Temperature Dependence of Electroluminescence

Electroluminescent brightness measurements were carried out on several zinc sulfide phosphors over wide ranges of temperature and frequency. From the temperature dependence of photoluminescence a thermal extinction factor was derived which, when introduced in the electroluminescent brightness values, led to an ideal electroluminescent brightness unaffected by thermal quenching. In general, this ideal brightness was found to increase or tend to saturation with increasing temperature, but did not decrease. The temperature sensitivity of the ideal electroluminescence is explained on the basis of a two‐step mechanism: the excitation process and the return process. Luminescence is assumed to occur only during the latter process. On the phosphors studied the temperature dependence of the ideal electroluminescent brightness seems to be due mainly to the thermal behavior of traps during the return process, since the electron return is impeded by traps.