Electrochemical Studies on the Electron Disorder in Cuprous Selenide

Abstract The ratio of copper‐to‐selenium in cuprous selenide has been determined as function of the copper activity in the selenide at 435°C with the help of coulometric titrations. At 435°C the homogeneity range of cuprous selenide extends from a Cu/Se ratio of 1.998 to a value lower than 1.860. Analysis of the experimental data shows that the change of the chemical potential of copper by a change of the composition is only given by a change of concentration of the defect electrons or of the quasifree electrons. From these studies, the energy gap in coprous selenide is at least 0.37 eV.