Cooperative Singlet and Triplet Exciton Transport in Tetracene Crystals Visualized by Ultrafast Microscopys

Journal Article · Mon Sep 14 04:00:00 EDT 2015 · Nature Chemistry

DOI:https://doi.org/10.1038/nchem.2348· OSTI ID:1225469

Wan, Yan ^[1]; Guo, Zhi ^[2]; Zhu, Tong ^[1]; Yan, Suxia ^[2]; Johnson, Justin ^[3]; Huang, Libai ^[1]

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1. Purdue Univ., West Lafayette, IN (United States)
2. Univ. of Notre Dame, IN (United States)
3. National Renewable Energy Lab. (NREL), Golden, CO (United States)

Singlet fission presents an attractive solution to overcome the Shockley–Queisser limit by generating two triplet excitons from one singlet exciton. Although triplet excitons are long-lived, their transport occurs through a Dexter transfer, making them slower than singlet excitons, which travel by means of a Förster mechanism. A thorough understanding of the interplay between singlet fission and exciton transport is therefore necessary to assess the potential and challenges of singlet-fission utilization. We report a direct visualization of exciton transport in single tetracene crystals using transient absorption microscopy with 200 fs time resolution and 50 nm spatial precision. Moreover, these measurements reveal a new singlet-mediated transport mechanism for triplets, which leads to an enhancement in effective triplet exciton diffusion of more than one order of magnitude on picosecond to nanosecond timescales. These results establish that there are optimal energetics of singlet and triplet excitons that benefit both singlet fission and exciton diffusion.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1225469
• Report Number(s): NREL/JA--5900-64151
• Journal Information: Nature Chemistry, Journal Name: Nature Chemistry Journal Issue: 10 Vol. 7; ISSN 1755-4330
• Publisher: Nature Publishing Group
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
77 NANOSCIENCE AND NANOTECHNOLOGY
diffusion
photovoltaics
singlet fission
tetracene