Performance enhancement of perovskite solar cells based on a CdO-quantum dot/TiO2-nanocrystal array electron transport layer

Abstract An oriented TiO 2 nanocrystal array (TiO 2 -NA) shows a unique electron extraction capability for perovskite solar cells (PSCs) due to it having fewer grain boundaries and high crystallinity for effective charge collection. Based on these advantages, we prepared PSCs based on TiO 2 -NA mesoporous film (mp-film), and chose CdO quantum dots (QDs) as the modifier of the TiO 2 -NA mp-film. The diameter of a single TiO 2 -NA and the TiO 2 -NA gap were controlled by controlling the hydrothermal reaction time. The CdO-QDs/TiO 2 -NA mp-film, as the electron transporting layer (ETL), was prepared by successive ionic layer adsorption and the reaction-sintering method. In this work, oxidation state CdO QDs were first used as the modifier in the ETL of the PSC. We gradually optimized the CdO/TiO 2 -NA mp-film by controlling the hydrothermal reaction time of TiO 2 -NA to improve PSC performance. Infiltration of the perovskite absorber–submicrometer-thick rutile TiO 2 -NA mp-films with Spiro-MeOTAD yielded a strikingly high photoelectric conversion efficiency of 11.94% under AM 1.5G illumination. The dependence of photovoltaic performance and interfacial electronic behavior on the length of the CdO/TiO 2 -NA was also investigated.