Reducing non-radiative voltage losses by methylation of push-pull molecular donors in organic solar cells
Résumé
Organic solar cells are approaching power conversion efficiencies of other thin-film technologies. However, in order to become truly market competitive, the still substantial voltage losses need to be reduced. Here, we describe the synthesis and characterization of four novel arylamine-based push-pull molecular donors, two of them exhibiting a methyl group at the para position of the external phenyl ring of the arylamine block. By assessing the charge-transfer state properties and the effects of methylation on the open-circuit voltage of the device, we show that devices based on methylated versions of the molecular donors exhibit reduced voltage losses due to decreased non-radiative recombination. Modelling suggests that methylation results in a tighter interaction between donor and acceptor molecules, turning into a larger oscillator strength to the charge-transfer states, thereby ensuing reduced non-radiative decay rates.
Domaines
Chimie organique| Origine | Fichiers produits par l'(les) auteur(s) |
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