Geminate Pair Recombination in Polyvinylcarbazole

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.