Surface oxygen vacancy regulation via Li-doped in MOF-derived mesoporous TiO2 for printable mesoscopic perovskite solar cells

Abstract

The mesoporous TiO₂ displays low conductivity and abundant oxygen vacancies (OVs) defects, leading to reduced carrier extraction and affecting the power conversion efficiency (PCE) of perovskite solar cells (PSCs). In this study, we investigate the electron transport layer of mesoporous TiO₂ derived from Ti-MOFs with Li-doped, employing a strategy to regulate the OVs on the TiO₂ surface to enhance device performance. Experimental results demonstrate that Li doping increases the conductivity of TiO₂, improves the energy level alignment between the TiO₂ and perovskite interfaces, and alleviates the residual stress in the perovskite. Theoretical calculations indicate that Li doping can inhibit the formation of OVs, reduce the band gap of TiO₂, and decrease the surface energy of the interface, thereby enhancing carrier extraction. Ultimately, carbon-based printable mesoscopic PSC by Li-doped achieved a champion PCE of 18.07 % and improved long-term stability.