Interfacial charge-transfer engineering by ionic liquid for high performance planar CH3NH3PbBr3 solar cells

摘要

The energy barrier at the CH3NH3PbBr3/TiO2 interface hinders the electron transfer from CH3NH3PbBr3 to compact TiO2 (cp-TiO2).Ionic liquid (IL),that forms dipoles pointing away from TiO2,can adjust the work function of TiO2 resulting in suitable energy level for charge transfer from CH3NH3PbBr3 to TiO2.The time-resolved photoluminescence spectroscopy (TRPL) measurements confirm faster electron transfer from the CH3NH3PbBr3 film to TiO2 after modification by IL,Solar cells based on IL modified cp-TiO2 demonstrate efficiency of ～6％,much higher than the devices (0.2％) fabricated using untreated cp-TiO2 as the electron transport layer.