Interface passivation and band alignment of high efficiency Cu(In, Ga)Se2 solar cells: Application of Mo(OxSe1-x)2 buffer layer at Mo/ Cu(In, Ga) Se2 interface

Cu(In,Ga)Se2(CIGSe) solar cell is one of the most promising thin film solar cells with high photoelectric con-version efficiency. However, the efficiency is still far below the thermodynamic Shockley-Queisser (SQ) limit. Interfacial recombination is the main factor restricting the performance of CIGSe solar cells. In this work, oxygen -doped Mo(OxSe1-x)2 was employed to study the effect of Mo/CIGSe interfacial recombination. SCAPS simulation and first-principles calculation were used in this work. The band gap of Mo(OxSe1-x)2 was adjusted by changing the content of oxygen, the band alignment of Mo/Mo(OxSe1-x)2 interface and Mo(OxSe1-x)2/CIGSe interface were optimized. The back interface recombination was effectively reduced by using a thickness of 10-70 nm Mo (OxSe1-x)2 with an oxygen doping concentration of 12.5%-50.0% and the performance of CIGSe solar cells was improved. Finally, the conversion efficiency was improved from 15.80% to 24.35% with oxygen doping con-centration of 25% and Mo(OxSe1-x)2 layer with thickness of 40 nm.