Title: Hybrid organic-inorganic perovskite-based electronic devices

Abstract

The success of the organic-inorganic hybrid perovskite materials for the solar cell since 2009 has also extended to other applications such as memory devices, ultrafast switches and light - emitting diodes (LED), field-effect transistors, lasers, detectors, etc. Herein, we leverage the unwelcome ion-migration in perovskites to unlock new opportunities for resistive switching using layered Ruddlesdsen-Popper perovskites (RPP) and explicate the underlying mechanisms. The ON/OFF ratio of RPP-based devices is strongly dependent on the layers and peaks at n ̅ = 5; demonstrating the highest ON/OFF ratio and minimal operation voltage. Long data retention even in 60% relative humidity and stable write/erase capabilities exemplify their potential for memory applications. Impedance spectroscopy reveals a chemical reaction between migrating ions and the external contacts to modify the charge transfer barrier at the interface to control the resistive states. Our findings explore a new family of facile materials and the necessity of ionic population, migration and their reactivity with external contacts in devices for switching and memory applications. In parallel, we unravel the potential of the D2O as a solvent additive to enhance the PCE ~ 21% in triple cation based perovskite solar cells with stronger stability. Ultrafast optical spectroscopy confirms trap states passivation increased carrier recombination lifetimes and enhanced charge carrier diffusion lengths in our deuterated samples. Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy validates N-H2 group as the preferential isotope exchange site. Furthermore, first-principles density functional theory calculations reveal a decrease in PbI6 phonon frequencies in the deuterated perovskite lattice. This stabilizes the PbI6 structures and weakens the electron-phonon coupling, yielding higher electron mobility. Importantly, these findings prove that selective isotope exchange opens new opportunities for tuning perovskite optoelectronic properties.