Specific features of photoluminescence and nanosecond relaxation of photocurrent in CuIn$_{5}$S$_{8}$ crystals upon strong optical excitation

Intense luminescence and nanosecond relaxation of photocurrent upon strong optical excitation have been observed in CuIn$_{5}$S$_{8}$ crystals grown by slow melt cooling at a constant temperature gradient. Three emission bands with energies of 1.52, 1.48, and 1.465 eV are distinguished in the photoluminescence spectra. The crystal photoactivation in the range of 300–600 K is explained by an increase in the hole mobility in the valence band with an increase in temperature.