Förster resonance energy transfer and charge transfer dynamics in ternary organic nanoparticles.

Binary and ternary organic nanoparticles (NPs) comprising 7,7-(4,4-bis(2-Ethylhexyl)-4H-silolo [3,2-b:4,5-b′]dithiophene-2,6-diyl)bis (6-fluoro-4-(5′-hexyl-[2,2′-bithiophen]-5-yl)benzo-[c] [1,2,5]thiadiazole) (p-DTS(FBTTH 2 ) 2 ), poly (3-hexylthiophene) (P3HT) or/and [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) were prepared by precipitation method. The formation of the organic NPs is confirmed by the atomic force microscope (AFM). The absorption spectra show that the blended organic NPs display increased interchain interactions compared to the polymer blends dissolved in the solution. The processes of exciton separation and charge transfer in the organic NPs have been investigated using time-resolved photoluminescence (TRPL) spectroscopy and anisotropy measurements. The results demonstrate that the charge transfer efficiency is improved in the NPs in comparison with that in solution, due to the enhanced interchain interactions and intimate contact between the donor and acceptor materials in NPs. Due to Förster resonance energy transfer (FRET) between P3HT and p-DTS(FBTTH 2 ) 2 , the photodetectors with ternary NPs in the active layers exhibit improved on/off ratios and enhanced detectivity compared with the binary system, demonstrating the promising applications of organic NPs in the ecofriendly fabrication of organic optoelectronic devices. [ABSTRACT FROM AUTHOR]