Photogeneration action spectroscopy of neutral and charged excitations in films of a ladder-type poly(para-phenylene)

The photogeneration quantum efficiency action spectra of long-lived neutral and charged excitations in films of a ladder-type poly(para-phenylene) wer e measured. We found that both tripler and polaron action spectra show, in addition to a step function increase at the optical gap, a monotonic rise a t higher energies. For triplets this rise is explained by singlet exciton f ission into triplet pairs from which the triplet exciton energy in the gap was obtained; this energy was also confirmed by measuring the weak phosphor escence band. For polarons the photogeneration increase at high energies is modeled by a novel hot electron interchain tunneling process. [S0031-9007( 99)08980-2].