Moisture-Resilient Perovskite Solar Cells for Enhanced Stability

Buried Interface Regulation with a Supramolecular Assembled Template Enables High-Performance Perovskite Solar Cells for Minimizing the VOC Deficit

Despite the rapid development of perovskite solar cells (PSCs) in the past decade, the open-circuit voltage (VOC) of PSCs still lags behind the theoretical Shockley-Queisser limit. Energy-level mismatch and unwanted nonradiative recombination at key interfaces are the main factors detrimental to VOC. Herein, a perovskite crystallization-driven template is constructed at the SnO2/perovskite buried interface through a self-assembled amphiphilic phosphonate derivative. The highly oriented supramolecular template grows from an evolutionary selection growth via solid-solid phase transition. This strategy induces perovskite crystallization into a highly preferred (100) orientation toward out-of-plane direction and facilitated carrier extraction and transfer due to the elimination of energy barrier. This self-assembly process positively passivates the intrinsic surface defects at the SnO2/perovskite interface through the functionalized moieties, a marked contrast to the passive effect achieved via incidental contacts in conventional passivation methods. As a result, PSCs with buried interface modification exhibit a promising PCE of 25.34%, with a maximum VOC of 1.23 V, corresponding to a mere 0.306 V deficit (for perovskite bandgap of 1.536 eV), reaching 97.2% of the theoretical VOC limit. This strategy spontaneously improves the long-term operational stability of PSCs under thermal and moisture stress (ISOS-L-3: MPP, 65 °C, 50% RH, T92 lifetime exceeding 1200 h).

Hole-selective Transparent In Situ Passivation Contacts for Efficient and Stable n-i-p Graded Perovskite/Silicon Tandem Solar Cells

The optically deficient and intrinsically unstable hole transport layer (HTL) is the Achilles' heel of n-i-p perovskite/silicon tandems. Here, a minimalist transparent hole-selective contact is developed without additional HTL by simply integrating cross-linkable p-type small molecules into antisolvent. This strategy not only improves the perovskite crystallinity, shields the perovskite from external stressors, and suppresses interfacial mass exchange, but also provides efficient defect passivation and favorable band alignment via the formation of graded heterojunction. Consequently, the corresponding 1.65 eV perovskite solar cell achieves a stabilized efficiency of 19.6%, alongside significantly improved thermal, ultraviolet, and operation stabilities. Furthermore, leveraging its outstanding transparency, a bifacial single-junction device is showcased achieving a record bifaciality of 101.4%, and a monolithic perovskite/silicon tandem boasting a certified efficiency of 29.2% for 1.04 cm2, which represents the highest certified efficiency achieved for n-i-p perovskite/silicon tandems. The demonstration of efficient and stable minimalist hole-selective contacts encourages the tandem community to reevaluate the n-i-p structure, with the goal of harnessing the high open-circuit voltage of single-junction n-i-p PSCs.

Architectural Innovations in Perovskite Solar Cells

Meeting future energy demands with sustainable sources like photovoltaics (PV) presents significant land and logistical challenges, which can be mitigated by improving PV power conversion efficiency (PCE) and decentralized solutions like building-integrated photovoltaics and solar-integrated mobility systems (e.g., Unmanned Aerial Vehicles (UAVs)). Metal Halide Perovskites Solar Cells (MH-PSCs) provide a transformative, low-cost solution for high-efficiency PV with diverse compositions, exceptional optoelectronic properties, and low-temperature, solution-based processability. Conventionally the MH-PSCs are fabricated in "p-i-n" or "n-i-p" configuration on glass-Transparent Conductive Oxide (TCO) substrates. While glass-based Perovskite Solar Cells (PSCs) have achieved remarkable efficiencies, their limited scalability, high areal-weight, and mechanical rigidity greatly limit their usage in wearables electronics, BIPVs, and e-mobility applications. Addressing these challenges requires "targeted architectural innovations" in MH-PSCs, tailored to specific applications, to drive their practical deployment forward. This study reviews four innovative PSC architectures-Interdigitated Back Contact (IBC) PSCs, Lateral Configuration (LC) PSCs, Fiber-Shaped (FS) PSCs, and Substrate-Configuration (SC) PSCs-highlighting their design advancements for enhanced efficiency, flexibility, lightweight, and application-specific integration. Importantly, the review discusses the precise engineering required in each layer of these architectural innovations to ensure compatibility, efficient charge transport, durability, and scalability while optimizing performance, while also identifying key challenges and outlining directions for future R&D.

Multilength-Scale Morphological Engineering for Stable Organic Solar Cells

Organic solar cells (OSCs) have garnered significant attention owing to the light weight, flexibility, and low cost. Continuous improvement in molecular design, morphology control, and device fabrication has propelled the power conversion efficiency of OSCs beyond 20%. While obtaining long-term device stability is still a critical obstacle for the commercialization of OSCs. The nano- and microstructural characteristics of the active layer morphology-including molecular stacking, phase separation, and domain sizes-play a pivotal role in determining device performance. Consequently, a comprehensive understanding of how film structure impacting device stability and the methods to control film morphology are vital for improving device lifetime. This review seeks to elucidate the structure-performance relationship between active layer morphology from the nanoscale to microscale and device stability. It can provide rational guidance to enhance device stability from morphology control, accelerating the commercialization of OSCs.

Pressure Engineering to Enable Improved Stability and Performance of Metal Halide Perovskite Photovoltaics

In this work, we demonstrate that an external pressure of 15-30 kPa can significantly improve metal halide perovskite (MHP) film thermal stability. We demonstrate this through the application of weight on top of an MHP film during thermal aging in preserving the perovskite phase and the mobile ion concentration, an effect which we hypothesize reduces the extent to which volatile species can escape from the MHP lattice. This method is shown to be effective for a more scalable approach by only applying the weight to a cover glass during the lamination of an epoxy-based resin, after which the weight is removed. The amount of pressure applied during lamination is shown to correlate with stability in both 1 sun illumination and damp heat testing. Lastly, the performance of MHP photovoltaic devices is improved using pressure during lamination, an effect which is attributed to improved interfacial contact between the MHP and the adjacent charge transport layers and healing of any voids or defects that may exist at the buried interface after processing. As such, there are implications for tuning the amount of pressure that is applied during lamination to enable the durability of MHP solar modules toward manufacturing-scale deployment.

Powering the Future: Opportunities and Obstacles in Lead-Halide Inorganic Perovskite Solar Cells

Efficiency, stability, and cost are crucial considerations in the development of photovoltaic technology for commercialization. Perovskite solar cells (PSCs) are a promising third-generation photovoltaic technology due to their high efficiency and low-cost potential. However, the stability of organohalide perovskites remains a significant challenge. Inorganic perovskites, based on CsPbX₃ (X = Br-/I-), have garnered attention for their excellent thermal stability and optoelectronic properties comparable to those of organohalide perovskites. Nevertheless, the development of inorganic perovskites faces several hurdles, including the need for high-temperature annealing to achieve the photoactive α-phase and their susceptibility to transitioning into the nonphotoactive δ-phase under environmental stressors, particularly moisture. These challenges impede the creation of high-efficiency, high-stability devices using low-cost, scalable manufacturing processes. This review provides a comprehensive background on the fundamental structural, physical, and optoelectronic properties of inorganic lead-halide perovskites. It discusses the latest advancements in fabricating inorganic PSCs at lower temperatures and under ambient conditions. Furthermore, it highlights the progress in state-of-the-art inorganic devices, particularly those manufactured in ambient environments and at reduced temperatures, alongside simultaneous advancements in the upscaling and stability of inorganic PSCs.

Nanocrystalline Perovskites for Bright and Efficient Light-Emitting Diodes

Nanocrystalline perovskites have driven significant progress in metal halide perovskite light-emitting diodes (PeLEDs) over the past decade by enabling the spatial confinement of excitons. Consequently, three primary categories of nanocrystalline perovskites have emerged: nanoscale polycrystalline perovskites, quasi-2D perovskites, and perovskite nanocrystals. Each type has been developed to address specific challenges and enhance the efficiency and stability of PeLEDs. This review explores the representative material design strategies for these nanocrystalline perovskites, correlating them with exciton recombination dynamics and optical/electrical properties. Additionally, it summarizes the trends in progress over the past decade, outlining four distinct phases of nanocrystalline perovskite development. Lastly, this review addresses the remaining challenges and proposes a potential material design to further advance PeLED technology toward commercialization.

A Versatile Ionic Liquid Additive for Perovskite Solar Cells: Surface Modification, Hole Transport Layer Doping, and Green Solvent Processing

Hole-transport layers (HTL) in perovskite solar cells (PSCs) with an n-i-p structure are commonly doped by bis(trifluoromethane)sulfonimide (TFSI) salts to enhance hole conduction. While lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopant is a widely used and effective dopant, it has significant limitations, including the need for additional solvents and additives, environmental sensitivity, unintended oxidation, and dopant migration, which can lead to lower stability of PSCs. A novel ionic liquid, 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (MMPyTFSI), is explored as an alternative dopant for 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD). MMPy ions act as a surface passivator, reducing defects on the perovskite surface, while TFSI ions facilitate p-type doping. MMPyTFSI functions as an efficient dopant, maintaining excellent performance even when tetrahydrofuran (THF) is utilized as a solvent in place of chlorobenzene (CB), while significantly reducing the environmental impact of the process. The optimized PSC achieves a power conversion efficiency (PCE) of 23.10% and demonstrates enhanced long-term stability in all aging tests for over 1000 h in a humid atmosphere, at high temperature, and under simulated sunlight illumination. These results demonstrate that MMPyTFSI is an effective and environmentally friendly dopant for producing stable and efficient PSCs.

High Relative Humidity-Induced Growth of Perovskite Nanowires from Glass toward Single-Mode Photonic Nanolasers at Sub-100-nm Scale

Metal halide perovskites (MHPs) have achieved substantial progress in their applications; however, their ionic crystal character and low formation energy result in poor structural stability and limited morphological tunability. In particular, high relative humidity (RH) commonly causes severe MHP degradation, which poses a major obstacle to long-term device operation. Herein, high RH-induced growth of anisotropic MHP structures on glass surfaces is reported under 25 °C and atmospheric conditions on a basis of glass corrosion by moisture. Nanowires (NWs) with tunable length and composition are obtained under 85% RH air, and water molecule-induced facet engineering of perovskite is established for anisotropic growth. Importantly, single-mode photonic lasing in these MHP NWs with thickness at sub-100-nm scale (down to 75 nm ∼ 1/7 lasing wavelength) is achieved via both one-photon and multiphoton pumping. These nanowire lasers exhibited high quality factor (>3000), high degree of polarization (≈0.9), and excellent stability under laser irradiation. The work not only presents a distinctive technique for the growth of MHPs but also endows MHP NWs with new opportunities for nonlinear optics, strong light-matter interactions, and active photonic integrated devices.

Solvent-dripping modulated 3D/2D heterostructures for high-performance perovskite solar cells

The controlled growth of two-dimensional (2D) perovskite atop three-dimensional (3D) perovskite films reduces interfacial recombination and impedes ion migration, thus improving the performance and stability of perovskite solar cells (PSCs). Unfortunately, the random orientation of the spontaneously formed 2D phase atop the pre-deposited 3D perovskite film can deteriorate charge extraction owing to energetic disorder, limiting the maximum attainable efficiency and long-term stability of the PSCs. Here, we introduce a meta-amidinopyridine ligand and the solvent post-dripping step to generate a highly ordered 2D perovskite phase on the surface of a 3D perovskite film. The reconstructed 2D/3D perovskite interface exhibits reduced energetic disorder and yields cells with improved performance compared with control 2D/3D samples. PSCs fabricated with the meta-amidinopyridine-induced phase-pure 2D perovskite passivation show a maximum power conversion efficiency of 26.05% (a certified value of 25.44%). Under damp heat and outdoor tests, the encapsulated PSCs maintain 82% and 75% of their initial PCE after 1000 h and 840 h, respectively, demonstrating improved practical durability.

Highly stable perovskite solar cells with 0.30 voltage deficit enabled by a multi-functional asynchronous cross-linking

The primary challenge in commercializing perovskite solar cells (PSCs) mainly stems from fragile and moisture-sensitive nature of halide perovskite materials. In this study, we propose an asynchronous cross-linking strategy. A multifunctional cross-linking initiator, divinyl sulfone (DVS), is firstly pre-embedded into perovskite precursor solutions. DVS, also as a special co-solvent, facilitates intermediate-dominated perovskite crystallization manipulation, favouring formamidine-DVS based solvate transition. Subsequently, DVS-embedded perovskite as-cast films are post-treated with a nucleophilic reagent, glycerinum, to trigger controllably three-dimensional co-polymerization. The resulting cross-linking scaffold provides enhanced water-resistance, releases residual tensile strain, and suppresses deep-level defects. We achieve a maximum efficiency over 25% (certified 24.6%) and a maximum VOC of 1.229 V, corresponding to mere 0.30 V deficit, reaching 97.5% of the theoretical limit, which is the highest reported in all perovskite systems. This strategy is generally applicable with enhanced efficiencies approaching 26%. All-around protection significantly improves PSC's operational longevity and thermal endurance.

Crystal structure of catena-poly[bis-(N,O-di-methyl-hydroxyl-ammonium) [di-μ-bromido-di-bromido-stannate(II)]]

The title compound, {(C2H8NO)2[SnBr4]} n , is a layered hybrid perovskite crystallizing in the monoclinic space group C2/c. The asymmetric unit consists of one H3C-O-NH2 +-CH3 cation (Me2HA+), one SnII atom located on a twofold rotation axis, and two Br atoms. The SnII atom has a distorted octa-hedral coordination environment formed by the bromido ligands. The {SnBr6} units corner-share their equatorial Br atoms, forming infinite mono-layers that extend parallel to the ab plane. These inorganic layers are sandwiched by the organic Me2HA+ cations organized in double-layers; stacking of the layers is along the c-axis direction. Consecutive inorganic layers, separated by the organic cations, are shifted relative to each other along the b-axis direction. Specifically, the SnII atom in one inorganic layer is offset by 3.148 Å along the b axis relative to the SnII atom in an adjacent inorganic layer. The N,O-di-methyl-hydroxyl-ammonium cation forms two hydrogen bonds with the axial bromide anions of the inorganic layers as acceptors, and leads to the cohesion of the crystal structure. According to Hirshfeld surface analysis, the highest contributions to the crystal packing are from H⋯H (46.2%), Br⋯H (38.5%), and H⋯O (14.8%) contacts.

Modelling and Numerical Evaluation of Photovoltaic Parameters of a Highly Efficient Perovskite Solar Cell Based on Methylammonium Tin Iodide

Designing a high-performance solar cell structure requires the understanding of material innovation, device engineering, charge behavior, operation characteristics and efficient photoconversion of light to generate electricity. This study offers a detailed numerical evaluation of the device physics in a highly efficient methylammonium-based perovskite solar cell (PSC) of the configuration, FTO/WO3/CH₃NH₃SnI₃/GO/Fe. Utilizing the SCAPS-1D device simulator, an impressive open-circuit voltage (Voc) of 1.3184 V, short-circuit current density (Jsc) of 35.10 mA/cm2, Fill factor (FF) of 78.38 %, and power conversion efficiency (PCE) of 36.24 % were achieved. The model cell exhibits a robust photon capture of 100 % quantum efficiency between 360 and 750 nm. The study also presents a temperature-dependent band alignment diagram which posted a built-in potential (Vbi) of 0.62 eV. The Vbi at 400 K was found to be 0.58 eV indicating that the model cell exhibits a decent temperature tolerance, and can retain approximately 93 % of its power at 400 K. Through Mott-Schottky capacitance analysis, deeper insights into the space-charge region are inferred, while recombination-generation investigations emphasize the significance of electronic properties in optimizing device performance. This paper, therefore, lays the foundation for future studies, offering clear pathways for device optimization and identifying key areas that require further investigation.

Tetrabutylammonium Hydroxide-Functionalized Ti3C2Tx MXene for Significantly Improving the Photovoltaic Performance of Perovskite Solar Cells

An appropriate electron transport layer (ETL) or cathode buffer layer (CBL) is critical for high-performance perovskite solar cells (PVSCs). In this work, tetrabutylammonium hydroxide (TBAOH)-functionalized Ti3C2Tx MXene (TBAOH-Ti3C2Tx) is developed to improve the photovoltaic performance of PVSCs. TBAOH-Ti3C2Tx is synthesized by HF etching and then TBAOH intercalation, and TBAOH can effectively attach to the Ti3C2Tx surface during the intercalation process. In hole transport material (HTM)-free carbon-based PVSCs with the structure of ITO/ETL/MAPbI3/carbon, the SnO2 doped by TBAOH-Ti3C2Tx (SnO2:TBAOH-Ti3C2Tx) as ETL shows decreased WF and increased conductivity and improves the growth of the perovskite film with a larger grain and significantly reduced defects, which synergistically facilitate charge transport and extraction and reduce charge recombination. The HTM-free carbon-based PVSC with SnO2:TBAOH-Ti3C2Tx ETL exhibits a significantly higher PCE of 14.93% with enhanced device stability compared to the control device with pristine SnO2 ETL (11.95%) and also outperforms most of the HTM-free carbon-based PVSCs with MAPbI3 perovskite reported so far. In traditional inverted PVSCs with the structure of ITO/PTAA/MAPbI3/PCBM/CBL/Ag, the TBAOH-Ti3C2Tx is utilized as a CBL to significantly enhance device performance with a high PCE of 21.16%, which is obviously superior than that (16.26%) of the control device without CBL. The impressive results indicate that tetrabutylammonium hydroxide-functionalized Ti3C2Tx MXene possesses great application potential in different functional layers for high-performance PVSCs.

Pseudohalide-Based Ionic Liquids: Advancing Crystallization Kinetics and Optoelectronic Properties in All-Inorganic Perovskite Solar Cells

This study delves into the innovative approach of enhancing the efficiency and stability of all-inorganic perovskite solar cells (I-PSCs) through the strategic incorporation of thiocyanate (SCN-) ions via pseudohalide-based ionic liquid (IL) configurations. This straightforward methodology has exhibited captivating advancements in the kinetics of crystallization as well as the optoelectronic characteristics of the resulting perovskite films. These developments hold the promise of enhancing not only the quality and uniformity of the films but also aspects such as band alignment and the efficacy of charge transfer mechanisms. Calculation results corroborate that the incorporation of 1-butyl-3-methylimidazolium thiocyanate (BmimSCN) led to a significant redistribution of electron state density and enhanced electron-donating properties, indicating a substantial electron transfer between the perovskite material and the IL. Notably, the engineered devices demonstrate a remarkable efficiency surpassing 15%, a substantial enhancement attributed to the synergistic effects of the SCN- ion. Additionally, this approach offers inherent stability benefits, thereby addressing a significant challenge in I-PSC technology. This IL maintains >90% of the initial efficiency after 600 h, while the control device decreased to <20% of its initial value after only 100 h. 1-butyl-3-methylimidazolium iodide (BmimI) is also employed to further investigate the effects of SCN- ions on device performance.

In-situ synthesized perovskite/polyhedral oligomeric silsesquioxane nanocomposites for robust X-ray imaging

Perovskites are extensively studied in scintillation detection due to their low cost, simple synthesis, high scintillation light yield, and rapid decay times. However, their instability to light and radiation leads to scintillation performance degradation. To address these stability concerns, this paper proposes a new perovskite nanocrystal (NC) synthesis method that employs aminopropyllsobutyl polyhedral oligomeric silsesquioxane (POSS) as a ligand and a coating layer to passivate the perovskite NCs, significantly enhancing their stability and photoluminescence efficiency. Furthermore, the resultant perovskite/aminopropyllsobutyl POSS nanocomposites exhibit remarkable capabilities in X-ray detection limits, imaging quality, and radiation hardness. These findings underscore the potential of enhanced perovskite in revolutionizing the field of scintillator materials, offering promising pathways for their future applications and development.

Towards the 10-Year Milestone of Monolithic Perovskite/Silicon Tandem Solar Cells

The perovskite/silicon tandem solar cell represents one of the most promising avenues for exceeding the Shockley-Queisser limit for single-junction solar cells at a reasonable cost. Remarkably, its efficiency has rapidly increased from 13.7% in 2015 to 34.6% in 2024. Despite the significant research efforts dedicated to this topic, the "secret" to achieving high-performance perovskite/silicon tandem solar cells seems to be confined to a few research groups. Additionally, the discrepancies in preparation and characterization between single-junction and tandem solar cells continue to impede the transition from efficient single-junction to efficient tandem solar cells. This review first revisits the key milestones in the development of monolithic perovskite/silicon tandem solar cells over the past decade. Then, a comprehensive analysis of the background, advancements, and challenges in perovskite/silicon tandem solar cells is provided, following the sequence of the tandem fabrication process. The progress and limitations of the prevalent stability measurements for tandem devices are also discussed. Finally, a roadmap for designing efficient, scalable, and stable perovskite/silicon tandem solar cells is outlined. This review takes the growth history into consideration while charting the future course of perovskite/silicon tandem research.

Transforming Plain LaMnO3 Perovskite into a Powerful Ozonation Catalyst: Elucidating the Mechanisms of Simultaneous A and B Sites Modulation for Enhanced Toluene Degradation

Herein, we propose preferential dissolution paired with Cu-doping as an effective method for synergistically modulating the A- and B-sites of LaMnO3 perovskite. Through Cu-doping into the B-sites of LaMnO3, specifically modifying the B-sites, the double perovskite La2CuMnO6 was created. Subsequently, partial La from the A-sites of La2CuMnO6 was etched using HNO3, forming novel La2CuMnO6/MnO2 (LCMO/MnO2) catalysts. The optimized catalyst, featuring an ideal Mn:Cu ratio of 4.5:1 (LCMO/MnO2-4.5), exhibited exceptional catalytic ozonation performance. It achieved approximately 90% toluene degradation with 56% selectivity toward CO2, even under ambient temperature (35 °C) and a relatively humid environment (45%). Modulation of A-sites induced the elongation of Mn-O bonds and decrease in the coordination number of Mn-O (from 6 to 4.3) in LCMO/MnO2-4.5, resulting in the creation of abundant multivalent Mn and oxygen vacancies. Doping Cu into B-sites led to the preferential chemisorption of toluene on multivalent Cu (Cu(I)/Cu(II)), consistent with theoretical predictions. Effective electronic supplementary interactions enabled the cycling of multiple oxidation states of Mn for ozone decomposition, facilitating the production of reactive oxygen species and the regeneration of oxygen vacancies. This study establishes high-performance perovskites for the synergistic regulation of O3 and toluene, contributing to cleaner and safer industrial activities.

Key Roles of Interfaces in Inverted Metal-Halide Perovskite Solar Cells

Metal-halide perovskite solar cells (PSCs), an emerging technology for transforming solar energy into a clean source of electricity, have reached efficiency levels comparable to those of commercial silicon cells. Compared with other types of PSCs, inverted perovskite solar cells (IPSCs) have shown promise with regard to commercialization due to their facile fabrication and excellent optoelectronic properties. The interlayer interfaces play an important role in the performance of perovskite cells, not only affecting charge transfer and transport, but also acting as a barrier against oxygen and moisture permeation. Herein, we describe and summarize the last three years of studies that summarize the advantages of interface engineering-based advances for the commercialization of IPSCs. This review includes a brief introduction of the structure and working principle of IPSCs, and analyzes how interfaces affect the performance of IPSC devices from the perspective of photovoltaic performance and device lifetime. In addition, a comprehensive summary of various interface engineering approaches to solving these problems and challenges in IPSCs, including the use of interlayers, interface modification, defect passivation, and others, is summarized. Moreover, based upon current developments and breakthroughs, fundamental and engineering perspectives on future commercialization pathways are provided for the innovation and design of next-generation IPSCs.

Double-side 2D/3D heterojunctions for inverted perovskite solar cells

Defects at the top and bottom interfaces of three-dimensional (3D) perovskite photoabsorbers diminish the performance and operational stability of perovskite solar cells owing to charge recombination, ion migration and electric-field inhomogeneities1-5. Here we demonstrate that long alkyl amine ligands can generate near-phase-pure 2D perovskites at the top and bottom 3D perovskite interfaces and effectively resolve these issues. At the rear-contact side, we find that the alkyl amine ligand strengthens the interactions with the substrate through acid-base reactions with the phosphonic acid group from the organic hole-transporting self-assembled monolayer molecule, thus regulating the 2D perovskite formation. With this, inverted perovskite solar cells with double-side 2D/3D heterojunctions achieved a power conversion efficiency of 25.6% (certified 25.0%), retaining 95% of their initial power conversion efficiency after 1,000 h of 1-sun illumination at 85 °C in air.