EXCITON-EXCITON ANNIHILATION AND EXCITON KINETICS IN POLY(DI-N-HEXYLSILANE)

We have found that charge carriers can be generated by exciton-exciton annihilation in solid films of poly(di-n-hexylsilane). We use this phenomenon to study the kinetics of excitons at ambient temperature and show that the rate constant for exciton-exciton annihilation gamma is 2 X 10(-7) cm3 s-1, in excellent agreement with the value we obtained previously by other means. The quantum efficiency for carrier production, at an electric field of 2 X 10(5) V cm-1, is 1. 3 X 10(-3) per annihilation event. We also show that gamma is independent of the initial energy of the exciton state, even to energies far out on the long-wavelength tail of the exciton absorption band, and that the excitons remain mobile throughout their 600-ps lifetime.