Next generation CIGS for solar cells

An overview is presented of the PV-ACIST project. The goal of this project is to demonstrate proof-of-concept of next generation CuIn1-xGax(SySe1-y)(2) (CIGS)-based solar cells. The first phase of the project began with a theoretical analysis of the potential of tandem-junction devices. This analysis showed that efficiencies could exceed 25% based constituent junctions comparable to the best achieved in single CIGS junctions. Subsequent efforts have focused on development and characterization of the materials and processes necessary to achieve the wide-gap device portion of the tandem structure and on modeling of device results based on both wide and narrow gap materials. Results to date have included demonstration of wide gap devices, characterization of the diffusivity of Ga in CIGS under various process conditions, characterization and modeling of the conduction properties of ideal CIGS, and model results explaining the ''red kink'' effect in certain high-performance CIGS solar cells.