Abstract
Temporal decay of delayed luminescence (DL) of PVK excited by 4.02 eV photons of an excimer laser has been studied in the time domain 10 μs to 20 s at 297 K and 80 K, respectively, and at selected emission wavelengths (388 nm, 418 nm, 500 nm). At 297 K, DL is controlled by the recombination of geminately bound electron-hole pairs because under the high excitation doses employed, triplet-triplet annihilation occurs on a faster time scale. At 80 K fusion among localized triplet states contributes to DL as well. In combination with literature data for different systems studied in the time domain 10 s to 104 s the present results confirm that geminate pair recombination in disordered organic solids obeys a hyperbolic decay law in accord with the predictions of both Monte Carlo simulation and localization theory for systems with built-in energetic disorder.