A review of the challenges facing kesterite based thin film solar cells

The best literature reported kesterite sulfide Cu₂ZnSnS₄ and selenide Cu₂ZnSnS₄ thin film solar cell device performance and photocurrent spectra have been compared with their analogous chalcopyrite CulnS₂ and CulnSe₂ devices. Reasons for the kesterites worse performance have been analyzed in terms of (i) phase composition and morphology (ii) opto-electronic properties and (iii) layer interfaces. A new electrodepositon and annealing process is presented for producing Cu₂ZnSnS₄ absorber layers that gave a highest power conversion efficiency of over 3.2 %. Furthermore photoluminescence spectra of Cu₂ZnSnS₄ single crystals showing defect related is presented for the first time.