Title | Investigation of interfaces in perovskite-based optoelectronic devices
Date | November 6, 2023
Abstract | Metal halide perovskites (MHP) form a novel class of materials that recently found application in solar cells (SC). Being in an early stage of study and understanding, MHP-based SCs still suffer from low operational lifetime, exacerbated by using chemically reactive selective carrier transport layers (SCTLs), such as TiO2 and NiO. During this PhD, the optoelectronic properties of MHPs deposited on SCTLs have been studied by combining advanced characterization techniques, such as X-ray photoemission spectroscopy (XPS), and surface photovoltage (SPV), with 2D drift-diffusion simulations. Our analysis of XPS data acquired in near thermal equilibrium conditions suggests that the MHP layer employed in SCs is very lowly doped (Ndop<1011 cm-3), indicating high electronic quality. Moreover, charge photogeneration and redistribution in MHP/TiO2 stacks, probed by SPV, indicate the presence of deep traps inside TiO2 that store a large number of electrons under illumination. Furthermore, a signature of shallow traps in the MHP layer was found. These traps temporarily capture photogenerated electrons, slowing down charge extraction, and causing carrier loss.
