In organolead halide perovskite solar cells (PSCs), interfacial properties between the perovskite and charge transport layers are the critical factors governing charge extraction efficiency. In this study, the effect of interfacial energetics between two-step spin-coated methylammonium lead iodide (MAPbI3) with different methylammonium iodide (MAI) concentrations and C60 on the charge extraction efficiency is investigated. The electronic structures of perovskite films are significantly varied by the MAI concentrations due to the changes in the residual precursor and MA+ defect content. As compared to the optimum PSCs with 25 mg mL-1 MAI, PSCs with other MAI concentrations show significantly lower power conversion efficiencies and severe hysteresis. The energy level alignment at the C60/MAPbI3 interface determined by ultraviolet and inverse photoelectron spectroscopy measurements reveals the origin of distinct differences in device performances. The conduction band offset at the C60/MAPbI3 interface plays a crucial role in efficient charge extraction in PSCs.
Bibliographical noteFunding Information:
This study was supported by the National Research Foundation of Korea [NRF-2015R1C1A1A01055026, 2017R1A2B4002442, and 2017R1A5A1014862 (SRC program: vdWMRC center)] and Samsung Display Company and an Industry−Academy joint research program between Samsung Electronics and Yonsei University.
© 2017 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physical and Theoretical Chemistry