Short-circuit current density and spectral response modelling of bulk-heterojunction solar cells

A general model to calculate short circuit current and spectral response of the bulk-heterojunction solar cell is discussed here. In order to get the short circuit current density at each wavelength the generation rate of electron and holes are calculated by the optical modelling based on transfer matrix approach. The drift–diffusion equation is then solved to get the current density at each wavelength using the calculated generation rate. Spectral response is found to be very similar to the experimental data of (3-hexylthiophene) (P3HT): [6,6]-phenyl C61-butyric acid methylester (PCBM) based bulk-heterojunction solar cell. The variation of short circuit current as a function of active layer thickness has been calculated using the model which matches with the experimental observations taken from literature. The sub-linear dependence of short circuit current on incident light intensity has also been explained by the model.