Current status of transparent conducting oxide layers with high electron mobility and their application in Cu(In,Ga)Se2 mini-modules

Highlights: • Current progress with high mobility transparent conducting oxide films is described. • ZnO- and In₂O₃-based films are applied in Cu(In,Ga)Se₂ mini-modules. • The low process temperatures ( < 160 °C) of the films improve solar cell performance. • Compared with ZnO:Al or ZnO:B, spc-In₂O₃:W,H increases the short-circuit density. • A high certified conversion efficiency of 20.93% is achieved with spc-In₂O₃:W,H. -- Abstract: Transparent conducting oxide (TCO) films with high mobility and low carrier density exhibit both high conductivity and high transparency in the visible and near-infrared regions. TCO films that can be fabricated at low process temperatures provide opportunities to improve the performance of solar cells and to develop new optoelectronic applications. This paper describes the current status of ZnO- and In₂O₃-based TCO layers and their application in Cu(In,Ga)Se₂ mini-modules. The use of solid-phase crystallized In₂O₃:W,H layers instead of conventional ZnO:Al or ZnO:B layers increases both short-circuit current density and fill factor, and a high certified conversion efficiency of 20.93% has been achieved via this approach.