Inverse Growth of Large-Grain-Size and Stable Inorganic Perovskite Micronanowire Photodetectors.

Control of forward and inverse reactions between perovskites and precursor materials is key to attaining high-quality perovskite materials. Many techniques focus on synthesizing nanostructured CsPbX materials (e.g., nanowires) via a forward reaction (CsX + PbX → CsPbX). However, low solubility of inorganic perovskites and complex phase transition make it difficult to realize the precise control of composition and length of nanowires using the conventional forward approach. Herein, we report the self-assembly inverse growth of CsPbBr micronanowires (MWs) (CsPbBr → CsPbBr + PbBr↑) by controlling phase transition from CsPbBr to CsPbBr. The two-dimensional (2D) structure of CsPbBr serves as nucleation sites to induce initial CsPbBr MW growth. Also, phase transition allows crystal rearrangement and slows down crystal growth, which facilitates the MW growth of CsPbBr crystals along the 2D planes of CsPbBr. A CsPbBr MW photodetector constructed based on the inverse growth shows a high responsivity of 6.44 A W and detectivity of ∼10 Jones. Large grain size, high crystallinity, and large thickness can effectively alleviate decomposition/degradation of perovskites, which leads to storage stability for over 60 days in humid environment (relative humidity = 45%) and operational stability for over 3000 min under illumination (wavelength = 400 nm, light intensity = 20.06 mW cm).