Ion Migration in the All-Inorganic Perovskite CsPbBr₃ and Its Impacts on Photodetection

Abstract

Ion migration has been widely investigated in the lead halide perovskites, which severely deteriorates the performance of solar cells. However, the impacts of ion migration on photodetection have been rarely studied so far. In the current work, ion migration in the all-inorganic perovskite CsPbBr3 and its impacts on photodetection have been investigated in detail. Electrical property studies showed that ion migration has occurred under an external electric field poling, which led to the formation of a pn-junction within the CsPbBr3 single crystals. Density function theory calculations have shown that vacancy-assisted Br-ion migration dominated the ion transportation processes. Accordingly, the Au/CsPbBr3/Au metal–semiconductor–metal structured photodetectors showed a decreased performance in terms of a decreased on–off ratio and decreased detectivity through a long-term operation under a bias voltage, although the photoresponsivity slightly increased simultaneously. The results provided in this work verify the negative effects of ion migration in the all-inorganic perovskite CsPbBr3, which may account for the instability of CsPbBr3-based optoelectronic devices reported in the literature.

Field-Induced Transport Anisotropy in Single-Crystalline All-Inorganic Lead-Halide Perovskite Nanowires

“…Due to the top-contact device structure, the gold electrodes are thinner at the side of the NW, so that the scattered light from the laser spot may be collected by the Au-NW Schottky junction. As Br anions have been identified as the mobile ions in CsPbBr 3 , 38 the positively charged ions are likely Br vacancies, which accumulate near the cathode. The concentration of accumulated vacancies can alter the local Fermi energy level, 26 resulting in significant band bending and strong internal electric field (Figure 2d).…”

Revealing energy storage mechanism of CsPbBr3 perovskite for ultra-stable symmetric supercapacitors

“…Specifically, it is known that the chemical bonding strength between the Cs + cation in the perovskite crystal structure with the [PbBr x ]the framework is weak, and the energy barrier for migration of Cs + in the perovskite crystal structure is 0.3-0.7 eV [42][43][44] . Experimental evidence has shown that Cs + can drift away from the perovskite crystal structure under certain electrical fields which are high enough to overcome the energy barrier for Cs + migration.…”

A Polymer Strategy toward High‐Performance Multifunctional Perovskite Optoelectronics: From Polymer Matrix to Device Applications

“…Cation doping, small molecule or polymer addition, and low dimensional perovskites have been reported to strengthen the crystal structure, improve the crystalline quality, and enhance the moisture and thermal resistance, thus suppressing ion migration. [139][140][141][142] Ma et al presented that both polymers of poly [4,8-…”

“…Cation doping, small molecule or polymer addition, and low dimensional perovskites have been reported to strengthen the crystal structure, improve the crystalline quality, and enhance the moisture and thermal resistance, thus suppressing ion migration. [ 139–142 ] Ma et al. presented that both polymers of poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] (PCE10) with a large dipole moment of 3.7D and PS with a small dipole moment of 0.6D restricted ion movement and improved the device stability ( Figure a).…”