The formation of point defects in the crystal lattice of organic–inorganic hybrid perovskites is detrimental to the long-term stability of the perovskite-based solar cell. The observed hysteresis in organolead halide perovskite solar cell during the photocurrent measurement is believed to be the consequence of such defect sites. In the present work, we are reporting the formation of reversible and/or irreversible lattice defects in methylammonium lead iodide perovskite depending on the magnitude of bias voltage studied by electrical measurements and positron annihilation spectroscopy (PAS). Current vs voltage (I–V) measurements support the formation of p/n junction at the metal/semiconductor interfaces, suggesting the defects-driven ion migration under the applied bias. In-situ PAS has elucidated the nature of vacancy sites formed due to the application of bias voltage. In the lower biased voltage (<1 V), the formation of lattice defects is reversible, while beyond a threshold voltage of 1.2 V, the defects become permanent as observed by the PAS.

有机-无机杂化钙钛矿晶格中点缺陷的形成不利于钙钛矿基太阳能电池的长期稳定性。在光电流测量期间观察到的有机铅卤化物钙钛矿太阳能电池的滞后被认为是这种缺陷位点的结果。在目前的工作中，我们报告了甲基铵碘化铅钙钛矿中可逆和/或不可逆晶格缺陷的形成，这取决于电测量和正电子湮没光谱 (PAS) 研究的偏置电压的大小。电流 vs 电压 ( I – V ) 测量支持在金属/半导体界面形成 p/n 结，表明在施加的偏压下缺陷驱动的离子迁移。原位PAS 阐明了由于施加偏置电压而形成的空位的性质。在较低的偏置电压 (<1 V) 下，晶格缺陷的形成是可逆的，而超过 1.2 V 的阈值电压，如 PAS 所观察到的那样，缺陷变得永久性。