Abstract: High quantum yields of gain photocurrent provided by sandwiching an insulating layer in contact with a photoconductor between two electrodes, applying an electrical potential thereacross, and directing excitation light upon the photoconductor are increased by simultaneously impinging the photoconductor with infrared radiation during exposure to the excitation light where the photoconductor comprises selenium or a selenium alloy. In cyclical operation of gain photocurrent devices having a photoconductive layer comprising selenium or a selenium alloy, fatigue effects are overcome by irradiation with infrared radiation.