Influence of coevaporation process on CIGS solar cells with reduced absorber thickness and current enhancement with periodically textured glass substrates

Abstract : This study shows the fabrication of CIGS solar cells with various absorber thicknesses synthesized with two different methods: the classical 3-stages coevaporation process and a 1-stage coevaporation process. Structural characteristics and photovoltaics properties as function of absorber thickness are described. 1-stage coevaporation process gives lower efficiencies for CIGS solar cells with nominal absorber thickness ($\sim$2000 nm) but performs similarly or even better when the absorber thickness is decreased down to 600 nm. Periodically textured glass substrates with different feature sizes have been fabricated and used to increase current in 1-stage coevaporated CIGS solar cells. A current improvement up to 4.1 mA·cm$^{−2}$ (6% relative) has been obtained leading to an increase in efficiency up to 5% relative. A maximum increase has been found when texturation size is similar to CIGS absorber thickness.