Trap-assisted charge recombination and interfacial charge recombination have limited further improvements in the efficiency and stability of perovskite solar cells. We construct a novel two-dimensional (2D) black phosphorus nanosheet (BP NS)-modified perovskite model that utilizes an upgraded additive post-processing technique to introduce 2D BP NSs, comprising multiple functional groups and carrying a high charge mobility and high work function, into the absorber during Ostwald ripening. 2D BP NSs, while passivating grain boundaries and surface defects, successfully induced the in-situ formation of an intriguing n/p homojunction structure between the underlying bulk and the top in a monolithic perovskite film, i.e., a graded n/p-PVK-BP absorber. This resulted in the synergistic advantages of expanding the built-in electric field to facilitate the oriented transfer of photogenerated carriers, optimizing the energy level alignment, and minimizing the hole injection barrier at the perovskite/hole transporting layer interface, thereby accelerating the selective extraction/collection of interfacial charges and synchronously reducing nonradiative and interfacial charge recombination losses. The 2D BP NSs anchored at the grain boundaries and surface of p-type perovskite form a “fast path” for hole migration, achieving carrier transport balance at the top and bottom interfaces. The optimized n/p-PVK-BP device achieved an efficiency of 23.22 %, with negligible hysteresis. Owing to the synergistic effects of the various advantages of the graded n/p-PVK-BP homojunction absorber, the unencapsulated device exhibited good long-term storage and operational stability, providing potential for commercial conversion of perovskite-based optoelectronics. This work provides a simple homojunction structure design and performance optimization strategy for the simultaneous reduction of trap-assisted charge recombination and interfacial charge recombination losses and provides new insights for the development of more efficient and stable perovskite photovoltaic applications.

中文翻译：

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通过使用黑磷纳米片自发重建单片钙钛矿薄膜中的 n/p 同质结来减少光伏电池中的电荷复合损失


陷阱辅助电荷复合和界面电荷复合限制了钙钛矿太阳能电池效率和稳定性的进一步提高。我们构建了一种新型二维（2D）黑磷纳米片（BP NS）改性钙钛矿模型，该模型利用升级的添加剂后处理技术引入2D BP NS，包含多个官能团并具有高电荷迁移率和高功函数，在奥斯特瓦尔德熟化过程中进入吸收器。 2D BP NS 在钝化晶界和表面缺陷的同时，成功诱导了在单片钙钛矿薄膜的底层块体和顶部之间原位形成有趣的 n/p 同质结结构，即梯度 n/p-PVK- BP吸收器。这产生了扩大内置电场以促进光生载流子的定向转移、优化能级排列以及最小化钙钛矿/空穴传输层界面处的空穴注入势垒的协同优势，从而加速了选择性提取/收集界面电荷并同步减少非辐射和界面电荷复合损失。锚定在p型钙钛矿晶界和表面的2D BP NS形成空穴迁移的“快速路径”，实现顶部和底部界面的载流子传输平衡。优化后的 n/p-PVK-BP 器件效率达到 23.22%，滞后现象可以忽略不计。由于梯度n/p-PVK-BP同质结吸收器的各种优点的协同效应，未封装的器件表现出良好的长期存储和操作稳定性，为钙钛矿基光电子学的商业转化提供了潜力。 这项工作提供了一种简单的同质结结构设计和性能优化策略，用于同时减少陷阱辅助电荷复合和界面电荷复合损失，并为开发更高效、稳定的钙钛矿光伏应用提供了新的见解。