an enhanced open‐circuit voltage of 1.173 V and a fill factor of 81.11 %, owing to the reduced defect density, energy level alignment and efficient interfacial hole extraction. Furthermore, the operational stability of unencapsulated devices is significantly enhanced, maintaining initial efficiencies above 90 % even after 2000 hours under approximately 60 % humidity or 1250 hours under continuous AM 1.5G sunlight exposure. This work presents a comprehensive approach to achieving both high efficiency and long‐term stability in PSCs through innovative interfacial design.

Crystallization Regulation and Lead Leakage Prevention Simultaneously for High-Performance CsPbI2Br Perovskite Solar Cells.

All-inorganic CsPbI2Br perovskite is striking as a result of the reasonable band gap and thermal stability. However, the notorious air instability, unsatisfactory conversion efficiencies, and toxic water-soluble Pb2+ ions have greatly limited the further development of CsPbI2Br-based devices. Herein, a facile strategy is developed to prepare efficient and air-stable CsPbI2Br-based perovskite solar cells (PSCs) with in situ lead leakage protection. With the introduction of 2,2'-dihydroxy-4,4'-dimethoxy-5,5'-disulfobenzophenone disodium salt (BP-9) into the CsPbI2Br precursor solution, the crystallization of perovskite can be regulated at a reduced trap density, the uncoordinated Pb2+ ions and electron-rich defects in the structure can be passivated to suppress non-radiative recombination, and the energy level arrangement can be optimized to improve charge carrier transport. Consequently, the optimized PSC achieved a championship efficiency of 17.11%, accompanied by negligible J-V hysteresis and remarkably improved air stability. More importantly, the strong chelation of BP-9 with water-soluble Pb2+ ions minimizes the leakage of toxic lead in the perovskite structure.

Dual modification engineering enabled efficient perovskite solar cells with high open-voltage of 1.233 V

Interface engineering take as a crucial role in enhancing the performance of perovskite solar cells (PSCs). Here, we propose a comprehensive strategy to improve the performance and stability of PSCs through dual-interface modification approach. This strategy involves simultaneously introducing lead-free Cs3MnBr5: Ce3+ nanocrystals (NCs) between SnO2 electron transport layer and the perovskite layer, as well as 1H,1H-Perfluorooctylamine iodide (PFOAI) at the interface between perovskite and Spiro-OMeTAD hole transport layer. Firstly, we successfully prepare Cs3MnBr5: Ce3+ NCs, which exhibits an extensive ultraviolet response and effective blue photoluminescence. The photoluminescence quantum yield of Cs3MnBr5: Ce3+ NCs can reach 90 %, demonstrating efficient photon down-conversion ability and efficient defect passivation. Simultaneously, the organic halide salt PFOAI with super-hydrophobic properties efficiently passivates defects on the surface of perovskite and improves moisture-resistance of perovskite films. Taking advantage of these synergistic effects, we achieve efficient PSCs based the Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3 and Cs0.05(FA0.95MA0.05)0.95Pb(I0.95Br0.05)3 with power conversion efficiency (PCE) of 23.88 % and 24.24 %. We also achieved an ultrahigh open-circuit voltage (VOC) of 1.233 V, which represents one of the highest VOC values in a perovskite film with a bandgap of ∼1.60 eV. Additionally, the non-encapsulated double-interface modified PSCs exhibit long time, light and humidity stability. This study explores a novel and comprehensive strategy for manufacturing PSCs with high VOC, high PCE, and good stability.

Efficient Charge Transport in Inverted Perovskite Solar Cells via 2D/3D Ferroelectric Heterojunction.

While the 2D/3D heterojunction is an effective method to improve the power conversion efficiency (PCE) of perovskite solar cells (PSCs), carriers are often confined in the quantum wells (QWs) due to the unique structure of 2D perovskite, which makes the charge transport along the out-of-plane direction difficult. Here, a 2D/3D ferroelectric heterojunction formed by 4,4-difluoropiperidine hydrochloride (2FPD) in inverted PSCs is reported. The enriched 2D perovskite (2FPD)2PbI4 layer with n = 1 on the perovskite surface exhibits ferroelectric response and has oriented dipoles along the out-of-plane direction. The ferroelectricity of the oriented dipole layer facilitates the enhancement of the built-in electric field (1.06 V) and the delay of the cooling process of hot carriers, reflected in the high carrier temperature (above 1400 K) and the prolonged photobleach recovery time (139.85 fs, measured at bandgap), improving the out-of-plane conductivity. In addition, the alignment of energy levels is optimized and exciton binding energy (32.8 meV) is reduced by changing the dielectric environment of the surface. Finally, the 2FPD-treated PSCs achieve a PCE of 24.82% (certified: 24.38%) with the synergistic effect of ferroelectricity and defect passivation, while maintaining over 90% of their initial efficiency after 1000 h of maximum power point tracking.

Hexylammonium Acetate-Regulated Buried Interface for Efficient and Stable Perovskite Solar Cells

Due to current issues of energy-level mismatch and low transport efficiency in commonly used electron transport layers (ETLs), such as TiO2 and SnO2, finding a more effective method to passivate the ETL and perovskite interface has become an urgent matter. In this work, we integrated a new material, the ionic liquid (IL) hexylammonium acetate (HAAc), into the SnO2/perovskite interface to improve performance via the improvement of perovskite quality formed by the two-step method. The IL anions fill oxygen vacancy defects in SnO2, while the IL cations interact chemically with Pb2+ within the perovskite structure, reducing defects and optimizing the morphology of the perovskite film such that the energy levels of the ETL and perovskite become better matched. Consequently, the decrease in non-radiative recombination promotes enhanced electron transport efficiency. Utilizing HAAc, we successfully regulated the morphology and defect states of the perovskite layer, resulting in devices surpassing 24% efficiency. This research breakthrough not only introduces a novel material but also propels the utilization of ILs in enhancing the performance of perovskite photovoltaic systems using two-step synthesis.

Investigation of HTL-free perovskite solar cell under LED illumination: interplay between energy bandgap and absorber optimization

Abstract In this paper, we introduce an efficient perovskite solar cell (PSC) designed for indoor applications, which does not incorporate a hole transport layer (HTL). The perovskite material studied in this work is MAPbI3-xClx, whose bandgap energy can be adjusted to match the spectrum of white LEDs. While the removal of the HTL initially leads to a decline in cell performance, a subsequent enhancement is achieved in performance when the work function of the rear contact is increased. This improvement can be attributed to the increased electric field at the back contact interface. The performance of the HTL-free PSC is further optimized by adjusting various technological and physical factors of the perovskite absorber. These parameters include thickness, bulk defects, doping level, and energy gap of the perovskite material. Our results demonstrate that the HTL-free PSC structure exhibits superior performance metrics under a white LED environment at 1000 lux and a color temperature of 2700 K. In this context, a power conversion efficiency (PCE) above 34% can be obtained upon proper optimization procedures. Further, the interplay between the energy gap (Eg) of the absorber and the optimization procedures is investigated, highlighting its importance in the context of HTL-free designs for indoor applications. Practical recommendations stemming from this study include an emphasis on optimization for HTL-free cells and caution against applying ideal Eg ranges to non-optimized configurations.

Machine Learning Approach for Predicting the Hole Mobility of the Perovskite Solar Cells

AbstractTraditional computational approaches such as Monte Carlo simulation, molecular dynamics, and density functional theory (DFT) have contributed to understanding the role of hole mobility in the development of suitable hole transporting materials (HTMs) for perovskite solar cell efficiency. However, these methods often involve significant computational expenses, thereby limiting the number of feasible studies and hindering the extraction of valuable structure−property guidelines for a rational design of novel HTMs. To address these challenges, this study proposes an ultrafast predictive model that balances prediction accuracy and time efficiency, a critical aspect for predicting the hole mobility of HTMs for perovskite optimization. The model, which leverages the Random Forest learning algorithm, enables comprehensive and rapid analysis of photovoltaic features taken from previous experiments/literature and processed with the RDKit Python library. Notably, recognizing the challenges associated with high correlation in the dataset, a method to improve the calculation of feature importance in random forests is applied. The results highlight bertz_ct, chi1, and logP as key predictive features of HTM performance. However, the model underscores the need to uncover additional predictive features based on structure–property relationships to predict the optimized hole mobility. This approach significantly accelerates the discovery process, outperforming prevalent statistical methods in the prediction of hole mobility and HTM performance. This research signifies a pivotal step toward cost‐effective, accelerated stability and efficiency of HTMs, with implications for the advancement of optoelectronic devices.

Interlayer Carrier Dynamics in Two-Dimensional Perovskites Determined by the Length of Conjugated Organic Cations.

Unlocking the restricted interlayer carrier transfer in a two-dimensional perovskite is a crucial means to achieve the harmonization of efficiency and stability in perovskite solar cells. In this work, the effects of conjugated organic molecules on the interlayer carrier dynamics of 2D perovskites were investigated through nonadiabatic molecular dynamics simulations. We found that elongated conjugated organic cations contributed significantly to the accelerated interlayer carrier dynamics, originating from lowered transport barrier and boosted π-p coupling between organic and inorganic layers. Utilizing conjugated molecules of moderate length as spacer cations can yield both superior efficiency and exceptional stability simultaneously. However, conjugated chains that are too long lead to structural instability and stronger carrier recombination. The potential of conjugated chain-like molecules as spacer cations in 2D perovskites has been demonstrated in our work, offering valuable insights for the development of high-performance perovskite solar cells.

Dynamic Reversible Oxidation-Reduction of Iodide Ions for Operationally Stable Perovskite Solar Cells under ISOS-L-3 Protocol.

Despite rapid advancements in the photovoltaic efficiencies of perovskite solar cells (PSCs), their operational stability remains a significant challenge for commercialization. This instability mainly arises from light-induced halide ion migration and subsequent oxidation into iodine (I2). The situation is exacerbated when considering the heat effects at elevated temperatures, leading to the volatilization of I2 and resulting in irreversible device degradation. To the end, a thiol-contained reducing agent, mercaptoethylammonium iodide (ESAI), has been incorporated into the perovskite film. This addition aims to prevent the oxidation of iodide ions, thereby suppressing the light-induced degradation pathway of FAPbI3→FAI+PbI2. Additionally, the formation of a thiol-disulfide/I--I2 redox pair within the perovskite film provides a dynamic mechanism for the continuous reduction of I2 under light and thermal stresses, facilitating the healing of iodine-induced degradations. This approach significantly enhances the operational stability of PSCs. Under the ISOS-L-3 testing protocol (MPP tracking in an environment with relative humidity of ∼50% at ∼65°C), the treated PSCs maintain 97% of their original PCE after 300 hours of aging. In contrast, control devices exhibit almost complete degradation, primarily due to rapid thermal-induced I2 volatilization. These results demonstrate a promising strategy to overcome critical stability challenges in PSCs, particularly in scenarios involving thermal effects. This article is protected by copyright. All rights reserved.

Multifunctional Iron–Porphyrin Additive for Hole‐Transporting Layer Toward Efficient and Stable Perovskite Solar Cells

Spiro‐OMeTAD, as a crucial component of hole‐transporting layer (HTL), exhibits limited mobility and conductivity, and the lithium bis‐trifluoromethanesulfonimide dopant is sensitive to water vapor, which imposes restrictions on the photovoltaic properties of perovskite solar cells (PSCs). Herein, the iron–porphyrin (FePP) is introduced into Spiro‐OMeTAD solution as additive, which facilitates the oxidation process of Spiro‐OMeTAD, leading to the enhancement of hole mobility and hole extraction and transport. Besides, the surface Pb2+ defects of perovskite film are cured by the presence of carboxylic acids (COOH) in FePP. As a result, the photovoltaic properties of PSCs with FePP additive have been improved with a power conversion efficiency (PCE) of 21.58%. Moreover, FePP can further anchor Li+ ions in HTL to prevent it from being invaded by water vapor. Dramatically, the degradation of unencapsulated devices with FePP is suppressed significantly, which retains 82.0% of its original PCE under 10–20% relative humidity (RH) after 7100 h and maintains about 79.6% of its original PCE under 50–60% RH after 1000 h. Thus, this study shows that the design and development of multifunctional HTL additives holds great potential for achieving highly efficient and durable PSCs.

Erratum for the Research Article "Rational design of Lewis base molecules for stable and efficient inverted perovskite solar cells" by C. Li et al.

Erratum for the Research Article "Rational design of Lewis base molecules for stable and efficient inverted perovskite solar cells" by C. Li et al.

Ruddlesden-Popper Perovskite Nanocrystals as Interface Modification Layer for Efficient Perovskite Solar Cells.

Perovskite nanocrystals are advantageous for interfacial passivation of perovskite solar cells (PSCs), but the insulating long alkyl chain surface ligands impede the charge transfer, while the conventional ligand exchange would possibly introduce surface defects to the nanocrystals. In this work, we reported novel in situ modification of CsPbBr3 nanocrystals using a short chain conjugated molecule 2-methoxyphenylethylammonium iodide (2-MeO-PEAI) for interfacial passivation of PSCs. Transmission electron microscopy studies with atomic resolution unveil the transformation from cubic CsPbBr3 to Ruddlesden-Popper phase (RPP) nanocrystals due to halogen exchange. Synergic passivation by the RPP nanocrystals and 2-MeO-PEA+ has led to suppressed interface defects and enhanced charge carrier transport. Consequently, PSCs with in situ modified RPP nanocrystals achieved a champion power conversion efficiency of 24.39%, along with an improvement in stability. This work brings insights into the microstructural evolution of perovskite nanocrystals, providing a novel and feasible approach for interfacial passivation of PSCs.

Doping with KBr to Achieve High-Performance CsPbBr3 Semitransparent Perovskite Solar Cells.

Wide-bandgap semitransparent perovskite photovoltaics are emerging as one of the ideal candidates for building-integrated photovoltaics (BIPV). However, surface defects in inorganic CsPbBr3 perovskite prepared by vapor deposition severely limit the optoelectronic performance of perovskite solar cells. To address this issue, a strategy of doping a trace amount of KBr into perovskite by vapor deposition is adopted, effectively improving the quality of the film, reducing surface defect concentration, and enhancing the transportation and extraction of charge carriers. Simultaneously, fully physical vapor deposition technology is employed to fabricate perovskite solar cells with an average visible light transmittance of 44%. These devices exhibited an ultrahigh open-circuit voltage of 1.55 V and a superior power conversion efficiency (PCE) of 7.28%, demonstrating excellent moisture and heat resistance. Moreover, the corresponding 5 cm × 5 cm modules achieve a PCE of 5.35% with great thermal insulation capability. This work provides an approach for fabricating highly efficient all-inorganic perovskite solar cells with high average visible light transmittance, demonstrating new insights into their application in building-integrated photovoltaics.