Perovskite Solar Cells Research Articles

The Molecular Additive N-Acetyl-L-Phenylalanine Delays the Crystallization and Suppresses the Phase Impurity for Achieving Triple-Cation Perovskite Solar Cells with Efficiency Over 25.

The crystallization process plays an important role in the formation of high-quality perovskite film for achieving efficient perovskite solar cells (PSCs), especially in the formation of mixed-cation perovskite film, as there are normally more phase impurities than in pure CH(NH2)2PbI3 (FAPbI3) film. Herein, a molecular additive strategy, i.e., introducing non-planar molecule N-acetyl-L-phenylalanine (APO) into the lead iodide (PbI2) precursor solution, is proposed to modulate crystallization kinetics and inhibit the generation of phase impurities of metastable pretreated perovskite film. The delayed crystallization process promotes a sufficient reaction between organic salts solution and inorganic Pb-I framework, and perovskite phase decomposition is prevented by forming strong hydrogen bonds between ─NH and I, resulting in the formation of uniform film with large-size crystal grains and high-purity crystalline phase. Ultimately, the target PSC devices achieve an impressive power conversion efficiency (PCE) of 25.05%, which is among the highest values of triple-cation (FAMACs) PSCs. Meanwhile, PSC modules with 10.8 cm2 obtain a PCE of 20.35%. Furthermore, the unencapsulated PSCs retain 94% of the initial efficiency after 40 days of storage under ambient conditions with 20% RH and also yield superior operational stability under light soaking at maximum power point tracking (MPPT) in nitrogen (N2) atmosphere.

Suppressing Interface Defects in Perovskite Solar Cells via Introducing a Plant-Derived Ergothioneine Self-Assembled Monolayer

Perovskite solar cells are among the most promising renewable energy devices, and enhancing their stability is crucial for commercialization. This research presents the use of L-Ergothioneine (L-EGT) as a passivation material in perovskite solar cells, strategically placed between the electron transport layer and the perovskite absorber layer to mitigate defect states at the heterojunction interface. Surface analysis reveals that introducing L-EGT passivation material significantly improves the quality of the perovskite film. X-ray diffraction analysis indicates that L-EGT slows down perovskite film degradation and successfully suppresses secondary phase formation. X-ray photoelectron spectroscopic analysis shows that oxygen vacancies in the lattice decrease from 29.21% to 15.81%, while Ti4+ content increases from 70.75% to 79.15%, suggesting that L-EGT effectively passivates trap states at the interface between perovskite and TiO2 electron transport layer. The reduction of defects at the interface inhibits charge accumulation and lowers the device’s internal series resistance, leading to improved overall performance. The study finds that the introduction of L-EGT significantly improves the fill factor and efficiency, with the power conversion efficiency (PCE) rising from 16.88% to 17.84%. After 720 h of aging, the PCE retains approximately 91%. The results demonstrate the significant impact of the amino acid L-EGT passivation material in suppressing interfacial defects and greatly improving the long-term stability of perovskite devices.

A green solvent enables precursor phase engineering of stable formamidinium lead triiodide perovskite solar cells

Perovskite solar cells (PSCs) offer an efficient, inexpensive alternative to current photovoltaic technologies, with the potential for manufacture via high-throughput coating methods. However, challenges for commercial-scale solution-processing of metal-halide perovskites include the use of harmful solvents, the expense of maintaining controlled atmospheric conditions, and the inherent instabilities of PSCs under operation. Here, we address these challenges by introducing a high volatility, low toxicity, biorenewable solvent system to fabricate a range of 2D perovskites, which we use as highly effective precursor phases for subsequent transformation to α-formamidinium lead triiodide (α-FAPbI3), fully processed under ambient conditions. PSCs utilising our α-FAPbI3 reproducibly show remarkable stability under illumination and elevated temperature (ISOS-L-2) and “damp heat” (ISOS-D-3) stressing, surpassing other state-of-the-art perovskite compositions. We determine that this enhancement is a consequence of the 2D precursor phase crystallisation route, which simultaneously avoids retention of residual low-volatility solvents (such as DMF and DMSO) and reduces the rate of degradation of FA+ in the material. Our findings highlight both the critical role of the initial crystallisation process in determining the operational stability of perovskite materials, and that neat FA+-based perovskites can be competitively stable despite the inherent metastability of the α-phase.

Idealizing Air‐Processed Perovskite Film Competitive by Surface Lattice Etching‐Reconstruction for High‐Efficiency Solar Cells

Air‐processed perovskite solar cells are desirable for the large‐scale manufacturing application in the future, yet the presence of moisture and oxygen goes against perovskite crystallization and deteriorates phase stabilization, leading to the formation of substantial defective nano‐impurities, especially on the vulnerable surface. Here, we propose a strategy to simultaneously remove superficial defect layer and solidify the surface by soaking air‐fabricated perovskite film into low‐polar organic esters at elevated temperature to trigger an in‐situ dynamic surface lattice disassemble and reconstruction process. Molecular dynamics simulations and experimental results indicate that the inorganic CsPbI2Br perovskite is first dissolved and then the Br‐rich phase is recrystallized at solid‐liquid interface owing to the balance between weak solubility and high‐temperature induced annealing process, thus hardening the soft surface and releasing the lattice tensile stress, which benefits the minimization of interfacial recombination and improvement of the structural stability. As a result, we prepare a carbon‐based CsPbI2Br device in complete air without precise control on humidity, achieving a champion efficiency of 15.37% with excellent resistance to harsh attackers. This method offers a promising avenue for overcoming the limit of processing conditions on advancing perovskite‐based optoelectronic devices.

Amidination of ligands for chemical and field-effect passivation stabilizes perovskite solar cells.

Surface passivation has driven the rapid increase in the power conversion efficiency (PCE) of perovskite solar cells (PSCs). However, state-of-the-art surface passivation techniques rely on ammonium ligands that suffer deprotonation under light and thermal stress. We developed a library of amidinium ligands, of interest for their resonance effect-enhanced N-H bonds that may resist deprotonation, to increase the thermal stability of passivation layers on perovskite surfaces. This strategy resulted in a >10-fold reduction in the ligand deprotonation equilibrium constant and a twofold increase in the maintenance of photoluminescence quantum yield after aging at 85°C under illumination in air. Implementing this approach, we achieved a certified quasi-steady-state PCE of 26.3% for inverted PSCs; and we report retention of ≥90% PCE after 1100 hours of continuous 1-sun maximum power point operation at 85°C.

Idealizing Air-Processed Perovskite Film Competitive by Surface Lattice Etching-Reconstruction for High-Efficiency Solar Cells.

Air-processed perovskite solar cells are desirable for the large-scale manufacturing application in the future, yet the presence of moisture and oxygen goes against perovskite crystallization and deteriorates phase stabilization, leading to the formation of substantial defective nano-impurities, especially on the vulnerable surface. Here, we propose a strategy to simultaneously remove superficial defect layer and solidify the surface by soaking air-fabricated perovskite film into low-polar organic esters at elevated temperature to trigger an in-situ dynamic surface lattice disassemble and reconstruction process. Molecular dynamics simulations and experimental results indicate that the inorganic CsPbI2Br perovskite is first dissolved and then the Br-rich phase is recrystallized at solid-liquid interface owing to the balance between weak solubility and high-temperature induced annealing process, thus hardening the soft surface and releasing the lattice tensile stress, which benefits the minimization of interfacial recombination and improvement of the structural stability. As a result, we prepare a carbon-based CsPbI2Br device in complete air without precise control on humidity, achieving a champion efficiency of 15.37% with excellent resistance to harsh attackers. This method offers a promising avenue for overcoming the limit of processing conditions on advancing perovskite-based optoelectronic devices.

3T-VASP: fast ab-initio electrochemical reactor via multi-scale gradient energy minimization

Ab-initio methods such as density functional theory (DFT) is useful for fundamental atomistic-level study and is widely used across many scientific fields, including for the discovery of electrochemical reaction byproducts. However, many DFT steps may be needed to discover rare electrochemical reaction byproducts, which limits DFT’s scalability. In this work, we demonstrate that it is possible to generate many elementary electrochemical reaction byproducts in-silico using just a small number of ab-initio energy minimization steps if it is done in a multi-scale manner, such as via previously reported tiered tensor transform (3T) method. We first demonstrate the algorithm through a simple example of a complex floppy organic molecule passivator binding onto perovskite solar cell surface defect site. We then demonstrate more complex examples by generating hundreds of electrochemical reaction byproducts in lithium-ion battery liquid electrolyte (many are verified in previous experimental studies), with most trajectories completed within 50–100 DFT steps as opposed to more than 10,000 steps typically utilized in an ab-initio molecular dynamics trajectory. This approach requires no machine learning training data generation and can be directly applied on any new chemistries, making it suitable for ab-initio elementary chemical reaction byproduct investigation when temperature dependence is not required.

Dual-Passivation Strategy of Bulk and Surface Enables Highly Efficient and Stable Inverted Perovskite Solar Cells.

Inverted perovskite solar cells (PSCs) have captured significant interest due to their outstanding stability, cost-effective fabrication process, and good compatibility with flexible and tandem devices. The presence of bulk and surface defects is key factor in PSCs that cause non-radiative recombination and degradation. To improve the efficiency and stability of inverted PSCs, a bulk-to-surface dual-passivation strategy is employed by utilizing Oleylamine Iodide (OAmI) as additives and 4-Fluorobenzylamine Hydroiodide (4-F-PMAI) as surface passivating agents. Utilizing OAmI as bulk passivation can enhance the crystallinity of perovskite films and reduce lattice defects. Meanwhile, 4-F-PMAI further suppresses non-radiative recombination and reduces open-circuit voltage (VOC) loss through bidentate anchoring. Consequently, the dual-passivation strategy significantly enhances device performance, boosting the power conversion efficiency (PCE) of PSCs to 24.26%, with a VOC of 1.15V. Moreover, the unencapsulated PSCs show excellent long-term stability maintaining over 85% and 90% of the initial efficiency under 85°C thermal annealing in N2 for 1000 hours and after storage in ambient conditions (RH: 30 ± 5%) for 1000 hours.

Enhancing the Efficiency and Stability of Perovskite Solar Cells Via Hybrid Electron Transport Layer Strategy.

Tin oxide (SnO2) is extensively employed as the electron transport layer (ETL) for perovskite solar cells, but the presence of unsaturated Sn dangling bonds and oxygen vacancy defects at surface hinders effective carrier transport. Herein, we present an effective strategy for constructing a hybrid ETL by doping ZnF2 into the SnO2, effectively addressing the oxygen vacancy defects at both the bulk and interface of SnO2, thus markedly minimizing nonradiative recombination losses. Additionally, the process-induced strong bonding between F and Sn atoms facilitates the establishment of electron transfer pathways, leading to an increased electron cloud density within SnO2 and enhanced electron transfer capability, thus further suppressing charge accumulation at the interface. The hybrid ETL strategy can be adaptable to perovskites with various cations. The MAPbI3 and Cs0.1FA0.9PbI3 perovskite solar cells achieved remarkable PCEs of 21.31% and 24.91%, respectively. Moreover, the hybrid ETL design significantly enhances device stability. After 600 h of ambient storage, the unencapsulated optimized devices retained approximately 90% of their initial efficiency.

Unraveling Ion Migration Mechanisms under Operating Conditions in Perovskite Solar Cells by Variable-Load Transient Photoelectric Technique.

Ion migration in perovskite solar cells (PSCs) significantly impacts their photoelectric performance and physicochemical stability. Existing research has predominantly focused on inhibiting ion migration through chemical strategies or observing it under open-circuit or short-circuit conditions. This focus has led to a limited theoretical understanding and control of ion migration under practical conditions, constraining advances in long-term stability. In this study, we introduce a novel variable-load transient photoelectric technique (VL-TPT) to investigate ion migration dynamics in PSCs under practical operating conditions. Results show that ion accumulation correlates with photogenerated carrier concentration under open-circuit conditions. During operation, ion accumulation decreases with reduced load, because charge is transferred to the external circuit, leading to a reduction in carrier concentration within the device. An unusual increase in interface ions is observed at low loads due to interactions between charges accumulated in the potential well and ions. Introducing FA+ in MA0.75FA0.25PbI3 devices suppresses ion migration in the open-circuit state but accelerates interface ion buildup under operating conditions. These findings provide valuable insights for enhancing device stability and performance.

Energy Level Alignment Regulation and Carrier Management in Perovskite Solar Cells with Various Bandgaps Using Tailored Metal‐Organic Frameworks

Energy Level Alignment Regulation and Carrier Management in Perovskite Solar Cells with Various Bandgaps Using Tailored Metal‐Organic Frameworks

Recent Advances and Remaining Challenges in Perovskite Solar Cell Components for Innovative Photovoltaics

Recent Advances and Remaining Challenges in Perovskite Solar Cell Components for Innovative Photovoltaics

Melt Alloying of Two-Dimensional Hybrid Perovskites: Composition-Dependence of Thermal and Optical Properties.

Melt alloying, the process of melting a physical powder blend to create a homogeneous alloy, is widely used in materials processing. By carefully selecting the materials and their proportions, the physical properties of the resulting alloy can be precisely controlled. In this study, we investigate the possibility of utilizing melt alloying principles for meltable two-dimensional hybrid organic-inorganic perovskites (2D-HOIPs). We blend and melt mixtures of two selected 2D-HOIPs: the glass-forming (S-NEA)2PbBr4 (S-NEA = (S)-(-)-1-(1-naphthyl)ethylammonium) and the liquid-forming (1-MHA)2PbI4 (1-MHA = 1-methylhexylammonium). Upon melting and cooling, 1-MHA-poor blends (X1-MHA ≤ 50% mol, where X1-MHA corresponds to the relative molar concentration of (1-MHA)2PbI4 in the blend) form a hybrid glass, while 1-MHA-rich blends (X1-MHA ≥ 70% mol) crystallize. The melting temperature of all blends, as well as the glass transition temperature of the glass-forming blends, change according to blend composition. In all cases, melting produces a homogeneous structure, either glassy or crystalline, which remains such after the glassy samples are recrystallized upon a second heat treatment. This method enables band gap tuning of the blends, given that it varies with composition and crystallinity. Overall, this work demonstrates the applicability of classical melt processing to binary-component functional hybrid systems, and paves the way to solvent-free perovskite-based device fabrication.

Simulation‐Based Analysis of Environmentally Friendly Perovskite Solar Cells: Projecting 21.61% Efficiency with Lead‐Free CsSn0.5Ge0.5I3

In this study, a simulation‐based analysis of environmentally friendly, lead‐free perovskite (PVK) solar cells (PSC) with high power conversion efficiency (PCE), is presented. Various PVK materials, including lead‐, tin‐, germanium‐, and tin–germanium‐based compounds, are evaluated through simulations to explore their impact on device performance. Among these, CsSn0.5Ge0.5I3 demonstrates the highest simulated efficiency, with a rectangular cell architecture of 0.45 × 0.9 mm. Key parameters such as thickness, temperature, doping concentration, and bandgap are systematically varied in the simulations to study their effects on device performance. The optimized architecture is found to be Au/Spiro‐MeOTAD (hole‐transport layer)/CsSn0.5Ge0.5I3/TiO2 (electron‐transport layer)/FTO, achieving a simulated PCE of 21.61%, with an open‐circuit voltage (Voc) of 1.2 V, short‐circuit current density (Jsc) of 21.32 mA cm−2, and fill factor of 84.43%. Furthermore, in this study, detailed electrical simulations (electric field distribution, Shockley–Read–Hall recombination, and electron and hole concentrations) and thermal simulations (nonradiative recombination heating, joule heating) of the device are included. In this work, the potential of lead‐free PSCs is underscored and the importance of continuous simulation studies to design eco‐friendly, high‐efficiency photovoltaic devices is highlighted.

Biomass-Derived Materials in Perovskite Solar Cells: Recent Progress and Future Prospects.

As a promising photovoltaic (PV) technology, perovskite solar cells (PSCs) have made significant progress in attaining high PCE, while challenges remain regarding stability and low cost. Conventional PSCs using noble metals (e.g., Au and Ag) as back electrodes and transparent conducting oxides as front electrodes contribute significantly to their high costs. PSCs comprising biomass-derived materials, such as biocarbon as back electrodes and flexible and transparent cellulosic substrates as front electrodes, offer a promising solution to address these issues. These approaches have the potential to simultaneously improve stability and decrease manufacturing costs, making PSCs closer to commercialization. This review article furnishes a comprehensive overview of recent developments in biocarbon-based perovskite solar cells (C-PSCs), focusing on various biomass-derived biocarbon materials utilized as back electrodes in different C-PSCs device structures. This article also compiles the advancement of flexible and transparent cellulosic substrate-based PSCs by highlighting the fundamentals of PSC and C-PSC architectures, the basics of biomass, and the synthesis of biocarbon. Finally, this review discusses the current challenges and future research directions for optimizing biocarbon materials and cellulosic substrates in PSC technology.

A facile approach for fabricating efficient and stable perovskite solar cells.

Perovskite solar cells (PSCs) with high power conversion efficiencies (PCEs) can be produced using a variety of methods, such as different fabrication methods, device layout modification, and component and interface engineering. The efficiency of a perovskite solar cell is largely dependent on the overall quality of the perovskite thin-film in every scenario. The utilization of spin-coating followed by the antisolvent pouring (ASP) method is prevalent in nearly all fabrication techniques to achieve superior perovskite thin-films. Nevertheless, there are a few guidelines that must be followed precisely when using the ASP approach, including the antisolvent amount, duration, and area for dropping. The aforementioned challenging and necessary strategies frequently result in perovskite thin-films with pinholes, tiny grains, and broad grain boundaries, which impair the performance of PSCs. Therefore, the implementation of a straightforward approach that does not require the use of such complex ASP steps is crucial. Here, we employ a simple process that involves the hot-dipping of lead iodide (PbI2) thin-films in a hot solution of methylammonium iodide (MAI) and formamidinium iodide (FAI) in isopropanol (IPA) to produce high-quality perovskite thin-films. As the time required for the desired perovskite to crystallize is critical, we carefully examined various hot-dipping process times, such as 10 seconds, 20 seconds, 30 seconds, and 40 seconds. These time intervals yielded thin-films, which were named PSK-10, PSK-20, PSK-30, and PSK-40, respectively. Morphological and optoelectronic characterization demonstrated the high quality of the perovskite thin-films obtained through dipping PbI2 for 30 seconds. Consequently, the PSK-30-based PSCs produced higher PCEs of up to 21.52% compared to those of the ASP-based devices (20.79%). Furthermore, the unsealed PSCs prepared with PSK-30 and ASP were assessed for 252 hours at 25 °C and 40-45% relative humidity in order to determine their operational stability. The ASP-based device showed poor stability, retaining only 10% of its original PCE, whereas the PSK-30-based device retained 70% of its initial PCE. These results offer a new and viable approach for producing highly efficient and stable PSCs.

Light‐Driven Dynamic Defect‐Passivation for Efficient Inorganic Perovskite Solar Cells

AbstractDue to its soft lattice characteristics, all‐inorganic cesium lead halide (CsPbI3‐xBrx) perovskite is vulnerable to external environmental stress such as moisture, polar solvent, illumination. resulting in structural defects (VI, Ii, etc.) and ion mobility. However, most of the prior arts focus on short‐term and static passivation, which has a negligible effect on defects formed during solar cell operation. Herein, a photoisomerizable molecule, 1,3,3‐trimethylindolino‐8′‐methoxybenzopyrylospiran (OMe‐SP), exhibiting light‐driven pre‐isomeric (SP) and post‐isomeric (PMC) configurations, is employed as an interfacial protective layer on top of CsPbI3‐xBrx. The present strategy not only effectively suppresses migration of halogen ions, but also enables sustainable passivation of defects, thereby significantly reducing interfacial charge recombination and retarding perovskite degradation. Consequently, the OMe‐SP‐modified perovskite solar cells (PSCs) exhibit superior stability, maintaining 91% of their initial efficiency after aging 1032 h under maximum power point (MPP) tracking and continuous one sun illumination. Meanwhile, the OMe‐SP‐modified cell also achieves an impressive power conversion efficiency of 22.20%, which stands as the highest among all‐inorganic perovskite solar cells. Overall, the implementation of this robust strategy provides sustainable defect passivation and continuous suppression of ion migration for achieving both high PCE and stable inorganic perovskite.

Visualizing Performances Losses of Perovskite Solar Cells and Modules: From Laboratory to Industrial Scales

AbstractWhile the efficiencies of lab‐sized perovskite solar cells are continuously rising, a variety of challenges have to be overcome to realize remotely similar efficiencies in an industrial context. Any changes in the preparation process, device size, device architecture, and material type are likely to result in efficiency loss. To date, there have been no solutions that can produce large‐area modules with performance comparable to that of laboratory devices. However, depending on the type of deposition process, the dominant loss mechanisms differ significantly, which can guide the further optimization of processes and devices. In this study, a meta‐analysis of state‐of‐the‐art perovskite solar cells and modules with different preparation methods, area sizes, and material compositions, is presented. Moreover, the efficiency losses are divided into five figures of merit and they are visualized to discuss the efficiency‐limiting loss mechanisms that must be overcome for commercialization.

Halide-Diffusion-Assisted Perovskite Lamination Process for Semitransparent Perovskite Solar Cells.

Semitransparent perovskite solar cells (PSCs) efficiently absorb light from both front and rear sides under illumination, and hence, PSCs have the potential for use in applications requiring bifacial or tandem solar cells. A facile method to fabricate semitransparent PSCs involves preparing a perovskite (PVSK) film on two transparent substrates and then laminating the substrates together. However, realizing high-performance laminated semitransparent PSCs is challenging because the imperfect contact at the PVSK interlayer results in void formation and partial degradation of PVSK. To address this issue, a halide-diffusion-assisted lamination (HDL) method is proposed. In the method, a controlled halide concentration gradient is used to effectively laminate the top and bottom PVSK layers. Semitransparent PSCs prepared through the HDL method (hereafter referred to as HDL-PSCs) exhibited a power conversion efficiency (PCE) of 18.93%. In particular, an HDL-PSC exhibited higher thermal stability, maintaining its initial PCE for over 1200h at 85°C.

Stabilization Strategies of Buried Interface for Efficient SAM-based Inverted Perovskite Solar Cells.

In recent years, self-assembled monolayers (SAMs) anchored on metal oxides (MO) have greatly boosted the performance of inverted (p-i-n) perovskite solar cells (PVSCs) by serving as hole-selective contacts due to their distinct advantages in transparency, hole-selectivity, passivation, cost-effectiveness, and processing efficiency. While the intrinsic monolayer nature of SAMs provides unique advantages, it also makes them highly sensitive to external pressure, posing a significant challenge for long-term device stability. At present, the stability issue of SAM-based PVSCs is gradually attracting attention. In this review, we discuss the fundamental stability issues arising from the structural characteristics, operating mechanisms, and roles of SAMs, and highlight representative works on improving their stability. We identify the buried interface stability concerns in three key aspects: 1) SAM/MO interface, 2) SAM inner layer, and 3) SAM/perovskite interface, corresponding to the anchoring group, linker group, and terminal group in the SAMs, respectively. Finally, we have proposed potential strategies for achieving excellent stability in SAM-based buried interfaces, particularly for large-scale and flexible applications. We believe this review will deepen understanding of the relationship between SAM structure and their device performance, thereby facilitating the design of novel SAMs and advancing their eventual commercialization in high-efficiency and stable inverted PVSCs.