Lead Iodide Perovskite Solar Cells Research Articles

Semiconductor heterojunctions coated with reduced graphite oxide as electron transfer materials for high-performance perovskite solar cells

Exploring and insight into the relationship between the microstructure, light absorption performance, and carrier transport of perovskite light absorption layer materials and carrier transport layer materials is crucial for obtaining efficient and stable perovskite solar cells. We adopted a simple strategy to prepare a composite material known as reduced graphene oxide wrapped mesoporous hierarchical TiO2–CdS semiconductor heterojunctions (TiO2–CdS-RGO) as the electron transport layer in formamidine lead iodide perovskite solar cells. Compared with single TiO2 and binary composite, this composite material exhibits enhanced photoluminescence quenching, reduced photo generated carrier recombination rate, and improved electron transfer capability. Photovoltaic devices based on TiO2–CdS-RGO composite material showed a 14.5 % increase in short-circuit current density (JSC) and a 36.3 % increase in photoelectric conversion efficiency (PCE) compared to those with only TiO2. The improved optoelectronic properties observed with the TiO2–CdS-RGO as electron transfer layers can be attributed to several factors. On the one hand, mesoporous TiO2 with a high specific surface area is beneficial for perovskite infiltration and enhances electron transfer rate. On the other hand, the well-matching energy level structure among the three components aids in electrons extraction and reduces the recombination rate of photo generated charge carriers; In addition, RGO nanosheets with high conductivity serve as an efficient electron transfer network, providing a rapid charge transfer pathways, which is crucial for enhancing the photoelectric conversion performance of perovskite solar cells.

Enhancing Internal and External Stability of Perovskite Solar Cells Through Polystyrene Modification of the Perovskite and Rapid Open‐Air Deposition of ZnO/AlOx Nanolaminate Encapsulation

In this study, the internal and external stabilities of a p–i–n methylammonium lead iodide perovskite solar cell (PSC) are improved. Polystyrene (PS) is introduced into the perovskite layer to form a cross‐linked polymer–perovskite network, which enhances the nucleation and growth of the perovskite grains. Moreover, for the first time, 60 nm thick ZnO/AlOx nanolaminate (NL) thin‐film encapsulation (TFE) is deposited directly on the PSC using an atmospheric‐pressure (AP) spatial atomic layer deposition system operated in AP spatial chemical vapor deposition (AP–SCVD) mode. The rapid nature of AP–SCVD enables encapsulation of the PSCs in open air at 130 °C without damaging the perovskite. The PS additive improves the performance and internal stability of the PSCs by reducing ion migration. Both the PS additive and the ZnO/AlOx NL TFEs improve the external stability under standard test conditions (dark, 65 °C, 85% relative humidity [RH]) by preventing water ingress. The number and thickness of the ZnO/AlOx NL layers are optimized, resulting in a water–vapor transmission rate as low as 5.1 × 10−5 g m−2 day−1 at 65 °C and 85% RH. A 14‐fold increase in PSC lifetime is demonstrated; notably, this is achieved using PS, a commodity‐scale polymer, and AP–SCVD, a scalable, open‐air encapsulation method.

Stable FAPbI3 Perovskite Solar Cells via Alkylammonium Chloride-Mediated Crystallization Control.

α-Phase formamidinium lead iodide (FAPbI3) perovskite solar cells (PSCs) have garnered significant attention, owing to their remarkable efficiency. Methylammonium chloride (MACl), a common additive, is used to control the crystallization of FAPbI3, thereby facilitating the formation of the photoactive α-phase. However, MACl's high volatility raises concerns regarding its stability and potential impact on the stability of the device. In this study, we partially substituted MACl with n-propylammonium chloride (PACl), which has a long alkyl chain, to promote the oriented crystallization of FAPbI3, ultimately forming an δ-phase-free perovskite. The FAPbI3 film containing PACl demonstrates an enhanced photoluminescence intensity and lifetime. Additionally, PACl's presence at grain boundaries acts as a protective layer for the PSCs. Consequently, we achieved a power conversion efficiency (PCE) of 22.4% and exceptional stability. It maintains over 95% of initial PCE for 100 days in an N2 glovebox, over 85% after 100 h of maximum power point tracking, and over 80% after 60 °C thermal aging.

Gel‐Derived Amorphous Precursor Enables Homogeneous Pure‐Phase α‐FAPbI3 Films for Efficient and Stable Perovskite Solar Cells

AbstractPure‐phase α‐formamidinium lead iodide (α‐FAPbI3) perovskite solar cells (PSCs) possess potential high efficiency because of suitable bandgap. However, achieving high‐quality α‐FAPbI3 films during the spin‐coating process is challenging without anti‐solvent extraction, due to the spontaneous formation of the more stable δ‐FAPbI3 phase and the complexity of multi‐component perovskite precursor solutions. Here a gel precursor with an amorphous structure to eliminate the need for anti‐solvent extraction in achieving the homogeneous and highly oriented pure‐phase α‐FAPbI3 is devised films. The incorporation of N,N′‐dimethylpropyleneurea, and alkylammonium chloride results in extended iodoplumbate clusters in the perovskite precursor solution. In situ, spectroscopic analysis reveals that the emergence of the stable amorphous gel precursor during the initial solidification stage ensures a uniform solute distribution. This effectively prevents preferentially oriented growth in the crystal phase precursor, leading to a significant enhancement in film homogeneity. As a result, power conversion efficiencies of 24.17% for the PSC, and 19.3% for the module are achieved, along with superior operational stability, retaining 96.1% of their initial efficiency after 850 h at the maximum power point tracking. These demonstrate the best performance for the reported pure‐phase α‐FAPbI3 PSCs without anti‐solvent extraction, showing great promise for scalable manufacture.

Synergistic Enhancement of Stability and Performance for Perovskite Solar Cells Using Fluorinated Benzoic Acids as Additives

The introduction of additives with specific functional groups is an important approach to extend the operational lifetime of perovskite solar cells (PSCs). Herein, the effect of the additives of benzoic acid (0F‐B), 4‐fluorobenzoic acid (1F‐B), and 2,3,4,5,6‐pentafluorobenzoic acid (5F‐B) on the performance and stability of MAPbI3‐based PSCs is systematically investigated. These additives can both chelate onto lead ions and form hydrogen bond with methyl ammonium ions. These combined interactions result in an increased activation energy for nucleation of perovskite crystals, thereby, increasing crystal size, reducing defect formation, improving electronic properties, as well as reducing ion migration. As a result, PSCs added with 5F‐B achieve the highest power conversion efficiency (PCE) of 20.50% with a narrow distribution compared to those PSC devices added with 1F‐B (19.25 %), 0F‐B (18.80 %), and pristine devices (18.53 %). Notably, 5F‐B‐added PSCs retain 80% of their initial PCE after ≈100‐day humidity test (at 25 °C and 50% relative humidity), 30‐day thermal stability test (at 85 °C in nitrogen environment), and 12‐day light illumination test (under continuous simulated solar radiation).

ZnO/SnO2 bilayer electron transport layer strategy to improve the performance of FAPbI3 solar cell

In recent years, organic–inorganic hybrid perovskite (PVK) devices have attracted widespread attention with their high absorption coefficient and low-cost fabrication process. Formamidinium lead iodide (FAPbI3) perovskite solar cells (PSCs) have been reported to obtain high power conversion efficiencies (PCEs) due to the narrow bandgap. Zinc oxide (ZnO) has better electrical conductivity and high transmittance than tin (IV) dioxide (SnO2). However, the deprotonation behavior of ZnO limits its use in formamidinium (FA) or methylammonium (MA) devices, so it is mostly used in all-inorganic PSCs. In this work, to avoid the deprotonation behavior of ZnO, we prepared FAPbI3 PSCs using ZnO/SnO2 as bilayer electron transporting layers (ETLs), which improved the conductivity of the ETLs and promoted electron extraction and transfer. In addition, the decrease in the oxygen vacancy (Ov) on the bilayer ETLs contributed to the suppression of the non-radiative recombination of the device, thus enabling the achievement of a higher fill factor. As a result, the modified ETLs increased the PCE of FAPbI3 PSCs from 20.24% to 21.42% and improved the stability of the devices. The PCE of unpackaged devices increased steadily to 21.91% when stored in an N2 atmosphere for 183 days.

Deciphering Reaction Products in Formamidine-Based Perovskites with Methylammonium Chloride Additive.

The fabrication of formamidinium lead iodide (FAPbI3) perovskite solar cells (PSCs) involves the addition of methylammonium chloride (MACl) to promote low-temperature α-phase formation and grain growth. However, as the added MACl deprotonates and volatilizes into methylamine (MA0) and HCl for removal, MA0 can chemically interact with formamidinium (FA+), forming methyl formamidinium (MFA+) as a byproduct. Despite its significance, the chemical interactions among FAPbI3 perovskites, MACl additives, and their byproducts remain poorly understood. Our findings reveal that the FA+ and MA0 reaction primarily yields a mixture of cis/trans-N-methyl formamidinium iodide (MFAI) isomers, with cis-MFAI prevailing as the dominant species. Moreover, MFAI subsequently reacts with PbI2 to yield fully formed cis-MFAPbI3 2H-phase perovskite. We elucidated the effects of MFAI on the crystal growth, phase stability, and band gap of formamidine-based perovskites through the growth of single crystals. This research offers valuable insights into the role of these byproducts in influencing the efficiency and long-term stability of future PSCs.

Caffeine additive based nanoarchitectonics of methylammonium lead iodide (MAPbI3) perovskite solar cell device: investigations on charge carrier properties using AC impedance spectroscopy

Caffeine additive based nanoarchitectonics of methylammonium lead iodide (MAPbI3) perovskite solar cell device: investigations on charge carrier properties using AC impedance spectroscopy

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.

Bar Coating Process of Two-Dimensional Lead Iodide Perovskite Solar Cells: Effects of Vertical Orientation, Anisotropic Photoconductivity, and Conversion Time

Bar Coating Process of Two-Dimensional Lead Iodide Perovskite Solar Cells: Effects of Vertical Orientation, Anisotropic Photoconductivity, and Conversion Time

Effects of Co-Addition of Guanidinium and Cesium to CH3NH3PbI3 Perovskite Solar Cells

The effects of guanidinium (C(NH2)3, GA) and cesium (Cs) co-additions on methylammonium lead iodide (CH3NH3PbI3, MAPbI3) perovskite solar cells were investigated. The first-principles calculations on the density of the states and band structures showed a reduction in the total energy by the GA addition. Although the calculation showed that the co-addition of the GA/Cs to the MAPbI3 perovskite could decrease the carrier mobilities, and the addition of GA/Cs improved the device performance. This result would be due to a facilitation of grain growth and a suppression of the defects from the GA/Cs addition. The changes to the conversion efficiencies of the device with the best performance were small, which indicates that the present co-addition of GA/Cs is effective for the stability of the devices.

Laser Derived Electron Transport Layers with Embedded p-n Heterointerfaces Enabling Planar Perovskite Solar Cells with Efficiency over 25.

Electron transport layers (ETLs) with pronounced electron conducting capability are essential for high performance planar perovskite photovoltaics, with the great challenge being that the most widely used metal oxide ETLs unfortunately have intrinsically low carrier mobility. Herein is demonstrated that by simply addressing the carrier loss at particle boundaries of TiO2 ETLs, through embedding in ETL p-n heterointerfaces, the electron mobility of the ETLs can be boosted by three orders of magnitude. Such embedding is encouragingly favorable for both inhibiting the formation of rutile phase TiO2 in ETL, and initiating the growth of high-quality perovskite films with less defect states. By virtue of these merits, creation of formamidinium lead iodide perovskite solar cells (PSCs) with a champion efficiency of 25.05% is achieved, setting a new benchmark for planar PSCs employing TiO2 ETLs. Unencapsulated PSCs deliver much-improved environmental stability, i.e., more than 80% of their initial efficiency after 9000 h of air storage under RH of 40%, and over 90% of their initial efficiency at maximum power point under continuous illumination for 500 h. Further work exploring other p-type nanocrystals for embedding warrants the proposed strategy as a universal alternative for addressing the low-carrier mobility of metal oxide based ETLs.

Simulation Analysis of Formamidinium Lead Iodide Perovskite Solar Cells as Function of Thickness and Defects of Absorber Layer, Hole and Electron Transport Layer Under SCAPS-1D

Simulation Analysis of Formamidinium Lead Iodide Perovskite Solar Cells as Function of Thickness and Defects of Absorber Layer, Hole and Electron Transport Layer Under SCAPS-1D

Fully Methylammonium-Free Stable Formamidinium Lead Iodide Perovskite Solar Cells Processed under Humid Air Conditions.

Fabricating perovskite solar cells (PSCs) in ambient air condition is beneficial for lowering the processing cost and boosting the commercialization. Formamidinium lead iodide (FAPbI3) is an attractive candidate for efficient PSCs; however, it easily suffers from degradation and phase transition in the presence of ambient moisture. Methylammonium (MA) cation is commonly incorporated to stabilize FAPbI3, whereas the residual MA tends to deteriorate the thermal and operational stability. Herein, we report a MA-free strategy to fabricate high-quality α-FAPbI3 films and inverted PSCs under open air conditions with a relative humidity (RH) of 60 ± 10%. The incorporation of phenylethylammonium iodide (PEAI) effectively inhibits the decomposition and phase transition of FAPbI3 during its crystallization in humid air. Accordingly, phase-pure α-FAPbI3 perovskite films with significantly reduced δ-FAPbI3 and PbI2 content are successfully obtained. In addition, introducing PEAI strongly enhances the crystallinity of FAPbI3 perovskite films, thereby yielding enlarged grain sizes and reduced grain boundaries. Defects at the grain boundaries and surface are further passivated by PEAI addition, so that the trap state density is significantly decreased. As a result, the non-radiative recombination is effectively suppressed and the charge carrier transport is promoted. The inverted device optimized with a suitable PEAI concentration exhibits an enhanced power conversion efficiency (PCE) of 17.83%, which significantly surpasses the control device (12.29% PCE). Moreover, the PEAI optimized FAPbI3 PSCs demonstrate strongly improved long-term stability, with nearly 97% PCE maintained after 27-day storage under ambient conditions. This work provides a feasible way to fabricate PSCs in ambient air for promoting their wide range of applications.

Modeling the path to >30% power conversion efficiency in perovskite solar cells with plasmonic nanoparticles.

Mixed organic-inorganic halide perovskite solar cells (PSCs) are a promising technology with increasing power conversion efficiency (PCE), low-cost material constituents, simple scalability, and a low-temperature solution fabrication process. Recent developments have seen energy conversion efficiencies increase from 3.8% to over 20%. However, to further improve PCE and reach the target efficiency of over 30%, light absorption through plasmonic nanostructures is a promising approach. In this work, we present a thorough quantitative analysis of the absorption spectrum of a methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell using a nanoparticle (NP) array. Our multiphysics simulations using finite element methods (FEM) show that an array of Au nanospheres can increase average absorption >45%, compared to only 27.08% for the baseline structure without any NPs. Furthermore, we investigate the combined effect of engineered enhanced absorption on electrical and optical solar cell performance parameters using the one-dimensional solar cell capacitance software (SCAPS 1-D), which shows a PCE of ∼30.4%, significantly higher than the PCE of ∼21% for cells without NPs. Our findings demonstrate the potential of plasmonic perovskite research for next-generation optoelectronic technologies.

Towards low-temperature processing of efficient γ-CsPbI3 perovskite solar cells.

Inorganic cesium lead iodide (CsPbI3) perovskite solar cells (PSCs) have attracted enormous attention due to their excellent thermal stability and optical bandgap (∼1.73 eV), well-suited for tandem device applications. However, achieving high-performance photovoltaic devices processed at low temperatures is still challenging. Here we reported a new method for the fabrication of high-efficiency and stable γ-CsPbI3 PSCs at lower temperatures than was previously possible by introducing the long-chain organic cation salt ethane-1,2-diammonium iodide (EDAI2) and regulating the content of lead acetate (Pb(OAc)2) in the perovskite precursor solution. We find that EDAI2 acts as an intermediate that can promote the formation of γ-CsPbI3, while excess Pb(OAc)2 can further stabilize the γ-phase of CsPbI3 perovskite. Consequently, improved crystallinity and morphology and reduced carrier recombination are observed in the CsPbI3 films fabricated by the new method. By optimizing the hole transport layer of CsPbI3 inverted architecture solar cells, we demonstrate efficiencies of up to 16.6%, surpassing previous reports examining γ-CsPbI3 in inverted PSCs. Notably, the encapsulated solar cells maintain 97% of their initial efficiency at room temperature and under dim light for 25 days, demonstrating the synergistic effect of EDAI2 and Pb(OAc)2 in stabilizing γ-CsPbI3 PSCs.

Application of porosities in the transparent electrode layer of a perovskite solar cell for performance enhancement.

Substitution of monocrystalline or polycrystalline silicon as active materials in photovoltaics with highly efficient perovskite materials is quite common. Although perovskite materials offer better flexibility, are cost-effective, and have higher conversion efficiency, they still require structural modifications for better performance. This study quantitatively investigates how mesoporous top surfaces improve the performance of methylammonium lead iodide (C H 3 N H 3 P b I 3) perovskite solar cells. In fact, both the diameter and the depth of the pores have been tuned to achieve better performance. The performance is further optimized by replacing mesoporous active material with planar active material coated with mesoporous indium tin oxide (ITO). We have demonstrated that the proposed structure achieves the maximum conversion efficiency (η) of 27.43% with an open-circuit voltage (V O C ) of 1.07V and a short circuit current density (J S C ) of 29.09m A/c m 2, with a fill factor (FF) of 88.10%.

Stability and degradation in triple cation and methyl ammonium lead iodide perovskite solar cells mediated via Au and Ag electrodes

Perovskite solar cells (PSCs), particularly based on the methyl ammonium lead iodide (MAPbI3) formulation, have been of intense interest for the past decade within the photovoltaics (PV) community, given the stupendous rise in power conversion efficiencies (PCEs) attributed to these perovskite formulations, where PCEs have exceeded 25%. However, their long-term stability under operational conditions and environmental storage are still prime challenges to be overcome towards their commercialization. Although studies on the intrinsic perovskite absorber stability have been conducted previously, there are no clear mechanisms for the interaction of electrode-induced absorber degradation pathways, which is the focus of this study. In this report, we have conducted a comprehensive analysis on the impact of the electrode collector layer, specifically Ag and Au, on the degradation mechanism associated with the MAPbI3 and a triple cation absorber, Cs0.05FA0.79MA0.16PbI2.45Br0.55. Notably, Au-based PSCs for both absorbers in an n-i-p architecture showed superior PCE over Ag-based PSCs, where the optimized PCE of MAPbI3 and triple cation-based PSCs was 15.39% and 18.21%, respectively. On the other hand, optimized PCE of MAPbI3 and triple cation-based PSCs with Ag electrodes was 3.02% and 16.44%, respectively. In addition, the Ag-based PSCs showed a rapid decrease in PCE over Au-based PSCs through operational stability measurements. We hypothesize the mechanism of degradation, arising from the Ag interaction with the absorber through the formation of AgI in the PSCs, leads to corrosion of the perovskite absorber, as opposed to the benign AuI when Au electrodes are used in the solar cell stack. Additionally, novel use of photoluminescence spectroscopy (PL) here, allowed us to access key features of the perovskite absorber in situ, while it was in contact with the various layers within the n-i-p solar cell stack. A quenching in the PL peak in the case of Ag-contacted MAPbI3 provided direct evidence of the Ag corrupting the optical properties of the absorber through the formation of AgI which our X-ray diffraction (XRD) results confirmed. This was supported by the fact that an emission peak was still present in the triple cation Ag-device. For the Au-contacted MAPbI3 the presence of a well-defined PL peak, though attenuated from the triple cation Au-device, suggested the AuI does not quell the emission spectrum for either the triple cation or the MAPbI3 absorber. The findings should aid in the understanding and design of new electrode materials with PSCs, which will help accelerate their introduction into the commercial sector in the future.

Configuration of Methylammonium Lead Iodide Perovskite Solar Cell and its Effect on the Device's Performance: A Review

AbstractIn its initial phase in 2009, the inorganic‐organic hybrid perovskite solar cells (PSCs) delivered a 3.8% power conversion efficiency (PCE), which is far below the present 25.7% PCE obtained in 2022. The significant improvement of the efficiency of PSCs in such a short period has stimulated significant interest in the photovoltaic community. However, the performance of current PSCs is behind the commercially available and widely used solar cells in terms of stability and scalability. Among various commonly studied perovskite materials, methylammonium lead iodide (MAPbI3) is the most widely studied. This review will focus on the common solar cell structures (mesoporous, inverted planar p‐i‐n, planar n‐i‐p) using MAPbI3 perovskite as an active layer and the effect of these solar cell structures on their performances. Furthermore, some commonly‐used strategies are outlined for improving the device performance, such as optimizing the deposition technique of the charge transporting and the active layers, modifying the properties of the carrier transporting layer and the perovskite layer by interface engineering and doping, optimizing the perovskite surface morphology, along with others. This article will also discuss the hole transport free and electron transport free MAPbI3 PSCs.

Triarylamine/Bithiophene Copolymer with Enhanced Quinoidal Character as Hole‐Transporting Material for Perovskite Solar Cells

[100]Polytriarylamine is a popular hole-transporting materials (HTMs) despite its suboptimal conductivity and significant recombination at the interface in a solar cell setup. Having noted insufficient conjugation among the triarylamine units along the polymer backbone, we inserted a bithiophene unit between two triarylamine units through iron-catalyzed C-H/C-H coupling of a triarylamine/thiophene monomer so that two units conjugate effectively via four quinoidal rings when the molecule functions as HTM. The obtained triarylamine/bithiophene copolymer (TABT) used as HTM showed a high-performance in methylammonium lead iodide perovskite (MAPbI3 ) solar cells. Mesityl substituted TABT forms a uniform film, shows high hole-carrier mobility, and has an ionization potential (IP=5.40 eV) matching that of MAPbI3 . We fabricated a solar cell device with a power conversion efficiency of 21.3 % and an open-circuit voltage of 1.15 V, which exceeds the performance of devices using reference standard such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA) and Spiro-OMeTAD.