Delayed luminescence in a molecularly doped polymer (TAPC in polycarbonate)

Abstract

AbstractDecay of the delayed luminescence of 1,1‐bis(di‐4‐tolylaminophenyl)cyclohexane, both doped into a polycarbonate binder and matrix‐isolated in an MTHF glass, has been studied upon excitation with the 308 nm line of an excimer laser. Time‐resolved emission spectra have also been recorded. In the early time regime, 30 ns < t < 10 μs, the decay of the emission, identified as delayed fluorescence rather than phosphorescence, follows a power‐law characteristic of geminate pair recombination in a disordered medium. Singlet–singlet excitation fusion is considered to be the main pathway for geminate pair formation. Fusion of triplet excitations becomes important for e–h pair formation at long times only (10 μs < t < 10 ms). The rate of triplet–triplet encounters carries a time dependence characteristic of the random walk of excitations in a disordered solid.