Delocalization Drives Free Charge Generation in Conjugated Polymer Films

doi:10.1021/acsenergylett.8b00108

Title: Delocalization Drives Free Charge Generation in Conjugated Polymer Films

Abstract

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.

Authors:

^[1];

^[1]

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

Publication Date:: 2018-02-19

Research Org.:: National Renewable Energy Lab. (NREL), Golden, CO (United States)

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

OSTI Identifier:: 1426641

Report Number(s):: NREL/JA-5900-70921
Journal ID: ISSN 2380-8195

Grant/Contract Number:: AC36-08GO28308

Resource Type:: Accepted Manuscript

Journal Name:: ACS Energy Letters

Additional Journal Information:: Journal Volume: 3; Journal Issue: 3; Journal ID: ISSN 2380-8195

Publisher:: American Chemical Society (ACS)

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; polymer microstructure; free charge generation; time-resolved microwave conductivity

Citation Formats


                    Pace, Natalie A., Reid, Obadiah G., and Rumbles, Garry. Delocalization Drives Free Charge Generation in Conjugated Polymer Films.  United States: N. p., 2018. 
        Web.  doi:10.1021/acsenergylett.8b00108.

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                    Pace, Natalie A., Reid, Obadiah G., & Rumbles, Garry. Delocalization Drives Free Charge Generation in Conjugated Polymer Films.  United States.  doi:10.1021/acsenergylett.8b00108.

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                    Pace, Natalie A., Reid, Obadiah G., and Rumbles, Garry. Mon .  
        "Delocalization Drives Free Charge Generation in Conjugated Polymer Films".  United States.  doi:10.1021/acsenergylett.8b00108.  https://www.osti.gov/servlets/purl/1426641.

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@article{osti_1426641,

  title        = {Delocalization Drives Free Charge Generation in Conjugated Polymer Films},

  author       = {Pace, Natalie A. and Reid, Obadiah G. and Rumbles, Garry},

  abstractNote = {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.},

  doi          = {10.1021/acsenergylett.8b00108},

  journal      = {ACS Energy Letters},

  number       = 3,

  volume       = 3,

  place        = {United States},

  year         = {2018},

  month        = {2}

}

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Journal Article:

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DOI: 10.1021/acsenergylett.8b00108

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Figures / Tables:

Figure 1: (a) Model System 1: P3DDT and Pc2 structures (b) Model System 2: PFO and C60-4-1 structures (c) Absorption spectrum of the P3DDT/Pc2 sensitized system (d) Absorption spectrum of the PFO/C60-4-1 sensitized system.

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