Hydrazinium cation mixed FAPbI3-based perovskite with 1D/3D hybrid dimension structure for efficient and stable solar cells

Abstract FAPbI3 has been greatly developed in Perovskite solar cells (PSCs) profiting from their narrow bandgap, high panchromatic absorption and long carrier diffusion length. Unfortunately, the phase instability of FAPbI3-based perovskite restricts its further development in PSCs. Here, hydrazinium cation (HA+: NH2NH3+) is incorporated into FAPbI3-based perovskite to obtain novel 1D/3D hybrid dimension structure with stable α-FAPbI3 for the first time. The strong hydrogen bonding of HA+ increases the crystallinity and grain size of perovskite. Furthermore, SEM and TEM reveal that the new HA based 1D-phase (1D-HA-phase) exists like “rivet” passivating among the grain boundary of 3D perovskite, forming 1D/3D hybrid dimension structure contributing to the stability of FAPbI3-based perovskite. Confocal fluorescence microscopy, time-resolved photoluminescence spectroscopy and Kelvin probe force microscope measurements reveal that the trap state can be effectively restrained and the non-radiative recombination is largely suppressed in HA+ mixed FAPbI3-based perovskite film with 1D-HA-phase. Finally, stable α-FAPbI3-based perovskite and its film with high crystallinity, smooth surface morphology, excellent photovoltaic performance and few defects are obtained. PSC using (FAMACs)0.85HA0.15 perovskite achieves a power conversion efficiency of 21.20% which can retain 90% at room temperature in ambient environment for 2520 h.