Kung Po-Kai, Lin Kuang-I, Wu Chun-Sheng, Li Ming-Hsien, Chan Chia-Ru, Rajendran Raja, Lin Chen-Fu, Chen Peter
Department of Photonics, National Cheng Kung University, Tainan 701, Taiwan.
Core Facility Center (CFC), National Cheng Kung University, Tainan 701, Taiwan.
J Phys Chem Lett. 2022 Aug 4;13(30):6944-6955. doi: 10.1021/acs.jpclett.2c01515. Epub 2022 Jul 25.
In this work, we present the ion migration of CsPbIBr under illumination and impede it by incorporating the large cations of guanidinium (GA). A series of "probe-set-probe" operations are applied to assess the photoluminescence (PL) behavior spectrally and spatially, which is correlated to the ion migration-induced phase separation, of CsPbIBr and GACsPbIBr perovskites. The local lattice distortion introduced by GA could reduce the strain gradient in GACsPbIBr to inhibit the ion migration, leading to a stable PL spectrum and enhanced device stability under light stimulation. A solar cell with an optimized stoichiometric composition of GACsPbIBr delivers comparable photovoltaic performance and improved stability compared to those of CsPbIBr-based perovskite solar cells, retaining 80% of its initial power conversion efficiency after being continuously bathed in light for 8 h under ambient conditions without encapsulation, while the CsPbIBr counterpart shows an efficiency that is <30% of its initial value under the same test condition.
