Study of Inx(O,OH,S)y buffer layer effect on CIGSe thin film solar cells

•Inx(O,OH,S)y buffer layer was made by using CBD method.•The CBD condition had effects on CIGSe cell efficiency.•Higher concentrated S in the CBD solution results in killing some interface defects.

Inx(O,OH,S)y buffer layer has been applied to Cu(In,Ga)Se2(CIGSe) solar cell by chemical bath deposition (CBD). The cell efficiency was observed to be dependant on film growth mode of Inx(O,OH,S)y buffer layer, which was affected by the CBD conditions such as sulfur chemical concentration and deposition time. The fabricated solar cell showing higher conversion efficiency was observed to have non-porous and uniform texture of buffer, whereas the lower conversion efficiency cells were found to have fibrous texture or detached texture of buffer. The fibrous texture and the detached texture induced high series resistance and lower shunt resistance, respectively, which all resulted in lower cell efficiency with reduced fill factor. External quantum efficiency and temperature dependence of open circuit voltage measurements revealed that the lower efficiency cells suffered from higher interface recombination loss due to the related defects.