Efficient CdTe Nanocrystal/TiO2 Hetero-Junction Solar Cells with Open Circuit Voltage Breaking 0.8 V by Incorporating A Thin Layer of CdS Nanocrystal
Xianglin Mei,
Bin Wu,
Xiuzhen Guo,
Xiaolin Liu,
Zhitao Rong,
Songwei Liu,
Yanru Chen,
Donghuan Qin,
Wei Xu,
Lintao Hou,
Bingchang Chen
Affiliations
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
Xiuzhen Guo
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
Zhitao Rong
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Songwei Liu
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Yanru Chen
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
Wei Xu
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Lintao Hou
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Siyuan Laboratory, Department of Physics, Jinan University, Guangzhou 510632, China
Bingchang Chen
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China
Nanocrystal solar cells (NCs) allow for large scale solution processing under ambient conditions, permitting a promising approach for low-cost photovoltaic products. Although an up to 10% power conversion efficiency (PCE) has been realized with the development of device fabrication technologies, the open circuit voltage (Voc) of CdTe NC solar cells has stagnated below 0.7 V, which is significantly lower than most CdTe thin film solar cells fabricated by vacuum technology (around 0.8 V~0.9 V). To further improve the NC solar cells’ performance, an enhancement in the Voc towards 0.8–1.0 V is urgently required. Given the unique processing technologies and physical properties in CdTe NC, the design of an optimized band alignment and improved junction quality are important issues to obtain efficient solar cells coupled with high Voc. In this work, an efficient method was developed to improve the performance and Voc of solution-processed CdTe nanocrystal/TiO2 hetero-junction solar cells. A thin layer of solution-processed CdS NC film (~5 nm) as introduced into CdTe NC/TiO2 to construct hetero-junction solar cells with an optimized band alignment and p-n junction quality, which resulted in a low dark current density and reduced carrier recombination. As a result, devices with improved performance (5.16% compared to 2.63% for the control device) and a Voc as high as 0.83 V were obtained; this Voc value is a record for a solution-processed CdTe NC solar cell.
