Publication Date

2016

Journal or Book Title

Nature Communications

Abstract

One of the fundamental design paradigms in organic photovoltaic device engineering is based on the idea that charge separation is an extrinsically driven process requiring an interface for exciton fission. This idea has driven an enormous materials science engineering effort focused on construction of domain sizes commensurate with a nominal exciton diffusion length of order 10 nm. Here, we show that polarized optical excitation of isolated pristine crystalline nanowires of a small molecule n-type organic semiconductor, 7,8,15,16-tetraazaterrylene, generates a significant population of charge-separated polaron pairs along the π-stacking direction. Charge separation was signalled by pronounced power-law photoluminescence decay polarized along the same axis. In the transverse direction, we observed exponential decay associated with excitons localized on individual monomers. We propose that this effect derives from an intrinsic directional charge-transfer interaction that can ultimately be programmed by molecular packing geometry.

DOI

10.1038/ncomms10629

Volume

7

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Funder

Support from the U.S. Department of Energy Grant # DE-FG02-05ER15695 (Program Manager: Larry Rahn) is gratefully acknowledged. N.S.C. and A.L.B. thank the NSF Center for Hierarchical Manufacturing (CMMI-0531171). UMass SOAR Fund

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