Perovskite solar cells (PSCs) suffer from significant nonradiative recombination, limiting their power conversion efficiencies. Here, for the first time, we directly observe a complete transformation of perovskite MAPbI₃ surface region energetics from p- to n-type during defect passivation caused by natural additive capsaicin, attributed to the spontaneous formation of a p-n homojunction in perovskite active layer. We demonstrate that the p-n homojunction locates at ∼100 nm below perovskite surface. The energetics transformation and defect passivation promote charge transport in bulk perovskite layer and at perovskite/PCBM interface, suppressing both defect-assisted recombination and interface carrier recombination. As a result, an efficiency of 21.88% and a fill factor of 83.81% with excellent device stability are achieved, both values are the highest records for polycrystalline MAPbI₃ based p-i-n PSCs reported to date. The proposed new concept of synergetic defect passivation and energetic modification via additive provides a huge potential for further improvement of PSC performance.

钙钛矿太阳能电池（PSC）遭受大量的非辐射重组，从而限制了其功率转换效率。在这里，我们首次直接观察到钙钛矿MAPbI ₃表面能从p-完全转变为n-由天然添加剂辣椒素引起的缺陷钝化过程中的这种类型，归因于钙钛矿活性层中pn同质结的自发形成。我们证明了pn同质结位于钙钛矿表面以下约100 nm处。高能转变和缺陷钝化促进了整体钙钛矿层和钙钛矿/ PCBM界面处的电荷传输，从而抑制了缺陷辅助重组和界面载流子重组。结果，获得了21.88％的效率和83.81％的填充因子，具有出色的器件稳定性，这两个值都是多晶MAPbI ₃的最高记录迄今已报告的基于引脚的PSC。提出的协同缺陷钝化和通过添加剂进行能量修饰的新概念为进一步提高PSC性能提供了巨大的潜力。