Photo-induced electron transfer from a conducting polymer to buckminsterfullerene: A molecular approach to high efficiency photovoltaic cells. Final report

摘要

For photovoltaic cells made with pure conjugated polymers, energy conversion efficiencies were typically 10(sup (minus)3)--10(sup (minus)2)%, too low to be used in practical applications. The recent discovery of photoinduced electron transfer in composites of conducting polymers (as donors) and buckminsterfullerene, C(sub 60), and its derivatives (as acceptors) provided a molecular approach to high efficiency photovoltaic conversion. Since the time scale for photoinduced charge transfer is subpicosecond, more than 10(sup 3) times faster than the radiative or nonradiative decay of photo-excitations, the quantum efficiency for charge transfer and charge separation from donor to acceptor is close to unity. Thus, photoinduced charge transfer across a donor/acceptor (D/A) interface provides an effective method of overcome early time carrier recombination in organic systems and thus to enhance the optoelectronic response of these materials. Progress toward creating bulk D/A heterojunction materials is described by summarizing two publications which resulted from this research, namely: Plastic photovoltaic cells made with donor- acceptor composites -- Enhanced carrier collection efficiency via a network of internal heterojunctions; and Charge separation and photovoltaic conversion in polymer composites with internal donor/acceptor heterojunctions.