Delocalization Drives Free Charge Generation in Conjugated Polymer Films

Pace, Natalie A.; Reid, Obadiah G.; Rumbles, Garry

doi:10.1021/acsenergylett.8b00108

Delocalization Drives Free Charge Generation in Conjugated Polymer Films

Journal Article · Mon Feb 19 00:00:00 EST 2018 · ACS Energy Letters

DOI:https://doi.org/10.1021/acsenergylett.8b00108· OSTI ID:1426641

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National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Colorado, Boulder, CO (United States)

We demonstrate that the product of photoinduced electron transfer between a conjugated polymer host and a dilute molecular sensitizer is controlled by the structural state of the polymer. Ordered semicrystalline solids exhibit free charge generation, while disordered polymers in the melt phase do not. We use photoluminescence (PL) and time-resolved microwave conductivity (TRMC) measurements to sweep through polymer melt transitions in situ. Free charge generation measured by TRMC turns off upon melting, whereas PL quenching of the molecular sensitizers remains constant, implying unchanged electron transfer efficiency. The key difference is the intermolecular order of the polymer host in the solid state compared to the melt. We propose that this order-disorder transition modulates the localization length of the initial charge-transfer state, which controls the probability of free charge formation.

View Accepted Manuscript (DOE)

Research Organization:: National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

Grant/Contract Number:: AC36-08GO28308

OSTI ID:: 1426641

Report Number(s):: NREL/JA--5900-70921

Journal Information:: ACS Energy Letters, Journal Name: ACS Energy Letters Journal Issue: 3 Vol. 3; ISSN 2380-8195

Publisher:: American Chemical Society (ACS)Copyright Statement

Country of Publication:: United States

Language:: English

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