New candidates for near-infra-red-absorbing active layers in multijunction organic photovoltaics: Characterization and performance

Dye molecules were modified through exchange of a central nucleofugal functional group. Profound changes in the bandgap spacing and HOMO-LUMO levels were observed. Concentration quenching was observed for all the dyes and increases in external quantum efficiency of devices were observed after dyes were diluted through distribution within a polymer host. The addition of the phenoxy functional group in one derivatized dye appeared to reduce the effect of fluorescence concentration quenching. All characterization herein allows for prediction of the effects of other nucleofugal syntheses on these dyes for more successful application in NIR bulk heterojunction photovoltaics.