Modeling the temperature induced degradation kinetics of the short circuit current in organic bulk heterojunction solar cells

Abstract

In organic bulk heterojunction solar cells, the nanoscale morphology of interpenetrating donor-acceptor materials and the resulting photovoltaic parameters alter as a consequence of prolonged operation at temperatures above the glass transition temperature. Thermal annealing induces clustering of the acceptor material and a corresponding decrease in the short circuit current. A model based on the kinetics of Ostwald ripening is proposed to describe the thermally accelerated degradation of the short circuit current of solar cells with poly(2-methoxy-5-(3', 7'-dimethyloctyloxy)-1,4-phenylenevinylene (MDMO-PPV) as donor and (6,6)-phenyl C-61-butyric acid methyl ester (PCBM) as acceptor. The activation energy for the degradation is determined by an Arrhenius model, allowing to perform shelf life prediction. (C) 2010 American Institute of Physics. [doi:10.1063/1.3391669]