摘要
The performance of Cu(In,Ga)Se2 (CIGS) solar cells was significantly improved by introducing a layered WSe2 thin film as a rear passivation layer in the back contact region. A vertically aligned stacking channel of the WSe2 thin film was obtained by converting a WOx thin film using a plasma-assisted selenization process. With the insertion of the WSe2 layer, we observed a notable accumulation of Ga at the rear side of the CIGS absorber layer, facilitated by the vertically channel-stacked WSe2 thin film. Increased open-circuit voltage is attributed to the reconstruction of the band alignment due to the modified Ga concentration profile, effectively mitigating electron flowing toward back contact and recombination within the back contact region of the CIGS solar cell. Furthermore, a favorable conductivity along the channels of the vertically channel-stacked WSe2 thin film and a steeper [Ga]/([Ga] + [In]) (GGI) gradient provide significant enhancements in short-circuit current density. The solar energy conversion efficiency of the CIGS solar cell, fabricated via a sequential process with elemental Se vapor, was boosted from 15.08 % to 17.06 %. The remarkable enhancement highlights the potential of employing two-dimensional materials as passivation layers in photovoltaic applications.
[Display omitted]
•A vertically stacked WSe2 thin film, converted from WOx via plasma-assisted selenization, was successfully demonstrated as a rear passivation layer for CIGS solar cells.•The insertion of the WSe2 layer led to notable Ga accumulation at the rear of the CIGS, boosting solar conversion efficiency from 15.08% to 17.06%.