Tunable Hole‐Selective Transport by Solution‐Processed MoO<sub>3−<i>x</i></sub> Via Doping for <i>p</i>‐Type Crystalline Silicon Solar Cells
Yaju Wei, Guoqiang Yu, Guohui Luo, Fu Wang, Wuqi Liu, Tao Wang, Haonan Xu, Xiaoping Wu, Lingbo Xu, Ping Lin, Xiaodong Zhu, Xuegong Yu, Peng Wang, Can Cui
Abstract
Molybdenum oxide (MoO 3− x , x < 3) has been successfully used as an efficient hole‐selective contact material for crystalline silicon heterojunction solar cells. The carrier transport capability strongly depends on its work function, that is, oxygen vacancies; however, there are lack of effective methods to modulate the multiple oxidation states. Herein, the oxidation states of solution‐processed MoO 3− x by doping Nb 5+ to improve its hole‐selective contact performance with silicon are tuned. With the optimum doping concentration of 5%, both the reduced Mo 5+ and oxygen vacancies increase, resulting in a decrease in the contact resistivity between the MoO 3− x film and p ‐type silicon from 161.1 to 62.9 mΩ·cm 2 and an increase of the effective carrier lifetime from 165.4 to 391.0 μs simultaneously. Similarly, the doping of Ta 5+ or V 5+ in MoO 3− x improves the passivated contact performance with silicon, while the former increases the concentration of oxygen vacancies and the latter reduces it. The solar cell with the structure of Ag/MoO 3− x :Nb/ p ‐Si exhibits a conversion efficiency of 18.37%, which is the highest so far reported for the solution‐processed MoO 3− x /silicon heterojunction. This work demonstrates a feasible strategy of tuning hole selectivity in MoO 3− x by doping for high‐efficiency solar cells and other optoelectronic device applications.