Cl离子掺杂对钙钛矿薄膜结构及光学性能的影响

Effect of Cl Ion Doping on Structure and Optical Properties of Perovskite Thin Films

有机-无机杂化钙钛矿光吸收层薄膜的结构、形貌及结晶度对电池的光电性能起决定性作用。采用一步溶液法通过改变CH_3NH_3I和PbCl_2的摩尔比调控钙钛矿前驱体溶液中Cl离子的掺杂量,从而制备钙钛矿光吸收层薄膜。利用荧光光谱(PL)、X射线衍射(XRD)、扫描电子显微镜(SEM)及EDS能谱分别对钙钛矿溶液的荧光性能、薄膜的结构、表面形貌及反应后Cl离子的含量进行表征。结果表明,随着CH_3NH_3I和PbCl_2的摩尔比的增加,前驱体溶液的荧光强度逐渐减弱(激发波长为325 nm);晶体结构由立方相CH_3NH_3PbCl_3转换成了纯的四方相CH_3NH_3PbI_3钙钛矿薄膜,晶粒尺寸增大,晶格应变随之增加;表面覆盖率逐渐升高,薄膜表面无针状结构出现;薄膜中Cl离子的含量逐渐减少,改善了薄膜的质量。

The organic-inorganic hybrid perovskite thin film is used to the light absorbing layer of thin film solar cell.Its structure,morphology and degree of crystallinity play a key role in the photovoltaic properties.The method of one-step solution was adopted to modify the doping amount of Cl ions in the perovskite precursor solution by changing the molar ratio of CH 3NH 3I and PbCl 2 to prepare the perovskite light-absorbing layer film.The fluorescence properties,structure,surface morphology and the content of Cl ions of perovskite thin films were characterized by PL,XRD、SEM and EDS,respectively.The results indicate that with the increase of the molar ratio of CH 3NH 3I and PbCl 2,the fluorescence intensity of the precursor solution decrease gradually(excitation wavelength is 325 nm).The crystal structure from cubic phase CH 3NH 3PbCl 3 transformed to pure tetragonal CH 3NH 3PbI 3 perovskite film.As a result,the lattice strain became larger and larger.The surface coverage increased gradually and no needle structure appeared,with the content of Cl ions in the film decreases gradually,the quality of the film improves.