Effect of the deposition process of window layers on the performance of CIGS solar cells

The effects of the formation process of transparent conducting electrodes on the performance of Cu(In,Ga)Se-2 thin film solar cells were examined. B:ZnO and (Ga,Al):ZnO thin films deposited using metalorganic chemical vapor deposition (MOCVD) and magnetron sputtering, respectively, were compared in terms of the unit thin films and solar cell device performance. Both unit films formed under optimized process conditions showed similar electrical resistance, whereas the optical reflectance of B:ZnO by MOCVD was superior to that of the sputtered film. In the case of the B:ZnO film deposited on the absorber layer, the surface roughness became greater than the unit film on the test glass. The short-circuit current of the solar cell fabricated with B:ZnO was 3% higher than that with (Ga,Al):ZnO due to the enhanced light scattering. The junction quality and defect chemistry were identical in both devices, which suggests that there was no plasma damage due to sputtering. (C) 2017 Elsevier B.V. All rights reserved.