Exciton capture by nanocrystals in a polymer matrix

Abstract

A model for the capture of nonequilibrium excitons by semiconductor nanocrystals in a polymer matrix via dipole–dipole interactions is developed. The transition probability W is found by calculating Joule energy losses in the nanocrystal induced by an external oscillating dipole. To find the net capture rate, the problem is solved simultaneously with the diffusion equation describing generation and recombination of excitons in the polymer matrix and their transport to the nanocrystal interface. In real conducting polymers the capture rate is often limited not by dipole interactions but by diffusion transport so that the key condition for high efficiency of light-emitting devices based on organic–inorganic nanocomposites is that the diffusion length of excitons in the polymer matrix exceeds the average internanocrystal spacing.