Small molecule of aminoacetonitrile hydrochloride prompting large improvement in the performance of perovskite solar cells

Perovskite solar cells (PSCs) continuously update their best research efficiency records, currently has exceeded 26 %. However, the industrialization of PSCs still faces the issues of stability and performance improvement, and interface defects are notorious negative factors. Herein, a small molecule aminoacetonitrile hydrochloride (AAN) as multi-functional additive is introduced into the interface of tin oxide (SnO 2 )/perovskite. The cyano group (C N) on AAN can coordinate with Pb 2+ on perovskite; Cl − can occupy halide vacancy in perovskite and oxygen vacancy on SnO 2 , and NH 3 + can form hydrogen bonding with iodide ions in perovskite. It is verified that crystal growth quality is improved, trap-state density is reduced, energetic alignment is adjusted, charge transfer is ameliorated, and carrier recombination is alleviated. Therefore, the AAN-modified PSC achieves a maximum power conversion efficiency of 24.52 % with a high open-circuit voltage of 1.18 V and satisfactory stability, compared to the unmodified device efficiency of 21.24 %, demonstrating a significant impact of the multi-functional small molecule of AAN in highly efficient and stable PSCs. • A small molecule additive AAN is introduced into the interface of SnO 2 /perovskite. • −C N, Cl − , and NH 3 + on AAN effectively passivate the defect in the buried interfaces. • AAN also improves crystal quality, turns energy level match and quickens charge transport. • AAN-modified PSC achieves a champion efficiency of 24.52 % with a V OC of 1.18 V.