Energy transfer and selective hole injection in blended conjugated polymer nanoparticles

CHANG, YA-LAN; CHANG, WEI-SHUN; FAN, FU-REN F.; PALACIOS, RODRIGO E.; BARD, ALLEN J.; BARBARA, PAUL F.

New Orleans, LA, EE.UU

Congreso; The 235th ACS National Meeting; 2008

The American Chemical Society

Energy transfer and selective hole injection in polymer nanoparticles composed of F8BT (donor) doped with single polymer chain BEH-PPV (acceptor) was studied with the new electrochemical single molecule spectroscopy (EC-SMS) technique. In particles containing 1% BEHPPV, the acceptor component showed fluorescence intermittency suggesting that single chain doping levels were achieved at this concentration. Assuming an average nanoparticle diameter of 25nm, we estimated a Förster radius of 5.4nm via the fraction of acceptor fluorescence of 13% for 1% blend nanoparticle. Selective hole injection to the acceptor was observed where holes are localized on BEHPPV chains. A symmetric and reversible fluorescence-intensity modulation of the 1% blend nanoparticles with an applied pulse bias of 0.9V suggests that the injected holes do not become deeply trapped. This result suggests multi-chain of the same polymer is required to cause the relaxation of chemical structure, which is a possible source of deep traps.