摘要
Germanium monoselenide(GeSe)is an emerging promising photovoltaic absorber material due to its attractive optoelectronic properties as well as non-toxic and earth-abundant constitutes.However,all previously reported GeSe solar cells rely on a superstrate configuration coupled with a CdS buffer layer,and suffer from unsatisfactory performance.Here we demonstrate that this low efficiency arises from the inevitable high-temperature treatment of p-n junction in superstrate configuration.This results in the diffusion of Cd atoms from CdS layer into GeSe film that introduces detrimental deep trap states inside the bandgap of GeSe(~0.34 eV below conduction band minimum).We adopt therefore a substrate configuration that enables the deposition of CdS atop pre-deposited polycrystalline GeSe film at room temperature,avoiding the Cd diffusion.By optimizing the annealing temperature of complete devices via a highthroughput screening method,the resulting substrate solar cells annealed at 150℃achieve an efficiency of 3.1%,two times that of the best previously reported superstrate GeSe results.
GeSe作为一种新兴光伏吸收层材料,具有良好的光电性能,且原料无毒、储量丰富.然而,以往报道的GeSe太阳能电池都采用顶衬结构,并使用CdS缓冲层,性能不理想.本文发现顶衬结构GeSe太阳能电池效率低下的原因是不可避免的p-n结高温热处理.这导致Cd原子从CdS层扩散到GeSe薄膜中,并在GeSe的禁带内引入有害的深缺陷态(位于导带底0.34 eV的位置).因此,我们首次制备了底衬结构GeSe太阳能电池.该结构可实现CdS层在多晶GeSe薄膜上的室温沉积,从而避免了有害的Cd扩散.通过进一步采用高通量的筛选方法来优化器件的退火温度,当退火温度在150℃时,器件效率达到最高的3.1%,为以前报道最佳结果的2倍.
作者
Shun-Chang Liu
Zongbao Li
Jinpeng Wu
Xing Zhang
Mingjie Feng
Ding-Jiang Xue
Jin-Song Hu
刘顺畅;李宗宝;吴劲澎;张星;冯明杰;薛丁江;胡劲松(Beijing National Laboratory for Molecular Sciences(BNLMS),CAS Key Laboratory of Molecular Nanostructure and Nanotechnology,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China;School of Material and Chemical Engineering,Tongren University,Tongren 554300,China;National Engncering Research Center for Adivanced Polymer Processing Technology,Zhenghou Untversty,Zhenghou 450002,China;University of Chinese Academy of Sclences,Beijing 100049,China)
基金
supported by the National Natural Science Foundation of China (21922512 and 21875264)
the Youth Innovation Promotion Association CAS (2017050)
