title: Tunable Optical Properties and Charge Separation in CH3NH3Sn(x)Pb(1-x)I3/TiO2-Based Planar Perovskites Cells.
abstract: A sharp potential drop across the interface of the Pb-rich halide perovskites/TiO2 heterostructure is predicted from first-principles calculations, suggesting enhanced separation of photoinduced charge carriers in the perovskite-based photovoltaic solar cells. The potential drop appears to be associated with the charge accumulation at the polar interface. More importantly, on account of both the β phase structure of CH3NH3Sn(x)Pb(1-x)I3 for x < 0.5 and the α phase structure of CH3NH3Sn(x)Pb(1-x)I3 for x ≥ 0.5, the computed optical absorption spectra from time-dependent density functional theory (TD-DFT) are in very good agreement with the measured spectra from previous experiments. Our TD-DFT computation also confirms the experimental structures of the mixed Pb-Sn organometal halide perovskites. These computation results provide a highly sought answer to the question why the lead-based halide perovskites possess much higher power conversion efficiencies than the tin-based counterparts for solar-cell applications.
authors.affiliation: †School of Physics, State Key Lab Incubation Base of Photoelectric Technology and Functional Materials, and International Collaborative Center on Photoelectric Technology and Nano Functional Materials, Northwest University, Xi'an 710069, People's Republic of China.
authors.forename: Hong-Jian
authors.initials: HJ
authors.lastname: Feng
authors.forename: Tula R
authors.initials: TR
authors.lastname: Paudel
authors.forename: Evgeny Y
authors.initials: EY
authors.lastname: Tsymbal
authors.forename: Xiao Cheng
authors.initials: XC
authors.lastname: Zeng