Flexible kesterite Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaics are attractive for lightweight and portable applications, but their efficiency remains limited by uncontrolled alkali-metal incorporation. Here we elucidate and exploit the distinct and complementary roles of Na and Li in controlling CZTSSe crystallization on flexible substrates. Our results show that Na promotes crystal growth, but its induced Se enrichment simultaneously drives large-scale SnSex phase segregation. The incorporation of Li reshapes the free-energy landscape of Cu-related phases, promoting the formation of CuxSe that consumes Se and thereby suppressing SnSex phase growth while driving ordered phase evolution. This kinetic competition strategy yields high-quality CZTSSe films with reduced charge recombination loss and enables power conversion efficiencies of 14.5% (certified 14.2%) for flexible cells and 12.7% (certified 12.0%) for shingled modules. Our results provide mechanistic insights into alkali-metal regulation in chalcogenide solar cells and demonstrate a kinetic competition strategy that can be generalized to regulate crystallization in complex multinary materials.

Flexible perovskite solar cells (F-PSCs) exhibit much wider application scope due to the advantages of being light weight, portable, bendable, compatible with curved surfaces, etc. However, unsatisfactory efficiency and mechanical stability severely restrain their further development. Here, an interfacial adhesion strategy is reported to improve the mechanical stability of n-i-p-type F-PSCs. Poly-ECA is inserted between the perovskite layer and SnO2 layer by the self-polymerization of ethyl alpha-cyanoacrylate (ECA) under mild conditions. Strong interactions between poly-ECA and the SnO2/perovskite layer can enhance the mechanical strength of the buried interface. In addition, interfacial defects are also passivated and the energy level alignment at the perovskite interface bottom is optimized, thus facilitating charge transportation. Based on this interfacial adhesion strategy, 25.7% PCE has been achieved with a certified PCE of 25.04% for small-area flexible PSC devices, and 21.9% PCE has been obtained for large-area F-PSC modules (aperture area: 22.55 cm2). Additionally, device stability, particularly mechanical stability, has been significantly improved, and 95% of the initial efficiency can be maintained by small-area devices after 10 000 bending cycles. This work provides a simple, convenient way to simultaneously enhance the efficiency and stability of flexible devices.

ABSTRACT Interfacial engineering has been widely used to reduce interfacial non‐radiative recombination and enhance the performance of perovskite solar cells (PSCs), but stability issue of interfacial passivation itself has been seldom explored. Herein, we design two halide imidazolium‐based molecules with halogen octyl chains (X8C‐mImX, X = Br, I) for n‐i‐p typed PSCs. It is found that 2D/3D heterojunction structure based on substituted imidazolium cations is formed at the perovskite/spiro‐OMeTAD interface, which effectively passivates interface defects. Meanwhile, free Br − and I − ions can passivate iodide‐vacancy‐related defects at the interfaces, while Br − ions can further contribute to defect passivation in the bulk. With the synergistic effects of the mixed I8C‐mImI/Br8C‐mImBr (I/Br‐mIm), small‐area PSC device presents 26.33% efficiency with negligible hysteresis. Typically, the 2D phase (I/Br‐mIm) 2 PbI 4 , exhibits excellent thermal stability to guarantee the stability of the interface passivation. Accordingly, modified devices exhibit better thermal stability by maintaining 92% of initial efficiency after 1200 h at 85°C. The devices also retain 90% of initial efficiency after 1000 h continuous illumination with a bias voltage close to maximum power point (MPP), indicating its good operational stability. This work provides a feasible way to enhance interface stability and overall device stability by selecting suitable post‐treatment materials.

Targeting at high quality FAPbI(3) films and efficient FAPbI(3) perovskite solar cells, simultaneously regulating perovskite crystal growth and passivating defects from the bulk and interfaces are particularly important. In this respect, we designed two imidazolium-based additives (ImXBr-BF4, X = 8, 12) with different bromoalkyl chain length for n-i-p typed PSCs. Based on experimental and theoretical calculation, Im8Br-BF4 with its optimal chain length enables the formation of ordered layered 2D perovskite. Further investigation revealed that, to the Im8Br-BF4 treated PSCs, as-formed 2D perovskite ((Im8Br)(2)PbI4) mainly at grain boundaries, can well passivate lead-related defects, in the meantime, the Br- from bromoalkyl group also passivated iodide vacancies in the bulk. Besides, the BF4- anions were contributed to partial interfacial passivation toward the buried interface. Consequently, devices with Im8Br-BF4 presented the 26.2 % PCE (0.076 cm(2)), outperforming those devices with Im12Br-BF4. And the devices also exhibited exceptional humidity stability, retaining > 90 % of its initial efficiency after 1000 h at 60 degrees C/60 %RH without encapsulation. Our multi-dimensional passivation strategy provided a simple and feasible way to enhance the device performance of PSCs.

Environmentally benign and earth-abundant kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have advanced rapidly through solution-based processing. However, scaling from laboratory-scale devices to modules remains a major challenge, largely because complex coordination networks in the precursors hinder the formation of uniform large-area films. Here we show that molecular-level regulation of metal-organic coordination can suppress the formation of cross-linked networks in precursor solutions, promoting efficient solvent removal and uniform selenization and crystallization. This coordination-controlled strategy enables the blade coating of highly homogeneous films over 10 cm2, realizing certified efficiencies of 14.2% for 1 cm2 cells and 13.0% for 10.5 cm2 modules, representing a leap-forward improvement in scalable kesterite photovoltaics. Beyond performance, the provided molecular insights into kesterite solution chemistry facilitate establishing a scalable and low-cost route towards industrial deployment of this thin-film solar technology.

The performance of kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells is critically governed by the quality of the CZTSSe/CdS heterojunction; however, the morphology, crystallinity, and defect landscape of CdS buffer layers are intrinsically constrained by the inevitable competition between homogeneous and heterogeneous nucleation in widely used chemical bath deposition (CBD). Here, we report a simple yet effective surface microstructural reconstruction strategy based on chemical polishing that overcomes these challenges beyond the reach of conventional CBD process regulation. Specifically, polishing CZTSSe/CdS films with a Na2S/thiourea aqueous solution selectively removes low-quality CdS particulates while inducing surface recrystallization and sulfur-vacancy compensation. As a result, the CdS films exhibit markedly improved microstructure, enhanced crystallinity, and more homogeneous surface electrical properties. Benefiting from suppressed interfacial charge recombination and accelerated charge transport, kesterite solar cells achieve a champion efficiency of 15.3% with a high open-circuit voltage (VOC) of 560 mV and a record-low VOC deficit (Eg/e-VOC) of < 0.5 V, significantly advancing kesterite photovoltaics toward low voltage loss. Moreover, this work establishes a broadly applicable post-deposition paradigm for improving CBD-CdS-based optoelectronic devices across a wide range of material systems and applications.

Precise control of point defects is imperative for enhancing the performance of emerging kesterite solar cells, yet remains challenging in the multinary Cu2ZnSn(S,Se)4 (CZTSSe) due to its complex defect chemistry. Here, guided by the correlation between phase-evolution kinetics and defect formation, we identify that the delayed formation of Cu2SnSe3 (CTSe) relative to ZnSe during selenization promotes Zn-related antisite defects, including SnZn and CuZn. To rebalance these competing phases, we develop a sodium-activated selenization strategy by pre-constructing reactive Na-Sex species and introducing them into the selenization process. This approach accelerates CTSe formation at lower temperatures, drives the synergistic ZnSe-CTSe transformation toward the CZTSSe phase, and effectively suppresses defect generation. Consequently, a certified power conversion efficiency of 15.1% is achieved with substantially reduced voltage loss, surpassing the commercialization threshold and opening opportunities for scalable inorganic photovoltaics.

To CsPbI3 perovskite solar cells, defects from buried interfaces and improper energy band alignment can cause severe carrier recombination and hamper further enhancement in efficiency and stability. In this work, we develop an in situ strategy to reconstruct the buried interface for n-i-p typed CsPbI3 solar cells. This strategy is derived from an in situ exchange reaction between 18C6/Cs+ and Pb2+, leading to the formation of 18C6/Pb2+ in the CsPbI3 crystallization process (18C6: 18-crown-6 ether). The as-prepared 18C6/Pb2+ complex acts as a kind of molecular barrier to modify the TiO2/perovskite buried interface and passivate under-coordinated Pb2+ and iodide vacancies. Additionally, free Br- ions can diffuse into the lattice of the CsPbI3 film bottom, forming a front-surface field to further suppress carrier recombination. Based on this strategy, as high as 22.14% efficiency has been achieved, demonstrating one of the highest efficiencies of CsPbI3 perovskite solar cells to date. Besides, the modified cell can maintain 95% of its initial efficiency after 1500 h of MPP testing and 1500 h of long-term stability testing, exhibiting excellent operational stability.

The interface contact issue, surface defects, and energy level mismatches have significantly limited the optoelectronic performance of solution-processed transparent conductive window layers for use in thin-film solar cells. In this work, these challenges are systematically addressed by employing molecular engineering to regulate the multiple interfaces of ZnO nanoparticles (ZnO-nps)/silver nanowires (AgNWs) window layers in kesterite solar cells. The interface molecular engineering enhances the conformal deposition of ZnO-nps on rough Cu2ZnSn(S, Se)4 (CZTSSe)/CdS substrates, passivates hydroxyl defects in ZnO-nps, and optimizes energy level alignment at the ZnO-nps/AgNWs interface. These advancements enable us to achieve a certified total area efficiency of 14.3%, marking a significant milestone for all-solution-processed kesterite solar cells. Furthermore, the solution-processed window layer forms a robust and flexion-tolerant lateral conductive network, imparting excellent flexibility to the cells. This development provides a critical technical foundation to support the low-cost and simpler preparation of thin-film solar cells in future commercialization.

CsPbI 3 perovskites with suitable bandgaps ∼1.70 eV present distinct advantages for top-cell photovoltaic materials in tandem solar cells, however, relevant work has been rarely reported. This work designed a sandwich-like MoO X /Ag/MoO X (MAM) buffer layer as the front cell window layer to maximize incident light utilization efficiency for semi-transparent CsPbI 3 solar cells and four terminal (4-T) stacked cells. Further investigation revealed that the MAM has to experience in-situ reaction between Ag metal and fresh MoO X , which can simultaneously ensure the transparency of the buffer layer and improve the carrier transportation and collection, except for protecting the underlying spiro-OMeTAD layer from the bombardment of magnetron sputtering. Thanks to this MAM buffer layer and a tunnel oxide passivating contact (TOPCon) bottom cell with edge passivation, semi-transparent CsPbI 3 devices (aperture area: 0.50 cm 2 ) demonstrated a power conversion efficiency (PCE) of 18.86% while corresponding 4-T CsPbI 3 /TOPCon tandem solar cells (PSTSCs) presented the PCE of 26.55%. Besides, we also fabricated semi-transparent CsPbI 3 minimodules with 16.67% PCE and 4-T PSTSCs with 26.41% PCE (aperture area: 6.62 cm 2 ). This work provided a new scalable strategy for transparent buffer layers by constructing in-situ generated sandwich structured buffer layer, which is suitable for perovskite tandem solar cells.

CsPbI3 perovskites with suitable bandgaps similar to 1.70 eV present distinct advantages for top-cell photovoltaic materials in tandem solar cells, however, relevant work has been rarely reported. This work designed a sandwich-like MoOX/Ag/MoOX (MAM) buffer layer as the front cell window layer to maximize incident light utilization efficiency for semi-transparent CsPbI3 solar cells and four terminal (4-T) stacked cells. Further investigation revealed that the MAM has to experience in-situ reaction between Ag metal and fresh MoOX, which can simultaneously ensure the transparency of the buffer layer and improve the carrier transportation and collection, except for protecting the underlying spiro-OMeTAD layer from the bombardment of magnetron sputtering. Thanks to this MAM buffer layer and a tunnel oxide passivating contact (TOPCon) bottom cell with edge passivation, semi-transparent CsPbI3 devices (aperture area: 0.50 cm(2)) demonstrated a power conversion efficiency (PCE) of 18.86% while corresponding 4-T CsPbI3/TOPCon tandem solar cells (PSTSCs) presented the PCE of 26.55%. Besides, we also fabricated semi-transparent CsPbI3 minimodules with 16.67% PCE and 4-T PSTSCs with 26.41% PCE (aperture area: 6.62 cm(2)). This work provided a new scalable strategy for transparent buffer layers by constructing in-situ generated sandwich structured buffer layer, which is suitable for perovskite tandem solar cells.

This review explores the role of perovskite inks and their impact on the quality of scalable perovskite films. Factors such as fluid dynamics, solvent selection, and additive engineering during the meniscus-assisted coating process are summarized.

Reducing solid fuel usage is a fundamental strategy for mitigating pollution and carbon emissions in the sintering process. Therefore, the concept of carbon-free sintering has been proposed for the first time, defined as a sintering process that does not use solid fuels. However, the role of solid fuels in addition to providing heat for sintering remains to be explained through experimental research. Therefore, the direct and indirect influences of solid fuel on sintering behavior of limonite were studied through a series of roasting experiments by changing the solid fuel content and CO reducing gas injection time, respectively. The results show that the presence of solid fuels is detrimental to the sinter quality. The mineral structure, mineral composition, and FeO content were changed due to the reaction of solid fuels with iron ore fines. As solid fuel content increases, the sinter compressive strength, reduction properties, and reduction degradation properties all exhibit a corresponding decrease. The decrease of sinter compressive strength is due to the appearance of macroporous thin-walled structure and the increase of porosity. The sinter reduction property decreases because of the decrease of hematite phase and silico ferrite of calcium and aluminum (SFCA) phase, which are easily reduced, and the increase of magnetite phase and silicate phase, which are hardly reduced. The decrease of reduction degradation index was mainly caused by the increase of secondary hematite content. In addition, the reduction gas produced by incomplete combustion of solid fuel has an effect on the quality of sinter. It results in the decrease of compressive strength and the formation of secondary hematite. In summary, the concept of carbon-free sintering is feasible, it has great potential for carbon emission reduction and pollutant emission reduction, can improve the quality of sinter, and is conducive to the formation of an ideal sintering structure.

Buried interface passivation is crucial for high-efficiency, stable perovskite solar cells (PSCs). Herein, we design a three-layer passivation structure toward the buried interface of inverted PSCs, consisting of NiOx, poly(V-p-TPD) and PFN-Br (V-p-TPD, N, N'-di-p-tolyl-N,-N'-bis (4-vinylphenyl)-[1, 1 '-biphenyl]-4, 4 '-diamine; PFN-Br, poly[(9, 9-bis(3 '-((N, N-dimethyl)-N-ethylammonium)-propyl)-2, 7-fluorene)-alt-2, 7-(9, 9-dioctylfluorene)] dibromide). Typically, in situ poly(V-p-TPD) layer on the NiOx surface was obtained by a simple thermal crosslinking process. This poly(V-p-TPD)/NiOx bilayer structure is beneficial for hole extraction and high-quality perovskite films with larger grain sizes and less lattice distortion. On this basis, the PFN-Br is further introduced as a surface modification layer, which can not only optimize the energy level alignment with the perovskite but also passivate defects and suppress carrier recombination at the perovskite bottom interface. Finally, inverted PSCs based on (FA(0.95)Cs(0.05))PbI3 present 25.5 % efficiency with a low V-OC deficit. Besides, the devices could maintain 91.15 % of the initial efficiency after being stored at 85 degrees C for 1080 h, indicating excellent thermal stability. This work highlights the potential of a three-layered passivation structure based on crosslinking polymer HTLs for highly efficient and stable PSCs. (c) 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Atomic disorder is a widespread issue in multi-element crystalline materials and poses a critical challenge to the performance of Cu2ZnSn(S, Se)4 (CZTSSe) photovoltaic devices. In particular, Cu-Zn disorder is prevalent in CZTSSe due to its low formation energy, leading to the formation of high-concentration deep defects and severe charge loss. The regulation of this disorder remains challenging because of the trade-off between the thermodynamics of the disorder-order phase transition and the kinetics of atom interchange. Here we introduce additional vacancy defects at the CZTSSe surface via magnesium doping to reduce the energy barrier for atom interchange. This vacancy-assisted approach enhances the kinetics of Cu-Zn ordering, thereby reducing charge loss in the device. As a result, we achieve a power conversion efficiency of 14.9% certified by the Chinese National PV Industry Measurement and Testing Center in CZTSSe solar cells, marking an advancement in the development of emerging inorganic thin-film photovoltaics.

Sulfide kesterite Cu2ZnSnS4 (CZTS)—a non-toxic and low-cost photovoltaic material—has always faced severe charge recombination and poor carrier transport, resulting in its cell efficiency record stagnating at around 11

Large area, dense, and uniform SnO 2 films with fewer defects are essential for high‐quality perovskite films and efficient n‐i‐p typed perovskite modules. In this respect, based on the self‐synthesized SnO 2 nanoparticles (NPs) 4,4′‐bipyridine is introduced as a multifunctional interface modifier at the SnO 2 /perovskite interface. Both experimental and DFT calculation results reveal that, the incorporation of 4,4′‐bipyridine can simultaneously passivate interfacial defects from the SnO 2 surface and perovskite bottom surface. Moreover, it can also facilitate charge carrier transportation. Based on blade‐coating technique for large area perovskite modules, this strategy significantly enhances the interfacial quality of large‐area SnO 2 films and crystal quality of large‐area perovskite layers. As a result, the champion small‐area cell (0.076 cm 2 ) presents the efficiency of 25.75% while the minimodule (22.9 cm 2 aperture area) exhibits the efficiency of 23.50% with a certified efficiency of 22.70%. Both small‐area devices and modules exhibited excellent operation and thermal stabilities, demonstrating that this interface treatment is a promising approach for large‐scale production of high‐efficiency perovskite modules.

Ambient pressure photothermal CO2 hydrogenation for producing multi-hydrocarbon (C2+: CxHy, where carbon number >1) compounds is a highly valuable way to recycle CO2 and an important path to achieve carbon neutrality. It suffers from carbon deposition during the C-C coupling process that results in low catalytic stability. To overcome this challenge, a Fe3C/ZnO heterostructure was designed to realize ambient pressure photothermal CO2 hydrogenation that can not only achieve a C2+ generation rate of similar to 1.9 mmol g(-1) h(-1), 67.9% C2+ selectivity and a CO2 conversion rate of 29.8% under natural sunlight irradiation, but also extend the stable reaction duration from 40 hours to 200 hours. In situ DRIFTS and theoretical calculations demonstrate that the Fe3C/ZnO heterostructures could significantly reduce the adsorption of CHx intermediates and activate the HCO* intermediates to regulate the C-C formation pathway of photothermal CO2 hydrogenation from the traditional CHx intermediates to HCO* and CO* intermediates, thus mitigating surface carbon deposition. This study contributes to the advancement of new catalysts designed for outdoor photothermal CO2 hydrogenation aimed at robustly producing C2+ compounds under ambient pressure.

Carbon-based perovskite solar cells exhibit a promising application prospect due to its cost effective and attractive hydrophobic nature and chemical inertness, but are still limited to unsatisfied device efficiency. Herein, we design a triple-layer full-carbon electrode for n-i-p typed perovskite solar cells, which is comprised of a modified macroporous carbon layer, a highly conductive graphite layer and a thin dense carbon layer, and each layer undertakes different contribution to improving the cell performance. Based on this full-carbon electrode, inorganic CsPbI3 perovskite solar cells exhibit >19% certified efficiency which is the highest result among carbon-based CsPbI3 devices. On one hand, carbon quantum dots decorated on the macro-porous carbon layer can realize better energy alignment of full-carbon electrode/spiro-OMeTAD/CsPbI3 interface, on the other hand, highly conductive graphite layer is advantageous to carrier transporting. Typically, the top dense carbon layer exhibits significant thermal radiation ability, which can reduce the operational temperature of devices by about 10 °C, both from theoretical simulation and experimental testing. Thereby, packaged full-carbon electrode based CsPbI3 cells exhibit much better photothermal stability at ~70°C accompanied by white light emitting diode illumination, which exhibit no efficiency degradation after 2000 h continuous operational tracking.