Equivalent Circuit For AC Response of Cu(In,Ga)Se2 Thin Film Solar Cells
Ultrathin Cu(In,Ga)Se2 (CIGS) is desired to reduce production costs of CIGS solar cells. The present work aims to study the AC electrical response of standard-thick, ultrathin and passivated ultrathin devices. Admittance measurements allow to choose the AC equivalent circuit for each type of CIGS device. It is of utmost importance to understand the AC electrical behavior of each device, as the differences between reference thick, reference ultrathin and passivated ultrathin CIGS solar cells are yet to be fully understood. The analyses show a simpler AC equivalent circuit for the reference ultrathin device, which is explained by the lowered bulk recombination for thin film CIGS solar cells when compared with thick ones. The importance of shunts mitigation by the use of a passivation layer is also demonstrated, with a shunt resistance increase for the passivation device compared to both reference devices. ; Fundação para a Ciência e a Tecnologia (FCT) is acknowledged through: IF/00133/2015 and PD/BD/142780/2018. The European Union's Horizon 2020 research and innovation programme ARCIGS-M project (grant agreement no. 720887) is acknowledged. This research is also supported by NovaCell (028075) and InovSolarCells (029696) co-funded by FCT and the ERDF through COMPETE2020. We would like to thank Fundação Luso-Americana para o Desenvolvimento (FLAD) for support via project 2019/CON8/CAN19.