AbstractTemperature dependences of photoreflectance (PR), photoluminescence (PL), and time‐resolved PL have been determined for bulk CuInSe2 single crystals grown by a travelling heater method. The PR spectra exhibited excitonic AB (1.04 eV) and C (1.27 eV) transitions, and their temperature dependence has been determined. PL exhibited an exciton peak at 1.036 eV at 8 K. Other PL peaks at 0.99 eV and 1.01 eV quenched at 40 K and 100 K, respectively. For 50–200 K, exciton PL exhibited thermal quenching with an activation energy (ΔE ) of 16 meV. Further increase in temperature (200 K < T < 300 K) leads to a strong broadening of PL, an abrupt PL energy decrease, and a negative thermal quenching (ΔE = –89 meV). With increase in temperature, the PL lifetime decreases for 80 K < T < 160 K, while it increases for 180 K < T < 300 K. These results suggest a change of the recombination mechanism at about 200 K. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)