Sn类钙钛矿太阳电池薄膜的掺杂改性研究

采用一步法分别制备了Sn类CH3NH3Sn I3和Pb类CH3NH3Pb I3钙钛矿太阳电池薄膜材料,并对其表面形貌、微观结构、吸收光谱和电池器件性能进行了表征和测试。研究结果表明:Sn类钙钛矿材料的吸收光谱相对于Pb类钙钛矿材料发生了明显的红移,吸收截止波长从800 nm上升到950 nm左右,光学带隙由1.45 e V降低至1.21 e V左右;Sn类钙钛矿材料的光谱吸收范围明显扩大,但吸收强度有所降低,相应太阳电池器件的光电转换效率也明显低于Pb类钙钛矿太阳电池,分别为2.05%和6.71%。而Br的掺杂可使Sn类钙钛矿材料带隙变宽,吸收光子能量增大,电池器件的开路电压也相应提高。当Br含量由0增加至完全替代I时,Sn类钙钛矿材料逐渐由黑褐色转变为黄色,光学带隙增大至1.95 e V,但吸收截止波长由950 nm降低至650nm。值得提及的是当Br含量为0.5时,电池器件的光电转换效率可由最初的2.05%提升至2.94%。

Doping Modification of Stannic Perovskite Based Thin Films for Solar Cell Applications

The plumbic and stannic perovskite solar cell materials such as CH₃NH₃SnI₃ and CH₃NH₃PbI₃ were obtained by one step preparation with the surface morphology, microstructure, spectral absorption and device performance were investigated respectively. The spectral absorption of stannic perovskite material were found to expand wider and have an obvious red-shift compared to plumbic perovskite, with the absorption edge increased from 800 to 950 nm and the optical band gap reduced from 1.45 to 1.21 eV. But the conversion efficiency of stannic perovskite solar cell demonstrated significantly lower than that of plumbic perovskite, 2.05% and 6.71% respectively, due to a downshift of absorption intensity. However, bromine (Br) doping could broaden the band gap and thus give rise to the open circuit voltage of solar cell device accordingly. As the doping content increased from 0 to be totally replacement of iodine, the color of stannic perovskite turned gradually from dark brown to yellow, and the optical band gap increased up to 1.95 eV. At the same time, a blue shift of spectra absorption was observed, reducing from 950 to 650 nm. Noteworthy is that the solar cell conversion efficiency increased from initial 2.05% to 2.94% at the doping content of 0.5.