Highly controllable synthesis of MAPbI3 perovskite nanocrystals with long carrier lifetimes and narrow band gap for application in photodetectors

Abstract Low-dimensional organic-inorganic hybrid perovskite materials have attracted much attention in photoelectric devices due to their exotic performance in optoelectronics compared with their bulk and thin-film counterparts. In this article, using a simple ligand-assisted deposition method, we successfully synthesized uniform methylammonium lead iodide (MAPbI3) perovskite nanorods, nanotriangles and nanocubes, and investigated their photoelectric properties after fabricated into photodetectors (PDs) on SiO2/Si substrates. It is found that the synthesized MAPbI3 nanorods not only have extremely small optical band gap（minimum of~1.36 eV）, but also have long photoluminescence（PL） lifetime (longest of~7.81 μs) and high absolute PL quantum yields (maximum of ~ 45%), and the PL lifetime is more than about one order of magnitude higher than that the reported previously. The PDs based on MAPbI3 nanorods presented a wide spectral response "window" from 350 to at least 950 nm, and exhibited a photoresponsivity of 12.2 mA/W, a detectivity of 2.67 ✕ 1011 Jones, the on/off ratio of more than 800, the rise/decay time constants of 18/25 ms, under the excitation at 405 nm. Further analysis suggests that the dramatically improved photo-electric conversion properties of the nanorods PDs could be closely related with their morphology dependent properties, including bandgap, PL lifetime, trap density (ntrap) and carrier concentration. These results provide a simple and effective method for preparing different morphology low-dimensional MAPbI3, and discuss the mechanism of morphology-dependent photoelectric performance of PDs, which is of great significance for potential applications in the field of photoelectronic devices.