Bidirectional passivation of the SnO2/perovskite interface in perovskite solar cells through organic salt 3-Hydroxytyramine hydrochloride

SnO2 offers compelling advantages as an excellent electron transport layer material in perovskite solar cells. However, the defects caused by oxygen vacancies are unfavorable to the interface contact and would hinder the device performance. A simple and effective interface passivation strategy using 3-Hydroxytyramine hydrochloride (3-Hh) is developed, which realizes the bidirectional passivation of electron transport layer and perovskite. The passivation mechanism of 3-Hh is investigated. Further, the morphology of the subsequent deposited perovskite film is improved. The modified perovskite film exhibits increased grain size with better uniformity, reduced grain boundaries, lowered defect density. A relatively higher power conversion efficiency of 22.63% is achieved for the perovskite solar cells based on the bidirectional passivation of SnO2/perovskite interface. Meanwhile, the modified devices can retain 80% and 82% of the initial efficiency after storage for 1400 h in air and 700 h in 85 °C, respectively. The results show that 3-Hh could be a promising multifunctional interface material to further enhance the efficiency and the stability of perovskite solar cells.