Dopamine-crosslinked TiO2/perovskite layer for efficient and photostable perovskite solar cells under full spectral continuous illumination

Even though TiO 2 is the most widely used electron transport layer (ETL) in high-efficiency perovskite solar cells (PSCs), ultraviolet photocatalysis and existence of intrinsic oxygen vacancies result in interfacial charge recombination and poor long-term photo-stability for TiO 2 -based PSCs under full spectral continuous illumination. To solve the issues, here we report dopamine-capped TiO 2 nanoparticles as ETL via chelating effect to improve interfacial binding with perovskite active layer. The introduction of dopamine can substantially reduce oxygen vacancies and suppress deep trap states within TiO 2 . In addition, the terminal amino groups in dopamine can passivate the uncoordinated Pb atoms and decrease the Pb-I/Br antisite defects on the interface of perovskite/TiO 2 . As an interfacial crosslinking agent, dopamine can not only reduce charge-accumulation and charge-recombination rate, but also increase charge-extraction efficiency at the TiO 2 and perovskite interface. Based on the dopamine-capped TiO 2 nanoparticles surface, the corresponding planner Cs 0.05 FA 0.81 MA 0.14 PbI 2.55 Br 0.45 PSCs deliver a power conversion efficiency of nearly 21% with negligible hysteresis . Moreover, unencapsulated devices retain 80% of their initial performance after 1200 h operation under constant full-sun illumination in nitrogen atmosphere. Ideally, this chemical-bath-deposited dopamine-modified TiO 2 provides an effective commercialized route for efficient and photostable planar PSCs.