Application of CVD graphene as transparent front electrode in Cu(In,Ga)Se2 solar cell

Graphene is a promising material to be used as transparent conducting electrode (TCE) due to its high optical transmittance and conductivity. In this work, we present a novel TCE structure for the Cu(In,Ga)Se₂ (CIGS) solar cell in which a AuCl₃ doped graphene film grown by chemical vapor deposition (CVD) with a thin layer of PMMA coating was used to replace the ZnO:Al (AZO) film. The Ni/Al/Ni metal grid was directly deposited on the intrinsic high resistivity ZnO (i-ZnO) buffer layer. And large area (~ 0.5 cm²) PMMA/graphene layer was transferred to contact both metal grid and i-ZnO. Our findings demonstrate that FF, J_sc and PCE will be improved when silver nanowires are present at the graphene/i-ZnO interface in the CIGS solar cell. To further increase the solar cell performance, the pattern of the metal grid was also simulated and optimized.