The failure of perovskite solar cells (PSCs) under ultraviolet (UV) irradiation is a serious barrier of commercial utilization. Here, a two-stage degradation process of TiO₂-based PSCs is discovered under continuous UV irradiation in an inert atmosphere. In the first decay stage, oxygen vacancy-Ti³⁺ (Ti³⁺-V_O) transform into active Ti⁴⁺-V_O trap states under UV excitation and cause photocarrier loss. Furthermore, Ti⁴⁺-V_O states can convert back into Ti³⁺-V_O states through oxidizing I⁻, which result in the accumulation of I₃⁻. Sequentially, the rapid decomposition of perovskite accelerated by increasing I₃⁻ replaces the photocarrier loss as the dominant mechanism leading to the second decay stage. Then, a universal method is proposed to improve the UV stability by blocking the transformation of Ti³⁺-V_O states, which can be realized by polyethyleneimine ethoxylated (PEIE) modified layer. The optimized devices remain ∼75% of its initial efficiency (20.51%) under UV irradiation at 72 days, whereas the normal devices fail completely.

钙钛矿太阳能电池（PSCs）在紫外线（UV）照射下的失效是商业应用的严重障碍。在此，在惰性气氛中连续紫外线照射下，发现了基于TiO ₂的PSCs的两步降解过程。在第一个衰变阶段，氧空位-Ti ³⁺（Ti ³⁺ -V _O）在紫外线激发下转变为活性Ti ⁴⁺ -V _O陷阱态，并导致光载流子损失。此外，TI ⁴⁺ -V _Ø状态可以转换回钛³⁺ -V _Ø国通过氧化我^- ，这导致我的积累₃ ^-。随后，钙钛矿的迅速分解，加速通过增加我₃ ^-取代了光生载损失的主要机制导致第二衰退阶段。然后，通用方法，提出了通过阻断Ti中的变换，以改善UV稳定性³⁺ -V _ø状态，其可以通过聚乙烯亚胺来实现乙氧基化（PEIE）改性层。经过优化的设备在72天的紫外线照射下仍可保持约75％的初始效率（20.51％），而普通设备则完全失效。