Properties of thin film CuGa{sub}0.2In{sub}0.8Se{sub}2/CdO heterojunction

摘要

Device quality CuGa{sub}xIn{sub}(1-x)Se{sub}2 layers have been deposited using chemical spray pyrolysis. These layers were used to make thin film heterojunctions with the configuration glass/Mo/CuGa{sub}0.2In{sub}0.8Se{sub}2/CdO using sputtered CdO as the window layer. The devices were characterised using current-voltage, capacitance-voltage and spectral response measurements in order to evaluate the junction and cell performance. The diodes had a saturation current density of 9.4×10{sup}-7 Acm{sup}-2, an ideality factor of 1.85 and with a barrier height of 0.85 eV. The current transport across the junction was modelled as a composite of tunnelling and interface recombination transport mechanisms. The best cells had conversion efficiencies of 2.3% with quantum efficiencies > 70%. The device efficiency was limited by series resistance. This is the first time that photovoltaic solar cells have been made using sprayed CuGa{sub}xIn{sub}(1-x)Se{sub}2 thin films as absorber layers.