SUBPICOSECOND PHOTOINDUCED ELECTRON-TRANSFER FROM CONJUGATED POLYMERSTO FUNCTIONALIZED FULLERENES

We report time-resolved excited state absorption measurements which de monstrate subpicosecond photoinduced electron transfer using soluble d erivatives of poly(p-phenylene vinylene) as donors blended with a func tionalized fullerene (methanofullerene) as acceptor. The subpicosecond photoinduced absorption spectra of the polymer/methanofullerene blend s show that electron transfer from the donor to the acceptor occurs wi thin a picosecond of photoexcitation of the conjugated polymer. Precis e determination of the electron transfer dynamics was obtained by moni toring the dichroic ratio. The charge separated state is metastable an d persists into the millisecond time domain, yielding an asymmetry of 10 orders of magnitude between the forward and reverse electron transf er times. The increased miscibility of the functionalized methanofulle rene with the conjugated polymer is important for preparation of films with sufficiently high acceptor concentrations for practical devices based on photoinduced charge separation. (C) 1996 American Institute o f Physics.