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Title: Dynamics of Singlet Fission and Electron Injection in Self-Assembled Acene Monolayers on Titanium Dioxide

Abstract

We employ a combination of linear spectroscopy, electrochemistry, and transient absorption spectroscopy to characterize the interplay between electron transfer and singlet fission dynamics in polyacene-based dyes attached to nanostructured TiO2. For triisopropyl silylethynyl (TIPS)-pentacene, we find that the singlet fission time constant increases to 6.5 ps on a nanostructured TiO2 surface relative to a thin film time constant of 150 fs, and that triplets do not dissociate after they are formed. In contrast, TIPS-tetracene singlets quickly dissociate in 2 ps at the molecule/TiO2 interface, and this dissociation outcompetes the relatively slow singlet fission process. The addition of an alumina layer slows down electron injection, allowing the formation of triplets from singlet fission in 40 ps. However, the triplets do not inject electrons, which is likely due to a lack of sufficient driving force for triplet dissociation. These results point to the critical balance required between efficient singlet fission and appropriate energetics for interfacial charge transfer.

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1];  [1];  [2];  [2]
  1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
  2. University of Kentucky
Publication Date:
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:
1426639
Report Number(s):
NREL/JA-5900-70661
Journal ID: ISSN 2041-6539
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemical Science (Online); Journal Volume: 9; Journal Issue: 11
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; singlet fission; acene monolayers; titanium dioxide

Citation Formats

Johnson, Justin C, Pace, Natalie A, Arias, Dylan H, Christensen, Steven T, Granger, Devin B., and Anthony, John E. Dynamics of Singlet Fission and Electron Injection in Self-Assembled Acene Monolayers on Titanium Dioxide. United States: N. p., 2018. Web. doi:10.1039/C7SC04688J.
Johnson, Justin C, Pace, Natalie A, Arias, Dylan H, Christensen, Steven T, Granger, Devin B., & Anthony, John E. Dynamics of Singlet Fission and Electron Injection in Self-Assembled Acene Monolayers on Titanium Dioxide. United States. doi:10.1039/C7SC04688J.
Johnson, Justin C, Pace, Natalie A, Arias, Dylan H, Christensen, Steven T, Granger, Devin B., and Anthony, John E. Mon . "Dynamics of Singlet Fission and Electron Injection in Self-Assembled Acene Monolayers on Titanium Dioxide". United States. doi:10.1039/C7SC04688J.
@article{osti_1426639,
title = {Dynamics of Singlet Fission and Electron Injection in Self-Assembled Acene Monolayers on Titanium Dioxide},
author = {Johnson, Justin C and Pace, Natalie A and Arias, Dylan H and Christensen, Steven T and Granger, Devin B. and Anthony, John E.},
abstractNote = {We employ a combination of linear spectroscopy, electrochemistry, and transient absorption spectroscopy to characterize the interplay between electron transfer and singlet fission dynamics in polyacene-based dyes attached to nanostructured TiO2. For triisopropyl silylethynyl (TIPS)-pentacene, we find that the singlet fission time constant increases to 6.5 ps on a nanostructured TiO2 surface relative to a thin film time constant of 150 fs, and that triplets do not dissociate after they are formed. In contrast, TIPS-tetracene singlets quickly dissociate in 2 ps at the molecule/TiO2 interface, and this dissociation outcompetes the relatively slow singlet fission process. The addition of an alumina layer slows down electron injection, allowing the formation of triplets from singlet fission in 40 ps. However, the triplets do not inject electrons, which is likely due to a lack of sufficient driving force for triplet dissociation. These results point to the critical balance required between efficient singlet fission and appropriate energetics for interfacial charge transfer.},
doi = {10.1039/C7SC04688J},
journal = {Chemical Science (Online)},
number = 11,
volume = 9,
place = {United States},
year = {Mon Feb 26 00:00:00 EST 2018},
month = {Mon Feb 26 00:00:00 EST 2018}
}