Reflection optimization for alternative thin-film photovoltaics

The recent improvements in efficiencies for kesterite (copper zinc tin selenide, CZTS) devices warrant an investigation into how the kesterite device stack can best be capped to minimize losses due to reflection. Additionally, ongoing efforts to replace the cadmium sulfide (CdS) layer in copper indium gallium selenide (CIGS)-based devices, most notably with zinc sulfide (ZnS), need to be accompanied by a similar investigation into how to best finish a CIGS/ZnS stack to minimize reflection losses. An optical analysis of how CZTS/CdS and CIGS/ZnS devices reflect light has been performed for the purpose of optimizing the transparent conducting oxide and antireflection layers for each stack. This research addresses what is similar and what is different between the alternative stacks and the routine CIGS/CdS stack and how to best reduce the reflection losses for each situation.