CZTS Solar Cell

Cu2ZnSnS4 (CZTS) solar cells have drawn attention because of its potential of delivering high energy conversion efficiency which is comparable to CIGS solar cells but using earth-abundant, cheaper raw materials Cu Zn and Sn and S rather than In and Ga. The material cost of CZTS is roughly around 1/5 of CIGS. Currently, the efficiency of CZTS solar cell (champion efficiency of 11%) is still far behind of CIGS (>20%). Issues including the quality of absorber and quality of interfaces at the heterojunction and back contact of CZTS device are believed to be the key to enhance the performance of the solar cells. A schematic showing the basic device structure (figure at left) and challenges of obtaining high quality CZTS absorber (figure at right) is shown below.

The quality of CZTS is strongly dependent on the fabrication procedure including precursor and sulfurization process. A high quality CZTS light absorber film should possess desirable properties including kesterite CZTS phase with highly ordered Cu-Zn in the material crystal structure and minimum defects and defect complexes. In case of the heterojunction interfaces in the solar cells, the band alignment and defects acting as recombination centre needs to be optimised and minimised. Our research aims to address these problems through in-depth understanding of the origin of defects and their properties by using cut-edge characterisation methods to enable develop creative strategies in the material fabrication process to eliminate the detrimental defects. Our ultimate goal is to fabrication high efficiency CZTS solar cells with comparable efficiency to CIGS to achieve cost-effective solar electricity by harnessing sun light to satisfy the energy demand of our globe with no carbon emission.