Study on electron transfer in a heterogeneous system using a density matrix theory approach

Heterogeneous structure of a molecule semiconductor is the essential part of dye-sensitized solar cell, and the charge injection in it is the key factor of efficiency of solar energy conversion. A heterogeneous system is investigated where a metal nano-particle is used to decorate the structure of dye molecules and TiO2 semiconductor. Photoinduced charge injection dynamics from the molecule dye to TiO2 lattice is studied using density matrix theory. Simulations can account for the semiconductor lattice structure, the reflection of electron wave function in the lattice boundary, as well as the plasmon effect of the metal nano-particles. The compound treatment of density matrix theory and wave function approach is verified to be an efficient way for calculating the plasmon effect in the heterogeneous system. It is found that the plasmon enhancement due to the photoexcitation of metal nano-particles can reach as high as 3 orders of magnitude, which is shown to be an efficient way of improvement of charge conversion. The approach of density matrix theory and wave function treatment makes it possible to simulate the charge transfer in large-scale bulk semiconductor, the result of which is helpful for the theoretical analysis of plasmon enhancement in charge transfer dynamics.