Stable Perovskite Solar Cells Research Articles

Double Perovskite Interlayer Stabilized Highly Efficient Perovskite Solar Cells.

Metal halide perovskite solar cell (PSC) technology has an impressive power conversion efficiency (PCE) exceeding 26.1% and demonstrates cost-effective manufacturing. However, the stability of these PSCs poses a significant challenge, hindering their widespread manufacturing and commercialization. To tackle the degradation issue inherent in PSCs, surface passivation techniques, particularly employing a thin layer of two-dimensional (2D) perovskites, create a 2D/3D heterostructure. Beyond this, the exploration of metal halide double perovskites adds a new dimension to the chemical and band gap phase space of materials for optoelectronic applications. In this study, we leverage a wide band gap double perovskite interlayer to enhance the stability of 3D metal halide perovskite. Specifically, the double perovskite nanoparticle Cs2AgBiBr6, with its substantial band gap of 2.2 eV and exceptional air stability, is utilized. Through optimization, a Cs2AgBiBr6-treated PSC achieves an open-circuit voltage of 1.12 V and an impressive PCE of 19.52%. Additionally, the Cs2AgBiBr6 passivation layer proves to be effective in bolstering the stability of PSCs. This work demonstrates an additional strategy and design motif to simultaneously increase the PCE of PSCs along with achieving improved stability.

F for Fantastic: Fostering Stability and Efficiency in Perovskite Solar Cells via Comb-Like Perfluoroalkyl-g-Polyethylenimine Additive.

Additive engineering has emerged as a promising strategy to address the inherent instability challenges of perovskite solar cells (PSCs) in the pursuit of commercial viability. However, achieving multifunctionality using a singular additive remains a considerable challenge. In this study, a novel comb-like multifunctional perfluoroalkyl-g-polyethylenimmonium iodide (FPEI·HI) as additives to the PbI2 precursor solution to facilitate the formation of high-quality and water-resistant perovskite films is presented. FPEI·HI establishes robust interactions with both formamidinium iodide (FAI) and PbI2, mediated by hydrogen bonding and Lewis acid-base interactions. These interactions play a pivotal role in simultaneously passivating negative and positive charged defects within the perovskite structure. Furthermore, the inclusion of perfluoroalkyl chains serves as resilience against moisture intrusion. As a consequence of these effects, a notably high device efficiency of 24.29% is achieved, demonstrating comprehensive improvement in various photovoltaic parameters compared to the control device (22.51%). Notably, unencapsulated devices exhibit remarkable stability in high-humidity environments, retaining 90% of their initial efficiency even after 2500h of storage. This work underscores the efficacy of FPEI·HI as a critical enabler for enhancing the stability and efficiency of perovskite solar cells, marking a significant stride toward their commercialization.

Inorganic-Derived 0D Perovskite Induced Surface Lattice Arrangement for Efficient and Stable All-Inorganic Perovskite Solar Cells.

The inverted inorganic CsPbI3 perovskite solar cells (PSCs) are prospective candidates for next-generation photovoltaics owing to inherent robust thermal/photo-stability and compatibility for tandems. However, the performance and stability of the inverted CsPbI3 PSCs fall behind the n-i-p counterparts due to poor energetic alignment and abundant interfacial defect states. Here, an inorganic 0D Cs4PbBr6 with a good lattice strain arrangement is implemented as the surface anchoring capping layer on CsPbI3. The Cs4PbBr6 perovskite induces enhanced electron-selective junction and thus facilitates efficient charge extraction and effectively inhibits non-radiative recombination. Consequently, the CsPbI3 PSCs with Cs4PbBr6 demonstrate the highest power conversion efficiency (PCE) of CsPbI3-based inverted PSCs, reaching 21.03% PCE from a unit cell and 17.39% PCE from a module with a 64 cm2 aperture area. Furthermore, the resulting devices retain 92.48% after 1000h under simultaneous 1-sun and damp heat (85°C / 85% relative humidity) environment.

Amorphous (lysine)2PbI2 layer enhanced perovskite photovoltaics

Passivation materials play a crucial role in a wide range of high-efficiency, high-stability photovoltaic applications based on crystalline silicon and state-of-the-art perovskite materials. Currently, for perovskite photovoltaic, the mainstream passivation strategies routinely rely on crystalline materials. Herein, we have invented a new amorphous (lysine)2PbI2 layer-enhanced halide perovskite. By utilizing a solid phase reaction between PbI2 and lysine molecule, an amorphous (lysine)2PbI2 layer is formed at surface/grain boundaries in the perovskite films. The amorphous (lysine)2PbI2 with fewer dangling bonds can effectively neutralize surface/interface defects, achieving an impressive efficiency of 26.27% (certified 25.94%). Moreover, this amorphous layer not only reduces crystal lattice stress but also functions as a barrier against the decomposition of organic components, leading to suppressed de-structuring of perovskite and highly stable perovskite solar cells.

Molecular Design of Hole Transport Materials to Immobilize Ion Motion for Photostable Perovskite Solar Cells.

Poor operational stability is a crucial factor limiting the further application of perovskite solar cells (PSCs). Organic semiconductor layers can be a powerful means for reinforcing interfaces and inhibiting ion migration. Herein, two hole-transporting molecules, pDPA-SFX and mDPA-SFX, are synthesized with tuned substituent connection sites. The meta-substituted mDPA-SFX results in a larger dipole moment, more ordered packing, and better charge mobility than pDPA-SFX, accompanying with strong interface bonding on perovskite surfaces and suppressed ion motion as well. Importantly, mDPA-SFX-based PSCs exhibit an efficiency that has significantly increased from 22.5 % to 24.8 % and a module-based efficiency of 19.26 % with an active area of 12.95 cm2. The corresponding cell retain 94.8 % of its initial efficiency at maximum power point tracking (MPPT) after 1,000 h (T95=1,000 h). The MPPT T80 lifetime is as long as 2,238 h. This work illustrates that a small degree of structural variation in organic compounds leaves considerable room for developing new HTMs for light stable PSCs.

Screen-Assisted Self-Spreading of TiO2 Precursor Solution on FTO Substrates for High-Quality Electron Transport Layers in Perovskite Solar Cells.

The electron transport layer (ETL) plays a critical role in efficient and stable perovskite solar cells (PSCs). The current effective method for the large-scale preparation of metal oxide ETLs is mainly based on expensive sputtering processes. Here, a screen-assisted self-spreading method is proposed as a novel approach to prepare uniformly thin and conformal TiO2 films on a rough fluorine-doped tin oxide (FTO) substrate as an ETL in planar PSCs. The TiO2 ETL deposited by this method exhibited good coverage and homogeneity on the rough FTO substrate, thereby minimizing interfacial recombination. The photovoltaic performance of the PSCs fabricated by this method is superior to that of the cells fabricated by spin coating, especially in terms of the fill factor. The performance enhancement can be attributed to the complete coverage of the FTO substrate by the conformal TiO2 film, confirming the effectiveness and reliability of the proposed method for the preparation of the TiO2 ETL. The advantages of this method lie in its scalability to prepare oxide films with a large area, eliminating the requirement of complex equipment, such as spinners, sputters, or physical vapor deposition equipment.

Numerical simulation of all inorganic CsPbIBr2 perovskite solar cells with diverse charge transport layers using DFT and SCAPS-1D frameworks

All inorganic CsPbX3 perovskites (X = Br and I) are excellent candidates for stable and efficient perovskite solar cells (PSCs). Among them, CsPbIBr2 demonstrated the most balanced characteristics in terms of band gap and stability. Nevertheless, the power conversion efficiency (PCE) of CsPbIBr2-based solar cells is still far from that of Hybrid PSCs, and more research is required in this aspect. Herein, DFT and SCAPS-1D frameworks are employed to explore the optimized device configurations of CsPbIBr2 PSCs. DFT is used to explore the structural and optoelectronic characteristics of CsPbIBr2, while SCAPS-1D is employed to examine various device structures of CsPbIBr2-based PSCs. The band structure demonstrated the direct band gap nature of CsPbIBr2 with a band gap of 2.12 eV. Moreover, we have used TiO2, SnO2, ZnO, WS2, IGZO, CeO2, In2S3, and CdS as ETLs, and Cu2O, CuI, MoO3, NiO, CuSCN, CuSbS2, CBTS, CFTS, and CuO as HTLs for identifying the best ETL/CsPbIBr2/HTL configurations. Among 72 device combinations, eight sets of PSCs are identified as the most efficient configurations. In addition, the influence of various parameters like the thickness of various layers, doping concentration, perovskite defect density, ETLs and interfaces, series resistances, shunt resistances, and temperature on device performance have been comprehensively studied. The results demonstrate Cu2O as the best HTL for CsPbIBr2 with each ETL, and PSC with device structure ITO/WS2/CsPbIBr2/Cu2O/C exhibited the highest PCE of 16.53%. This comprehensive investigation will provide new path for the development of highly efficient all-inorganic CsPbIBr2 solar cells.

Uniform Molecular Adsorption Energy‐Driven Homogeneous Crystallization and Dual‐Interface Modification for High Efficiency and Thermal Stability in Inverted Perovskite Solar Cells

AbstractInterfacial defects between perovskite and adjacent charge transport layers present a significant obstacle, hindering the enhancement of power conversion efficiency (PCE) and stability in perovskite solar cells (PSCs). To address this challenge, a dual‐interface modification is proposed to aim at improving the performance of mixed‐halide PSCs. Specifically, the hole‐collecting side is modified with 5‐Aminopyridine‐2‐carboxylic Acid (APC), while the electron‐collecting side is modified with 2‐thiopheneethylammonium chloride (TEACl). The multifunctional APC enhances charge transfer by tailoring the interface between the perovskite and poly(triarylamine) (PTAA) through multiple bonding interactions, thereby suppressing interfacial nonradiative recombination. Density functional theory studies reveal that APC on the perovskite surface induces uniform adsorption energy, promoting homogenous crystallization without residual stress. Additionally, APC interlayer eliminates the localized edge states induced by the iodine vacancies near the conduction band edge. Further improvement in the device performance is achieved by passivating the top perovskite surface with TEACl, leading to well‐matched energy bands and reduced vacancy trap states. As a result, champion cell achieves a PCE of 24.87% with an open‐circuit voltage of 1.188 V. Furthermore, The dual‐interface modification improves thermal stability due to enhanced ion‐migration activation energy.

Enhancing efficiency and stability of perovskite solar cells with Bi2Te3 interlayer: insights from SCAPS simulation

Perovskite solar cells (PSCs) have gained much interest due to their high power conversion efficiencies (PCE). Affordable, accessible, and efficient solar energy is crucial for a sustainable and clean future. In this article, we optimized PSC efficiency and performance with an interlayer (IL) of Bi2Te3 (BT). Cell performance and efficiency were improved by incorporating BT IL with varied thicknesses. BT IL promotes electron transport while protecting the underlying structure from chemical instability, improving device performance. This simple and low-cost technology for producing efficient and stable all-inorganic PSC holds considerable potential as a next-generation renewable energy source. The main focus is optimizing all-inorganic PSC using Solar Cell Simulator Capacitance software (SCAPS). We systematically explore the influence of BT thickness and defect densities on the device performance. The impact of charge carrier transport and overall photovoltaic performance is studied. Our findings reveal that introducing the BT IL leads to improved charge extraction, reduced recombination losses, and enhanced stability in the PSC. The optimized device configuration significantly enhances PCE compared to reference devices without BT IL. This study provides valuable insights into the potential use of BT ILs as a strategy to boost the efficiency and stability of PSCs.

Efficient and stable perovskite solar cells via oxalic acid doped SnO2 nanocrystals with surface-defect passivation

The electron extraction and transfer play a crucial role in high performance of perovskite solar cells (PSCs). Tin dioxide (SnO2), with the high electrical conductivity and low photocatalytic activity, has been reported to be one of the most advantageous electron-transporting layers (ETL) in PSCs. However, a large number of non-radiative recombination defects have been reported in SnO2, which are attributed to the low tunability and lower dispersibility. Here, we propose a ligand-assisted tuning strategy based on the oxalic acid (OA) modification to control the SnO2 film and interfacial structure. This strategy can effectively inhibit the particle aggregation of SnO2 film. In addition, the bonding interaction between CO in the ligand and Sn in SnO2 and Pb atoms in the perovskite reduces the interfacial contact impedance and enhances the electron extraction. As a result, an impressive PCE of 22.68 %, a fill factor exceeding 0.82 and a Voc of 1.15 V were successfully obtained. In addition, the unencapsulated PSCs can maintain an initial efficiency of 93 % upon exposure to ambient air for 500 h.

Ultrafast hole transfer mediated by a conjugated self-assembled molecule enables efficient and stable wide-bandgap perovskite solar cells

Charge accumulations and electron recombination at the interfaces between perovskites and charge transporting materials are two critical factors significantly hindering the power conversion efficiency (PCE) and device stability of wide-bandgap perovskite solar cells (WBG PSCs). Herein, we tailor-made a self-assembled molecule (SAM), termed XS13, featuring an enlarged π-donor and a π-linker, to regulate the interface carrier dynamics in ∼1.8 eV WBG PSCs. Ultrafast spectroscopy clearly demonstrated that the XS13 facilitated the rapid extraction and transfer of photo-generated holes compared to the reference SAM-2PACz. Consequently, WBG PSCs based on XS13 achieved an outstanding PCE of up to 19.20 %, surpassing that of control devices (16.41 %). Furthermore, XS13-based WBG PSCs exhibited a remarkable suppression of light/electricity-induced halide ions migration, leading to significantly improved device stability. Our findings offer a new strategy for the rational design of hole transporting molecules with controlled properties to enhance device performance of PSCs.

Composites electron transport layer of PVA-regulated SnO2 for high-efficiency stable perovskite solar cells

As a new and efficient solar cell, perovskite solar cell has attracted wide attention due to its excellent performance. The electron transport layer in perovskite solar cells has a significant impact on device performance. SnO2 films that can be prepared by solution method have become the first choice for electron transport layer due to their simple process and excellent performance. However, the defects in SnO2 thin films and non-radiative recombination sites at the SnO2/Perovskite interface will lead to potential losses in the performance of photovoltaic devices. Therefore, in order to improve the interface loss and interface characteristics and prepare more efficient perovskite solar cells. In this work, a functional polymer, polyvinyl alcohol (PVA), is introduced to regulate the arrangement of SnO2 nanocrystals. The SnO2-PVA composite electron transport layer not only improves carrier transport, but also further affects the growth of perovskite films. PVA inhibits the agglomeration of tin dioxide particles by adding it to the aqueous solution of tin dioxide. Meanwhile, the oxygen vacancy defects in the SnO2 layer have also improved. Correspondingly, SnO2-PVA-based PSCs can be obtained a maximum efficiency of 23.73 %. Attributed to the strengthened interface binding and the improved perovskite crystallization process, the devices obtain good long-term stability, retaining 90 % of their initial performance after 1000 h operation at their maximum power point under 1 sun illumination.

Perovskite Quantum Dots for Solar Cells and Beyond

Halide perovskite solar cells have witnessed great successes recently while their instability is a big hurdle for practical application. Herein we discuss our recent progress in addressing the stability of perovskite solar cells, including introduction of capping layers to improve the stability against moisture and heat, and perovskite size engineering to suppress phase segregation. In particular, quantum dots (QDs) have the advantages of quantum confinement effect, defect-tolerant nature, and processability for flexible devices. We discuss a new surface ligand engineering strategy in designing new hybrid perovskite QDs with controllable compositions and sizes The QDs have been used as building blocks in quantum dot solar cells delivering a certified record efficiency of 16.6% with excellent long-term operation stability. By using QDs as light absorbing materials, the QD based photocatalysts also exhibited good stable performance in photocatalytic hydrogen production. The combination of perovskite QDs with Metal-Organic Framework (MOF) materials to form new composites led to ultrastable photoluminescent property for > 10,000 hours. The integration of perovskite solar cells and rechargeable batteries have led to a single module type rechargeable solar batteries with an overall storable solar energy conversion efficiency of >12%.

Enhancing Charge Transport and Stability in Perovskite Solar Cells via Integration with Porous Copper-Based Metal-Organic Frameworks

Enhancing Charge Transport and Stability in Perovskite Solar Cells via Integration with Porous Copper-Based Metal-Organic Frameworks

Unraveling Differences in the Effects of Ammonium/Amine-Based Additives on the Performance and Stability of Inverted Perovskite Solar Cells.

Additive engineering, with its excellent ability to passivate bulk or surface perovskite defects, has become a common strategy to improve the performance and stability of perovskite solar cells (PVSCs). Among the various additives reported so far, ammonium salts are considered an important branch. It is worth noting that although both ammonium-based additives (R-NH3 +) and amine-based additives (R-NH2) are derivatives of ammonia (NH3), the functions of the two can be easily confused due to their structural similarities. Moreover, there is no comprehensive comparative analysis of them in the literature. Here, the differences between phenethylammonium iodide (PEA+) and phenethylamine (PEA) additives are revealed experimentally and theoretically. The results clearly show that PEA outperforms PEA+ in terms of device performance and stability based on the following three factors: i) PEA's defect passivation capability is superior to that of PEA+; ii) PEA has better hydrophobicity to hinder water ingress; and iii) PEA completely improves the stability of PVSCs by enhancing thermal stability and inhibiting iodide migration in perovskite more effectively than PEA+. As a result, the power conversion efficiency (PCE) of the inverted methylammonium triiodide (MAPbI3) device using PEA increases by ≈15% to over 21%. More importantly, this device exhibits greater ability to prevent water invasion, thermal-induce degradation, and inhibit iodide ion migration, resulting in better long-term stability.

(Invited) Ion Migration Influencing Perovskite Solar Cell Performance and Stability

The thermodynamic and redox properties of halide perovskites provide a strong driving force for hole trapping and oxidation of iodide species. When in contact with a non-polar solvent, the migration of iodine species is further extended to expulsion of iodine from the perovskite film. Thus, the mobility of halides and their susceptibility to hole-induced oxidation play a crucial role in determining the long-term stability of metal halide perovskite solar cells. When Ruddlesden-Popper 2D mixed-halide perovskite films with spacer cations such as butylammonium are introduced into three-dimensional (3D) perovskite films, they can stabilize them against moisture-induced degradation at room temperature. While such passivation of 3D perovskites using 2D perovskites has been reported widely, the instability of the 2D/3D interface during long term solar cell operation can be problematic, especially at higher temperatures. The cation migration under light and heat can significantly alter the 2D/3D interface, thus affecting the solar cell performance. We have now probed the cation migration between 2D and 3D perovskites by physically pairing X PbI (X=butylammonium BA, oleylammonium OA, or phenethylammonium PEA) 2D film and (CH3)PbI3 3D film at different temperatures by recording changes in the absorption and emission spectra. Thus, suppression of halide ion migration as well as cation migration remains a key factor in achieving long term stability and improving efficiency of perovskite solar cells and light emitting devices.

Nitrogen-rich carbon dots as the antisolvent additive for perovskite-based photovoltaic devices

Solution-processed perovskite solar cells (PSCs) have demonstrated a tremendous growth in power conversion efficiency (PCE). A high-quality, defect-free perovskite-based active layer is a key point to enhance PSC performance. Introduction of additives and interlayers have proved to be an effective tool to passivate surface defects, control crystal growth, and improve PSC stability. Antisolvent engineering has emerged recently as a new approach, which aims to adjust perovskite layer properties and enhance the PCE and stability of PSC devices. Here, we demonstrate that carbon dots (CDs) may serve as a prospective additive for antisolvent engineering. Nitrogen-rich amphiphilic CDs were synthesized from amines by a solvothermal method and used as an additive to chlorobenzene for a perovskite layer fabrication. The interaction between perovskite and functional groups in CDs promotes improved crystallization of an active perovskite layer and defects passivation, bringing higher PSCs efficiency, stability, and suppressed hysteresis. Under optimized CD concentration, the maximum PCE increased by 34% due to the improved short-circuit current and fill factor, and the device maintains 87% of its initial efficiency after 6 d of storage under ambient conditions.

Understanding different oxidation methods for the hole transport layer Spiro-OMeTAD to improve perovskite solar cell performance

The preparation of a high-performance hole transport layer is a pivotal factor in achieving efficiency and stable perovskite solar cells. 2,2’,7,7’-Tetrakis[N, N-di(4-methoxyphenyl)amino]−9,9’-spirobifluorene (Spiro-OMeTAD) currently stands as the most widely employed hole transport material in high-performance perovskite solar cells. The current methodologies for its preparation primarily revolve around three techniques: O2 oxidation, cobalt salt doping, and CO2 bubbled doping. In this study, we systematically investigated and analyzed Spiro-OMeTAD prepared through these three methods, from solution and film to device. The CO2-bubbled method and Co-doped method allow for faster and more complete oxidation of Spiro-OMeTAD while maintaining conductivity and energy level matching. Therefore, the film of both methods shows better carrier extract capabilities and defect states than that of O2-oxidized. In particular, the film of the CO2-bubbled method had better hydrophobicity and thermal stability, showing the least degradation at 85 °C annealing, which can be attributed to the removal of hydrophilic Li+. This study could inspire further optimization of Spiro-OMeTAD film fabrication processes in perovskite solar cells.

Enhancing photovoltaic efficiency in perovskite solar cells through synergistic blending of polyvinyl alcohol and F-127 polymer in a sandwich architecture

In the field of photovoltaics, perovskite solar cells (PSCs) have become increasingly popular because of their cost-effective processing and competitive efficiency when compared to silicon solar cells. This work presents a novel design of a PSC based on methyl ammonium lead iodide (CH3NH3PbI3) and investigates the possibilities of organic-inorganic metal halides in the field of PSCs. The device has a sandwich architecture, where the hole transport material (HTM) operates at room temperature using a blend of polyvinyl alcohol (PVA) and F-127 polymer. Under typical solar conditions, the built-in PSC, which has the architecture FTO/TiO2/Perovskite/PVA & F-127/Pt, exhibits a remarkable efficiency of 1.29 %. Interestingly, PSC stability at room temperature is still a major problem, yet our design demonstrates a remarkable 2-h stability in ambient circumstances. This accomplishment is ground breaking because it introduces a high-efficiency PSC in a sandwich construction operating in ambient settings for the first time. The fact that this novel technique is solution-based and does not require vacuum deposition lends even more credence to its viability and scalability.

Suppressing the phase separation in FAMA mixed perovskite solar cells via the preloading of A site cations within the lattice

The incorporation of MA as a dopant is highly advantageous for stabilizing the lattice structure of α-phase FAPbI3. However, achieving a homogeneous phase mixing is only feasible at elevated MA doping levels, which significantly compromises both the efficiency and stability of FA-dominated perovskite solar cells (PSCs). In this study, it is found that in the nucleation stage of FAMA mixed perovskite, MA+ exhibit a significant kinetic advantage over FA+ in their reaction with PbI3−. The rapid crystallization of MAPbI3 not only induces FA-MA separation but also hinders the crystallization of perovskite due to strains induced by the bulky FA+ cations. To address this issue, we introduced FA0.8MA0.2PbI3 single crystals as the material source to prepare the precursor solutions, which achieved a delicate balance between lattice stability and bandgap (Eg = 1.54 eV). The preloaded A-site cations within the PbI3− cages make the bare FA-dominated perovskite films by blade coating maintain the phase stability in wild ambient for over one year. The final PSCs (0.09 cm2) achieved a highest power conversion efficiency (PCE) of 23.66 %, among the highest efficiency records for blade coated PSCs. The unpackaged PSCs show efficiency loss of < 10 % as being aged in air with a relative humidity of 10 % for over 1000 h.