Performance Enhancement of Graded CIGS Solar Cell with MoTe2 as Transition Layer and BSF Contact

Thin-film solar cell devices are gradually picking up in the commercial renewable energy space due to their lower energy payback period. CIGS (copper indium gallium selenide) based solar cells are one of the major contenders due to their higher conversion efficiency. Bandgap tuning through Ga grading if CIGS solar cells are one of the proven methods to improve its performance parameters. To increase the overall quantum efficiency of the device front grading (FG) i.e. stacking up the high band gap top layer followed by lower band gap bottom layer is used. To alleviate the intrinsic issue of minority carrier recombination in FG CIGS the use of p-Si and MoTe
2
as BSF(back surface field) contact have been evaluated. The MoTe
2
as an interfacial and BSF layer has been proposed. To solve dual issues of inter-layer elemental inter-diffusion during high temperature annealing and to restrict minority carrier recombination at the back contact. The best cell performance parameters Voc as 0.97V, J
sc
as 40.64mA/cm
²
, FF as 76.81% and efficiency(η) as 30.43% have been achieved using wx-AMPS simulation program.