Solution-deposited pure selenide CIGSe solar cells from elemental Cu, In, Ga, and Se

A novel, robust and low-toxicity solution route to deposit CIGSe thin films for solar cell applications is proposed. The solvent mixture of 1,2-ethanedithiol and 1,2-ethylenediamine is employed for the first time to simultaneously dissolve elemental Cu, In, Ga, and Se, forming the CIGSe precursor solution. With this solution-processed CIGSe thin film solar cell, a power conversion efficiency of 9.5% has been achieved.