Dimethylamine Hydrochloride Passivated Perovskite Surface Towards Enhanced Solar Cell Performance

Solution processed polycrystalline perovskite films surface frequently suffers from defects and charge traps especially in the grain boundaries (GB) deteriorating the overall device performance. In this work, for the first time we report Dimethylamine hydrochloride (DMH) as an effective passivating agent for perovskite surface in the inverted structure solar cell. When DMH (C₂H₇NHCl) is employed on MAPbI₃ surface, it reduces defects and filled trap states in the perovskite GB. As a result, passivated MAPbI₃ films possess smaller non-radiative recombination as supported by photoluminescence spectra. Besides, DMH passivated perovskite films exhibit higher surface current and less RMS roughness which are beneficial for good interfacial contact and efficient charge transportation. Consequently, photogenerated charge transport time is decreased after the passivation. Basically, DMH performs Pb-N coordination bonding with Pb²⁺ and deactivates the malefic under-coordinated Pb²⁺ on perovskite surface or GB which helps to improve the device performance. Eventually, the power conversion efficiency (η) jumps from 15.17% to 17.50% through the simultaneous improvement of short circuit current density (J_sc) and open circuit voltage (V_oc) in the DMH passivated MAPbI₃ perovskite solar cells.