Evidence for ultra long range energy transfer in organic photovoltaic donor-acceptor three dimensional films

TL;DR

This paper demonstrates an ultra long range energy transfer in organic photovoltaic layered structures, with a transfer distance of about 100nm, expanding understanding of energy transfer mechanisms and potential device architectures.

Contribution

It provides the first quantitative characterization of long-range energy transfer in P3HT:PCBM films and compares it to existing models, revealing new design possibilities.

Findings

Energy transfer occurs throughout the entire acceptor volume.

Effective transfer range is approximately 100nm.

The mechanism is quantitatively characterized and contrasted with models.

Abstract

We report an ultra long range energy transfer in a layered donor:spacer:acceptor structures, which consist of the typical organic photovoltaic material system of P3HT as the donor and PCBM as the acceptor. By varying the thicknesses of spacer and acceptor layers we show that the energy transfer is to the full volume of the acceptor and not just to its nearest interface, and we find an effective energy transfer range on the order of about 100nm. Our efforts to elucidate the origin of this process, both theoretically and experimentally, are discussed as well. Although it was recently implied that an exceptionally large energy transfer may take place in this material system, this is the first time, to the best of our knowledge, that the energy transfer mechanism is characterized in a quantitative way and compared to the common models. Our analysis offers new prospects for the familiar photovoltaic bi-layer configurations, which may be very efficient if the ultra long range energy transfer is utilized through a suitable architecture.