ABSTRACT
Cherkasov et al. (1980) measured photogeneration efficiencies in PVK:TNF charge-transfer complexes. The results show an increase in efficiency as the excitation time decreases. The same phenomenon was later described by Gaidelis et al. (1984). The results were explained by an argument due to Boon (1972) and Akimov et al. (1980). According to the argument, the increase in efficiency is a result of an increase in the photoexcitation density and occurs in materials where the primary event consists of the formation of a bound electron-hole pair. As the pair density increases, the distance between pairs decreases. This leads to a dipole dipole interaction, which results in a decrease in the Coulomb energy of the bound pair and a subsequent increase in the photogeneration efficiency. Cherkasov and Aleksandrova (1990) later argued that the dipole-dipole interaction energy depends on the concentration of complexes and the dispersion in pair separation distances.
