Competition between recombination and extraction of free charges determines the fill factor of organic solar cells.

ABSTRACT: Among the parameters that characterize a solar cell and define its power-conversion efficiency, the fill factor is the least well understood, making targeted improvements difficult. Here we quantify the competition between charge extraction and recombination by using a single parameter θ, and we demonstrate that this parameter is directly related to the fill factor of many different bulk-heterojunction solar cells. Our finding is supported by experimental measurements on 15 different donor:acceptor combinations, as well as by drift-diffusion simulations of organic solar cells in which charge-carrier mobilities, recombination rate, light intensity, energy levels and active-layer thickness are all varied over wide ranges to reproduce typical experimental conditions. The results unify the fil

SUBMITTER: Bartesaghi D 

PROVIDER: S-EPMC4432638 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature