Studies on ZnS 0.5Se 0.5 buffer based thin film solar cells

Abstract

ZnS 0.5Se 0.5 has been proposed as a novel buffer layer, alternative to CdS for solar cell application. ZnS 0.5Se 0.5 layers were deposited at 300 °C using close-spaced evaporation. The layers exhibited cubic structure with a sharp (111) reflection. The films showed an optical transmittance > 80% with an energy band gap of 3.01 eV and the electrical resistivity of the films was ~ 10 5 Ωcm. CuInS 2 (CIS) films synthesized by sulphurisation process of rf sputtered Cu/In precursor layers formed on Mo coated glass were used as absorber. Structural, optical and electrical studies were performed to characterize the synthesized CuInS 2 films. Thin film solar cells were fabricated by depositing a thin ZnS 0.5Se 0.5 buffer layer onto the Glass/Mo/CuInS 2 with sprayed ZnO:Ga as a window layer. The interfacial properties of the resulting heterojunction were studied using current–voltage (I–V), capacitance–voltage (C–V) and spectral response measurements and the results were discussed.