Spectrum-Dependent Spiro-OMeTAD Oxidization Mechanism in Perovskite Solar Cells.
We propose a spectrum-dependent mechanism for the oxidation of 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) with bis(trifluoromethane)sulfonimide lithium salt (LiTFSI), which is commonly used in perovskite solar cells as the hole transport layer. The perovskite layer plays different roles in the Spiro-OMeTAD oxidization for various spectral ranges. The effect of oxidized Spiro-OMeTAD on the solar cell performance was observed and characterized. With the initial long-wavelength illumination (>450 nm), the charge recombination at the TiO2/Spiro-OMeTAD interface was increased due to the higher amount of the oxidized Spiro-OMeTAD. On the other hand, the increased conductivity of the Spiro-OMeTAD layer and enhanced charge transfer at the Au/Spiro-OMeTAD interface facilitated the solar cell performance.
Department of NanoEngineering, University of California San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
Shen
S
Wang
Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States.
Wen
W
Yuan
Department of NanoEngineering, University of California San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States.
Ying Shirley
YS
Meng
charge recombination; impedance spectroscopy; p-doping; perovskite solar cells; solid state; spectrum