Influence of Conduction Band Offset between Cu(In,Ga)Se2 Absorber and Zn1-xMgxO Buffer in Zn1-xMgxO:Al/Zn1-xMgxO/CdS/Cu(In,Ga)Se2 Solar Cell

The performance of Cu(In,Ga)Se₂ (CIGS) thin-film solar cells is significantly influenced by the conduction band offset (CBO) at the interface between the CIGS absorber and the buffer layer. This study investigates the impact of varying the conduction band alignment in Zn₁₋ₓMgₓO buffer layers with different Mg compositions (x) on the efficiency of Zn₁₋ₓMgₓO:Al/Zn₁₋ₓMgₓO/CdS/CIGS solar cells. By tuning the Mg content in Zn₁₋ₓMgₓO, the CBO at the CIGS/buffer interface is systematically modified, allowing for optimization of electron transport and recombination dynamics. Through experimental characterization and simulation, we identify an optimal CBO range that minimizes interfacial recombination while maintaining efficient carrier collection. The results demonstrate that precise control of the Zn₁₋ₓMgₓO bandgap is crucial for achieving high-efficiency solar cells, highlighting the potential of Zn₁₋ₓMgₓO as a tunable buffer layer material in next-generation CIGS photovoltaics.