Electric field-induced broadening and narrowing of an exciton absorption band have been observed to depend on the polarity of the applied electric field for methylammonium lead triiodide perovskite (MAPbI3) as a thin film sandwiched between a conducting film of fluorine-doped tin oxide (FTO) and an insulating film of poly(methyl methacrylate) (PMMA). The width of the absorption band increased or decreased when the direction of the applied field was toward FTO or PMMA, respectively, indicating that the spectral broadening and narrowing become switchable on altering the direction of the applied electric field. When titanium oxide (TiO2) in a compact layer was introduced between the MAPbI3 and FTO layers, the linear electric field effect that depended on the polarity was either not observed or decreased significantly although the quadratic field effects on the exciton absorption band were similarly observed with or without the TiO2 layer.

中文翻译：

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通过改变外加电场的极性在 CH3NH3PbI3 薄膜的激子吸收带的光谱加宽和变窄之间切换

已经观察到电场诱导的激子吸收带的加宽和变窄取决于甲基铵三碘化铅钙钛矿（MAPbI3）作为夹在掺氟氧化锡（FTO）导电膜之间的薄膜的施加电场的极性。 ）和聚（甲基丙烯酸甲酯）（PMMA）绝缘膜。当外加电场的方向分别朝向 FTO 或 PMMA 时，吸收带的宽度增加或减小，表明光谱加宽和变窄在改变外加电场方向时变得可切换。当在 MAPbI3 和 FTO 层之间引入致密层中的氧化钛 (TiO2) 时，