Zheng Zhang

Antimony selenide (Sb ₂ Se ₃ ) has emerged as a promising photovoltaic absorber owing to its suitable bandgap, high absorption coefficient, and low‐toxicity elemental composition. However, high‐efficiency Sb ₂ Se ₃ solar cells commonly rely on CdS electron‐transport layers, whereas Cd‐free alternatives often suffer from pronounced recombination losses at the Sb ₂ Se ₃ /buffer heterojunction. Herein, we introduce a sub‐nanometer atomic‐layer‐deposited aluminum oxide (Al ₂ O ₃ ) interlayer at the Sb ₂ Se ₃ /Zn _x Sn _1‐x O heterojunction to improve its interfacial electronic quality. Spectroscopic and theoretical analyses indicate that the ultrathin Al ₂ O ₃ induces interfacial chemical interaction and charge redistribution, thereby modifying the local electronic structure and interfacial energetics. Complementary surface and device‐level measurements reveal a more homogeneous near‐surface electronic response, reduced field‐dependent carrier‐collection losses, and mitigated trap‐assisted recombination. Temperature‐dependent V _OC measurements show an increase in the recombination activation energy from 0.910±0.018 to 1.045±0.021 eV, while intensity‐dependent V _OC measurements reveal a decrease in the effective ideality factor from 1.37 to 1.21, consistently indicating a reduced contribution of trap‐assisted recombination, although interface‐related recombination remains an important loss pathway. Consequently, the optimized Sb ₂ Se ₃ /Al ₂ O ₃ /Zn _x Sn _1‐x O device achieves a champion power conversion efficiency of 9.28% with an enhanced open‐circuit voltage. These results demonstrate that ultrathin Al ₂ O ₃ interfacial modification provides an effective strategy for mitigating recombination‐related losses in high‐performance Cd‐free Sb ₂ Se ₃ solar cells.

Deep‐level defects in the bulk and near‐surface regions of Sb ₂ Se ₃ absorbers constitute important non‐radiative recombination pathways that limit photovoltaic performance. Here, we develop a near‐surface reconstruction strategy based on a mild solution‐processed sulfur treatment to regulate defect states and surface energetics of Sb ₂ Se ₃ . Controlled sulfurization of the Sb ₂ Se ₃ film facilitates the formation of S─Sb bonds in the near‐surface region, suppresses non‐radiative recombination, shifts the surface Fermi level upward, and enhances the built‐in electric field for charge separation. Meanwhile, limited sulfur diffusion into the shallow bulk substantially reduces deep‐trap densities and gives rise to slower photoexcited‐carrier relaxation/recombination dynamics. Furthermore, the spatially confined sulfur distribution largely preserves the bulk crystal structure, optical bandgap, and broad spectral response of the Sb ₂ Se ₃ absorber. Benefiting from the concurrent regulation of defect states and surface energetics, the optimized device achieves a power conversion efficiency of 10.89%, representing highly competitive performance among Sb ₂ Se ₃ solar cells.

In wide‐bandgap (WBG) perovskite solar cells (PSCs), residual lead iodide (PbI ₂ ) is a dual‐edged sword: while bulk retention stabilizes the α‐phase and suppresses defects, surface accumulation hinders charge transport and accelerates degradation under environmental stress. Herein, a solid‐phase reaction modification (SRM) strategy using L‐cysteine (L‐Cys) capping layer is reported to precisely regulate PbI ₂ distribution. Leveraging its highly polar functional groups, L‐Cys effectively eliminates surface PbI ₂ residues, mitigates interfacial defects, and releases residual lattice strain. These synergistic effects enable inverted PSCs (1.68 eV) fabricated through one‐step (spin coating) and hybrid two‐step (evaporation‐spin coating) fabrication methods to achieve a champion power conversion efficiency (PCE) of 23.27% and 19.63%. Furthermore, four‐terminal (4T) WBG PSC/copper indium gallium selenide (CIGS) tandem devices reach an impressive PCE of 28.14%. The SRM‐treated perovskite films exhibit exceptional robustness, showing no degradation under thermal aging (85°C, 24 h) or high humidity (85% RH, 72 h). Unencapsulated devices maintain 82.1% of their initial efficiency after 1000 h of ambient storage.

Vapor-phase deposition is crucial for scalable perovskite photovoltaics, yet precisely controlling organic-inorganic vapor-solid reactions to yield highly crystalline, phase-pure thin films remains a fundamental challenge. While close-spaced sublimation (CSS) provides an excellent platform for scalable manufacturing, its microstructural reliability is conventionally limited by decoupled nucleation and bulk phase conversion kinetics. Here, we elucidate the reaction kinetics governing CSS, identifying the total sublimation amount (TSA) as the defining parameter that dictates a diffusion-controlled, top-down phase evolution. We reveal a severe kinetic competition between the (100) and (111) crystallographic facets during growth: insufficient TSA leaves unreacted PbI2 at the buried interface, whereas excessive TSA drives disordered, (111)-dominant overgrowth. By rationally decoupling these kinetic stages via an in-situ atmosphere annealing (IAA) strategy, we selectively suppress the (111) facet and comprehensively eliminate basal PbI2, establishing a highly ordered (100) texture throughout the bulk. Consequently, the champion inverted (p-i-n) devices achieve efficiencies of 21.31% (0.04 cm²) and 18.35% (1.00 cm²). Demonstrating robust thermodynamic control, this approach delivers exceptional operational stability (retaining 90.4% efficiency over 1,000 h), and remarkable batch-to-batch reproducibility (1.68% relative standard deviation across 32 batches) providing a scalable, highly reproducible route for industrial-grade perovskite fabrication.

Antimony selenide (Sb ₂ Se ₃ ) has recently surpassed the benchmark of 10% power conversion efficiency, establishing itself as a highly promising photovoltaic absorber. However, its further development is largely limited by severe performance losses within the space charge depletion region near the heterojunction interface. Here, we introduce a solvent‐assisted annealing strategy utilizing dimethyl sulfoxide (DMSO) to effectively passivate the surface defects. The DMSO treatment simultaneously removes surface oxides and incorporates trace sulfur into the near‐surface region, thereby neutralizing surface states. Notably, the incorporated sulfur passivates deep‐level selenium vacancy defects V _Se2 and V _Se3 . Theoretical calculations reveal that DMSO chemisorbs onto Sb ₂ Se ₃ via strong Sb─S bonding, which weakens the native Sb─Se lattice and facilitates controlled surface etching. This passivation of interface regions significantly improves the heterojunction quality, yielding a champion power conversion efficiency of 10.48%, corresponding to a 17% relative improvement over the control device (8.99%). This work presents a simple yet effective route to defect mitigation in Sb ₂ Se ₃ photovoltaics, supporting their development toward practical application.

The hybrid two-step (evaporation-spin coating) fabrication method demonstrates substantial promise for achieving conformal perovskite growth on highly textured surfaces, such as industrially textured silicon heterojunction (SHJ) substrates with pyramidal features exceeding 1 μm. However, the presence of numerous process control parameters complicates the determination of optimal synthesis conditions. In this study, we employ a central composite design (CCD) based on response surface methodology (RSM) to systematically design and optimize the fabrication process. Analysis of variance (ANOVA) identifies substrate temperature during the evaporation step as a critical parameter governing device performance. We further explore the evaporation and perovskite formation kinetics to elucidate the impact of substrate temperature on film morphology and quality. Under optimized conditions, conformal perovskite growth on the textured surfaces is successfully realized. Wide band gap (1.68 eV) perovskite solar cells (PSCs) fabricated via this approach exhibited a power conversion efficiency (PCE) of 18.63% in the absence of additional treatments and 19.24% with phenylethyl ammonium iodide (PEAI) vapor passivation.

All‐perovskite tandem solar cells are regarded as the next generation of devices capable of enhancing the solar energy utilization rate. Unlike single‐junction perovskite solar cells (PSCs), the efficacy of tandem cells is contingent upon the performance of both the top and bottom cells. In this study, we employed a simultaneous co‐modification strategy to incorporate phenylethylammonium iodide (PEAI) at both the top and bottom interfaces of the perovskite film, aiming to boost the top cell's performance. Both experimental and theoretical findings indicate that PEAI not only elevates the perovskite film quality through chemical interactions but also mitigates nonradiative recombination within the device. Consequently, the efficiency of the wide‐bandgap (1.77 eV) PSCs based on nickel oxide (NiO_x) attained a level of 16.5%. Simultaneously, the all‐perovskite tandem solar cells achieved an efficiency of 26.81% and demonstrated superior stability.

Further improvement of the performance and stability of inverted perovskite solar cells (PSCs) is necessary for commercialization. Here, ferrocene derivative dibenzoylferrocene (DBzFe) is used as an additive to enhance the performance and stability of MA‐ and Br‐ free PSCs. The results show that the introduction of DBzFe not only passivates the defects in the film but also inhibits the ion migration in the film. The final device achieves a power conversion efficiency (PCE) of 23.53%, which is one of the highest efficiencies currently based on self‐assembled monolayers (SAMs). Moreover, it maintains more than 96.4% of the original efficiency when running continuously for 400 h at the maximum power point.

In recent years, tin halide perovskite solar cells (PKSCs) have emerged as a promising alternative to lead‐PKSCs. However, due to defects such as Sn⁴⁺ and iodide vacancies, their efficiency is lower than lead‐PKSCs. To address this issue, various strategies are proposed to improve the quality of perovskite, including copper iodide (CuI) doping. Unfortunately, the conventional solvent composition of DMF:DMSO = 4:1 has limited the solubility of CuI, resulting in inconsistent results and limited efficiency improvements. However, this research proposed a preprocessing method of CuI to decrease the defects and improve the perovskite layer's morphology. As a result, the efficiency of tin‐PKSCs with both P‐I‐N and hole transport layer (HTL) free structures is enhanced, increasing from 9.8% to 13.1% and 9.4% to 10.5%, respectively. Moreover, the doped tin‐PKSCs have exhibited better stability, retaining 75% of their initial power conversion efficiency (PCE) after being stored in a glovebox for 102 days.