Hole photogeneration in binary solid solutions of triphenylamine and bisphenol-A-polycarbonate

Abstract

By means of potential discharge techniques, the photogeneration of holes has been investigated in solid solutions of triphenylamine and bisphenol‐A‐polycarbonate. The electric field, temperature, and concentration dependences of the quantum efficiency were measured with 300‐nm radiation. The experimental results have been analyzed within the framework of the Onsager theory of geminate recombination. According to this theory, the photogeneration efficiency is determined by the separation distance of the photoexcited electron–hole pair and the quantum yield of pair formation. Depending on the concentration, these values were determined as between 22 and 27 Å and approximately 10−2, respectively. Both are independent of temperature and increase with increasing triphenylamine concentration. From these results, it is concluded that the low intrinsic photogeneration efficiency is due to both the low primary quantum yield and the high recombination probability of the bound electron–hole pair.