Efficiency and Stability Enhancement in Perovskite Solar Cells by Inserting Lithium-Neutralized Graphene Oxide as Electron Transporting Layer

This work proposes a new perovskite solar cell structure by including lithium-neutralized graphene oxide (GO-Li) as the electron transporting layer (ETL) on top of the mesoporous TiO2 (m-TiO2) substrate. The modified work-function of GO after the intercalation of Li atoms (4.3 eV) exhibits a good energy matching with the TiO2 conduction band, leading to a significant enhancement of the electron injection from the perovskite to the m-TiO2. The resulting devices exhibit an improved short circuit current and fill factor and a reduced hysteresis. Furthermore, the GO-Li ETL partially passivates the oxygen vacancies/defects of m-TiO2 by resulting in an enhanced stability under prolonged 1 SUN irradiation.