The emerging methylammonium lead halide perovskite are the ideal materials of specific interest for diverse optoelectronic applications, for instance, photovoltaic, light emitting diode (LED), laser and photodetector, etc. Especially in the field of photovoltaics, the photo-to-electron conversion efficiency of perovskite solar cells (PSCs) has rapidly risen from 3.8% to 22.1% within a few years. According to the literature, the nature of polycrystalline perovskite films as the main absorbing layer of PSCs intrinsically impedes further improvement of cell performance due to the fact that tremendous amount of grain boundaries and defects existing within polycrystalline perovskite films serves as recombination center and thus hinders efficient diffusion of charge carriers, which confines diffusion length of charge carriers within only few micrometers. Therefore, breakthrough improvement of its efficiency will rely decisively on the finest control or minimize grain boundaries and trap densities of perovskite materials, which eventually could be single crystalline perovskite materials. Among various morphologies of perovskite single crystals, ultrathin large scale perovskite platelets, which have the shape with much-extended dimension up to centimeters scale along x, y-direction but confined dimension down to less than 1 µm in z-direction, possess the practical potential for fabricating high-performance optoelectronic devices. This proposal will tackle with the synthetic challenges of single crystalline perovskite materials with controllable dimension and its integration with optoelectronic devices such as solar cell, LED and laser for potential breakthrough of device performance. This envisioned combined approach, as far as we know, is herein explored for the first time.
In this project, we are planned firstly tackle with synthetic obstacles obtaining those single crystals with tailored dimension, especially ultrathin large scale perovskite platelets, by either chemical solution process which takes advantage of template formed by specific metal oxide frame or functional surfactants, or spatial atmospheric atomic layer deposition process which requires an epitaxial growth by feeding specific precursor vapor of perovskite raw materials. With those materials in hand, various optoelectronic devices, especially solar cell as the initial attempt, will be constructed based on those synthesized large scale single-crystalline perovskite materials for a potential breakthrough of device performance, and characterized with advanced optical and electronic tools and techniques to correlate device performance with the nature of single crystalline perovskite materials.
