Evaluation of “rollover” in Cu(In,Ga)(Se,S)2 thin film solar cells using Suns-Vα measurements

The J-V characteristics of Cu(In,Ga)(Se,S)₂ solar cells are often distorted by so-called “rollover” effect. It is important to estimate the significance of rollover effect upon the device performance. Practical series resistance (R_s) obtained from conventional J-V measurements may consist of genuine R_s and apparent R_s, which arises from the rollover effect. We show that the combination of conventional J-V and Suns-V_α measurements can help to discriminate the rollover effect from genuine R_s variation of the devices.