Enhancement of short-circuit current density in Cu₂O/ZnO heterojunction solar cells

This study reports the achievement of a high short-circuit current density (J_sc) of 9.53 mA/cm²for low-cost electrodeposited (ED) semi-transparent Cu₂O/ZnO nanorod (NR) solar cells. High-quality chemical-bath-deposited ZnO NRs that align with the carrier collection path were used to replace the traditional sputtered ZnO film. An almost four-fold increase (from 1.63 to 6.41 mA/cm²) in J_scwas obtained with the NRs compared to the level obtained with a sputtered ZnO thin film cell. Decreased the ED Cu₂O absorber film thickness is able to compensate for the recombination loss that results from Cu₂O's short minority carrier drift and diffusion length (both on the order of 100 nm), further boosting J_scto 7.77 mA/cm². Additional photo-generated carriers were created for the semi-transparent solar cells when a silver mirror was deposited on the backside of the glass; this further enhanced absorption and improved J_scto 9.53 mA/cm². This is the highest J_scvalue reported to date for a low-cost ED Cu₂O/ZnO solar cell.