Controlling Defect of Kesterite—Precursor, Annealing, Post-Treatment Designs

Increasing the diversity of viable photovoltaic materials is critical to allow greater adaptability as the technology continues to expand and develop not only for further increasing the efficiency but also fulfill various application areas. Kesterite, is a green energy material to capitalize this opportunity, utilizing sustainable earth-abundant and non-toxic materials for renewable energy conversion. The quaternary compound of kesterite offers significant flexibility and tunability in its optical and electrical properties, but also introduces complexities in defect management. Controlling defect formation has been linked to key breakthroughs in improving kesterite solar cell efficiency in recent years. Precursor design (e.g. component, structure), kinetic control of annealing strategies have shown effective in controlling defect. This include not only reducing the detrimental defect such as Sn related defect cluster, but also enhancing the self-doping defect to tune the carrier concentration. Beyond that, we recently discover that post-treatment can also be used to modulate the defect of kesterite, tuning the carrier concentration of the bulk in a favorable way and resulting in enhanced photo-generated carrier collection. This talk will discuss the defect control strategies that resulted in efficiency improvement in pure sulphide kesterite solar cells.