Sep 7, 2017 - ORIGINAL PAPER www.crt-journal.org. Asymmetrical Photodetection Response of. Methylammonium Lead Bromide Perovskite Single Crystal.
ORIGINAL PAPER www.crt-journal.org
Asymmetrical Photodetection Response of Methylammonium Lead Bromide Perovskite Single Crystal Xin Wang, Yin Huang, Wei Lei,* Qing Li, Xiaobing Zhang, Qasim Khan, and Baoping Wang The ideal perovskite methylammonium lead bromide (MAPbBr3 ), in which methylammonium(MA) and lead(Pb) are cations and bromine represents an anion, has a simple cubic crystal structure that consists of a corner-shared PbBr6 octahedral network with a Pb-Br-Pb bond angle of 180° and MA ions located in the interstices.[8] However, it has been found that these perovskites may adopt structures with reduced symmetry because of the low-temperature fabrication processes.[9,10] Previous investigations showed that the carrier transport properties in these perovskites were influenced by defects,[11–13] and by their grain boundaries and grain sizes.[14,15] Therefore, the photodetection responses of MAPbBr3 PSCs may be asymmetrical because of their low-symmetry crystal structures. This asymmetrical property is quite important in the design of photodetectors based on PSCs, and the electrical properties and photodetection responses along the different axis directions of MAPbBr3 PSCs were investigated intensively in this work. High-quality MAPbBr3 PSCs were synthesized by inverse temperature crystallization (ITC) or anti-solvent vapor-assisted crystallization (AVC) process.[12,13] However, the crystallization rates in these methods were rapid, resulted into several pieces of the MAPbBr3 PSCs growth simultaneously.[16] Consequently, the sizes of the available MAPbBr3 PSCs were usually limited. Therefore, to develop a perovskite photodetector with a suitably large detection area, the variable temperature crystallization (VTC) method has been proposed for synthesis of large-sized MAPbBr3 PSCs in demonstration. In the VTC method, the nucleation and rapid growth processes of small single crystal seeds were separated because the solubility of the MAPbBr3 perovskite changed slightly in low-temperature reaction processes (
