Nucleation-controlled growth of superior long oriented CsPbBr3 microrod single crystals for high detectivity photodetectors

Abstract

There has been great interest in the use of cesium lead bromide (CsPbBr₃), which is one of the most important members of the all-inorganic perovskite family, due to its superior optoelectronic performance and higher stability. Recently, it has been demonstrated that it is advantageous to use CsPbBr₃ microrods and nanowires in photodetectors because of their higher crystallinity, low amount of defects, and easy control of carrier transport along a specific direction as compared to their counterparts of single crystals and thin films. However, there is a shortage of adequate investigations that describe how to control the growth of CsPbBr₃ microrods and nanowires so that they retain the optoelectronic performance of single CsPbBr₃ microrods. Therefore, we are reporting how to control the growth of orientated dispersive super-long CsPbBr₃ microrod single crystals (CsPbBr₃ MSCs) via a simple anti-solvent method. The crucial factor in controlling the growth of dispersive super-long CsPbBr₃ MSCs is the regulation of the rapid nucleation rate and slowing of the growth rate via controlling the diffusion velocity of anti-solvent methanol. We also reveal the growth mechanism of CsPbBr₃ MSCs as layer-by-layer growth that originates from the 2D nucleus. The CsPbBr₃ MSCs are revealed grew in the direction of [010], with the (101) facet exposed. Moreover, photodetectors based on one CsPbBr₃ MSC were fabricated, and the detectivity (D) and the on/off ratio were as high as 3.67 × 10¹² Jones and 988, respectively, suggesting a very strong optoelectronic response as photodetectors. The mechanism that the Cs ions and Cs vacancies use to move to negative and positive electrodes along the channels constructed by [PbBr₆]⁴⁻ in the [010] direction of the CsPbBr₃ MSC (101) facet was revealed, after activation by the applied electrical field, which is beneficial to enhance the optoelectronic response but does not reduce the device stability.