A two-scale method for fast estimation of the charge-carrier diffusion coefficient in nano-porous semi-conductors

Current numerical methods that simultaneously take into account both spatial and energy disorders in charge-carrier transport in semi-conductor nano-porous structures are exact but involve intensive computations. Here, we will describe a two-scale simulation approach that incorporates all the relevant data on the morphology as well as the microscopic transport model. To test this method, we carried out extensive computer simulations for estimation of the charge-carrier diffusion coefficient in structures of different local and global morphologies. Excellent agreement was found between the results of our proposed model and the results emerged from full-scale calculations. The speed-up in the computations is almost four orders of magnitude. As such, this method provides us with a fast and straightforward approach to separate the role of local and global morphology on the charge-carrier transport and hence might be helpful in future designing of devices like dye-sensitized solar cells.