Multiscale description of molecular packing and electronic processes in small-molecule organic solar cells

Abstract

This paper summarizes our recent works on theoretical modelling of molecular packing and electronic processes in small-molecule organic solar cells. Firstly, we used quantum-chemical calculations to illustrate exciton-dissociation and charge-recombination processes at the DTDCTB/C60 interface and particularly emphasized the major role of hot charge-transfer states in the exciton-dissociation processes. Then, we systematically analyzed the influence of DTDCTB surfaces with different features on the vacuum vapor deposition growth and packing morphologies of C60 via atomistic molecular dynamics simulations, and found that the formation of crystalline fullerene is the result of an integrated impact of stability, landscape, and molecular orientation of the substrate surfaces. Also, we investigated the impact of different film-processing conditions, such as solvent evaporation rates and thermal annealing, on molecular packing configurations in a neat small-molecule donor material, DPP(TBFu)2, and discussed the correlation between charge mobility and molecular packing via atomistic simulations in combination with electronic-structure calculations and kinetic Monte Carlo simulations.