Antisolvent‐Induced Fastly Grown All‐Inorganic Perovskite CsPbCl\n 3\n Microcrystal Films for High‐Sensitive UV Photodetectors

Abstract

DOI: 10.1002/admi.202001812 temperature stability, and transparent to visible radiation.[2] Typically, all-inorganic perovskite CsPbCl3 with a wide bandgap (Eg > 2.9 eV) is intrinsically sensitive to UV radiation, and can be potentially developed and utilized for high-performance UV-PDs.[3] Recently, compared with the widely studied and extensively used organic–inorganic hybrid halide perovskites in optoelectronic and photovoltaic devices, all-inorganic halide perovskite CsPbCl3 not only has excellent photoelectric properties, but also naturally possesses the better chemical stability and bandgap tunability due to the replacement of organic methyl ammonium with inorganic Cs cations.[4] The previously reported works on perovskites mainly focused on the preparation of various nanostructures, including quantum dots, nanocrystals, nanowires, and nanosheets.[5] With a comparison to nanostructures, micrometeror millimeter-sized perovskite crystals have the fewer defects and grain boundaries, and then exhibit the better intrinsic properties such as the lower trap density and the longer photogenerated carrier lifetime, resulting in the better performance of as-prepared devices.[6] Although there have been many reports about CsPbBr3 microcrystals and single crystals, CsPbCl3 large crystals were still mainly obtained by using the traditional high-cost Bridgman method, with the stringent requirements of high temperature (near 600 °C), high vacuum (10−2 Pa), and high-purity starting reagents.[7] In addition, as the bulk single crystals have trouble forming a film and are difficult to indirectly integrate with easily applied planar substrate, the additional crystal growth processes or cutting-down processes have to be employed to reduce the thickness.[8] But these processes would easily lead the secondary damage of the crystal, badly restricting the performance of devices and greatly adding its manufacturing cost. Recently, the CsPbCl3 crystals with a size of tens of micrometers were successfully prepared at low temperature (50 °C) and atmospheric environment.[6a] In this method, antisolvent vapor was employed to slowly reduce the solubility of the perovskite precursor for maintaining slightly supersaturated precursor solution, slowly promoting the crystallization and growth of CsPbCl3 crystals. Although there is a great improvement in the temperature and environment of crystal growth, this method CsPbCl3-based inorganic perovskite ultraviolet photodetectors (UV-PDs) have a great promise for the wide application prospects due to the desirably UVmatched energy band and the excellent intrinsic optoelectronic properties. However, the traditional high-temperature Bridgman method (near 600 °C) and complexly time-consuming vapor preparation (several days) of highquality CsPbCl3 crystals have badly restricted its commercial applications to date. Herein, an antisolvent-induced crystallization kinetics (ACK) strategy is demonstrated for the quick lower-temperature fabrication (50 °C, tens of minutes) of excellent continuous highly crystalline CsPbCl3 microcrystal films (MCFs) with low trap density (1.42 × 1012 cm−3). Further, the as-developed CsPbCl3 MCF-based UV-PDs present a high detectivity of 5.6 × 1012 Jones, a superior responsivity of 2.11 A W−1, and robust stability. Evidently, this work provides a rapid and simple method to prepare high-quality perovskite MCFs, greatly promoting the commercial development of perovskite-based photodetectors.