An efficient and stable tin-based perovskite solar cell passivated by aminoguanidine hydrochloride†
It is challenging to fabricate a simultaneously high-performance and stable Sn-based perovskite device owing to the inferiority of the Sn-based perovskite film and the rapid oxidation of Sn2+. Herein, a simple approach was employed and involved introducing an additive of aminoguanidine hydrochloride (NH2GACl) into a perovskite precursor solution to prepare efficient Sn-based perovskite solar cells. A higher film quality was obtained, due to the formation of strong hydrogen bonding between halide ions in the perovskite and NH2GACl, which helped to passivate the defects and lessen the rate of Sn2+ oxidation. Also, the addition of NH2GACl was indicated to effectively adjust the energy level alignment between Sn-based perovskite and the adjacent layer, with this adjustment facilitating the charge transport. The perovskite device modified with NH2GACl achieved a power conversion efficiency of up to 7.3%, and retained 90% of its initial efficiency after 30 days in a nitrogen glovebox without being encapsulated.