Longxian Zhang,Zhineng Zhou,Lang Wu,Qiaogang Song,Yu Zhuang,Chi Yang,Xintong Zhao,Juchuan Chai,Shurong Wang
The two-step method facilitates perovskite crystallization by pre-generating PbI 2 crystal nuclei and exhibits superior repeatability. Nevertheless, the two-step fabrication process results in a perovskite layer with many grain boundaries and interfacial defects, which act as non-radiative recombination sites, significantly limiting the V OC . At the same time, the quality of the resulting film strongly relies on how effectively organic salts diffuse within the PbI₂ layer. Herein, through a pre-deposition strategy, A pre-deposited NH 4 Br layer at the SnO 2 /perovskite interface effectively modulated the growth behavior of perovskite crystals. This led to the formation of a vertically grown perovskite film, featuring an average grain size of 1.37 μm. The pre-deposited NH 4 Br not only effectively suppressed interface recombination by reducing defect densities and enhanced carrier extraction, but also effectively improved perovskite film crystallinity and reduced PbI 2 content. Furthermore, the pre-deposition strategy extended the average carrier lifetime to 2.3 μs. Finally, perovskite devices based on pre-deposited NH 4 Br layer achieved a power conversion efficiency of 25.46 % and exhibited negligible hysteresis and good stability. In a word, the early incorporation of NH 4 Br at the SnO 2 /perovskite interface provides an effective approach to improving interfacial contact and reducing recombination, thereby enhancing device efficiency and long-term operational stability.
Kesterite Cu 2 ZnSn(S, Se) 4 is considered one of the most competitive photovoltaic materials due to its earth-abundant and nontoxic constituent elements, environmental friendliness, and high stability. However, the preparation of high-quality Kesterite absorbers for photovoltaics is still challenging for the uncontrollability and complexity of selenization reactions between metal element precursors and selenium. In this study, we propose a solid-liquid/solid-gas (solid precursor and liquid/vapor Se) synergistic reaction strategy to precisely control the selenization process. By pre-depositing excess liquid selenium, we provide the high chemical potential of selenium to facilitate the direct and rapid formation of the Kesterite phase. The further optimization of selenium condensation and subsequent volatilization enables the efficient removal of organic compounds and thus improves charge transport in the absorber film. As a result, we achieve high-performance Kesterite solar cells with total-area efficiency of 13.6% (certified at 13.44%) and 1.09 cm 2 -area efficiency of 12.0% (certified at 12.1%).
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