Rationally Controlled Synthesis of CdSexTe1−x Alloy Nanocrystals and Their Application in Efficient Graded Bandgap Solar Cells
Shiya Wen,
Miaozi Li,
Junyu Yang,
Xianglin Mei,
Bin Wu,
Xiaolin Liu,
Jingxuan Heng,
Donghuan Qin,
Lintao Hou,
Wei Xu,
Dan Wang
Affiliations
Shiya Wen
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Miaozi Li
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Junyu Yang
Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Department of Physics, Jinan University, Guangzhou 510632, China
Xianglin Mei
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Bin Wu
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Xiaolin Liu
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Jingxuan Heng
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Donghuan Qin
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Lintao Hou
Siyuan Laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Department of Physics, Jinan University, Guangzhou 510632, China
Wei Xu
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Dan Wang
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
CdSexTe1−x semiconductor nanocrystals (NCs), being rod-shaped/irregular dot-shaped in morphology, have been fabricated via a simple hot-injection method. The NCs composition is well controlled through varying molar ratios of Se to Te precursors. Through changing the composition of the CdSexTe1−x NCs, the spectral absorption of the NC thin film between 570–800 nm is proved to be tunable. It is shown that the bandgap of homogeneously alloyed CdSexTe1−x active thin film is nonlinearly correlated with the different compositions, which is perceived as optical bowing. The solar cell devices based on CdSexTe1−x NCs with the structure of ITO/ZnO/CdSe/CdSexTe1−x/MoOx/Au and the graded bandgap ITO/ZnO/CdSe(w/o)/CdSexTe1−x/CdTe/MoOx/Au are systematically evaluated. It was found that the performance of solar cells degrades almost linearly with the increase of alloy NC film thickness with respect to ITO/ZnO/CdSe/CdSe0.2Te0.8/MoOx/Au. From another perspective, in terms of the graded bandgap structure of ITO/ZnO/CdSe/CdSexTe1−x/CdTe/MoOx/Au, the performance is improved in contrast with its single-junction analogues. The graded bandgap structure is proved to be efficient when absorbing spectrum and the solar cells fabricated under the structure of ITO/ZnO/CdSe0.8Te0.2/CdSe0.2Te0.8/CdTe/MoOx/Au indicate power conversion efficiency (PCE) of 6.37%, a value among the highest for solution-processed inversely-structured CdSexTe1−x NC solar cells. As the NC solar cells are solution-processed under environmental conditions, they are promising for fabricating solar cells at low cost, roll by roll and in large area.
