In Situ Microscopic Observation of Humidity-Induced Degradation in All-Inorganic Perovskite Films

Abstract

All-inorganic perovskites with thermal stability suffer from a major barrier toward photovoltaic applications due to the sensitivity of environmental factors. In this paper, the degradation mechanisms of all-inorganic perovskite CsPbI2Br under a humid environment are systematically examined from a microscopic viewpoint. It is found that the level of relative humidity (RH) is important for the degradation process. In situ scanning probe microscopy measurements disclose that CsPbI2Br degradation initiates at the grain boundaries and extends toward the grain interiors. The corresponding surface potential, local conductivity, and photosensitivity of the perovskite exposed to the 50% RH condition are systematically investigated. The correlations between the degradation process of inorganic perovskites and the evolved photovoltaic performance of solar cells are well addressed. Understanding the degradation pathway will be beneficial to designing more stable perovskites and robust photovoltaic devices.

Pulsed Force Kelvin Probe Force Microscopy through Integration of Lock-In Detection

“…Revealing the Electronic State Degradation of the [Cs 0.05 (FA 0.93 MA 0.07 ) 0.95 PbI 3 ] Perovskite. Mixed halide perovskites (MHPs) can undergo photoinduced, 34 moistureinduced, 35 thermal, 36 halide exchange, 37 and ion migration degradation under different circumstances, 38 which result in the instability of their photovoltaic properties and decrease their efficiency. 34 These types of degradations and their effects on the properties of MHP have been studied before by comparing the effect of degradation on the MHP properties at the macroscopic level, i.e., through the measurable performance reduction of the devices.…”

Advancements and Prospects in Perovskite Solar Cells: From Hybrid to All-Inorganic Materials

“…Similarly, Yao W. et al obtained comparable results for CsPbI 2 Br perovskites, where for RH values above 50%,e α-CsPbI 2 Br (the black phase) decomposed into δ-CsPbI 2 Br (the yellow phase) and later into PbI 2 . These processes are initiated at the grain boundaries of thin films, with generated ions migrating into the grain interiors due to a potential difference [ 168 ].…”

Pulsed Force Kelvin Probe Force Microscopy─A New Type of Kelvin Probe Force Microscopy under Ambient Conditions

“… 43 The photovoltaic properties and efficiency of MHPs, however, are highly dependent on their stability. 44 These perovskites can degrade in the presence of light, 44 humidity, 45 at high temperatures, 46 and also endure halide exchange 47 or ion migration 48 which results in a reduction in the efficiency and instability of these materials. 44 However, detecting the initial phase of these degradations could be highly beneficial to achieve preventive and remedial measures.…”