Effect of active layer thickness on the charge recombination and dissociation in bulk heterojunction polymer solar cells under open circuit conditions

Abstract

Bulk heterojunction organic photovoltaic cells (OPVs), which are based on anthracene-containing poly (p-phenylene-ethynylene)-alt-poly (p-phenylene-vinylene) (PPE-PPV) polymer denoted (AnE-PVstat) and phenyl C60 butyric acid methyl ester (PCBM). The active layer thickness was varied from 100 nm to 300 nm. The solar cell parameters and magnetoconductance (MC) effect were analyzed, and the results showed a positive MC effect (+MC) for active layer thicknesses of 100 nm, 150 nm, and 200 nm, while a negative MC effect (-MC) was observed for thicknesses of 250 nm and 300 nm. The Power conversion efficiency (PCE) of 4 ℅ was achieved for an active layer thickness of 200 nm. The triplet-doublet quenching (TQD) model was used to describe the MC effect, which is influenced by triplet-charge reactions on the current based on density matrix formalism using the Stochastic Liouville Equation. The dissociation and recombination rates of the T-D pairs increased with the thickness for thinner layers (100, 150, 200 nm) while decreased for thicker layers (250 nm and 300 nm).