Self-assembled manganese acetate@tin dioxide colloidal quantum dots as an electron-transport layer for efficient and stable perovskite solar cells

Abstract

An SnO₂ electron-transport layer (ETL) is a critical and mainstream component utilized in perovskite solar cells (PSCs) on account of its exceptional photoelectric performances and low-temperature fabrication process. Nevertheless, a significant number of defects on the surface of SnO₂ quantum dots (QDs) can lead to QD agglomeration in dispersion and poor film quality, ultimately compromising the power conversion efficiency (PCE) and stability of devices. In this study, we developed multifunctional manganese acetate (Mn(Ac)₂)-stabilized SnO₂ quantum dots (Mac-SnO₂ QDs) and utilized them to prepare ETLs for PSCs. The CO groups of Mn(Ac)₂ can terminate the Sn⁴⁺ dangling bonds on Mac-SnO₂ QDs, thereby preventing QD agglomeration, facilitating the preparation of a uniform film with good electrical properties. In addition, Mn²⁺ can permeate upward into the perovskite film, passivating I⁻ at the grain boundary and reducing perovskite bulk defects. Moreover, the perovskite grown on Mac-SnO₂ releases residual stress, which can improve device performance and stability. As a consequence, Mac-SnO₂ PSCs achieved a high PCE of 23.36% with improved stability. This successful approach of utilizing an organic acid salt to modify SnO₂ QDs provides a facile and efficient strategy for enhancing the efficiency and stability of PSCs.