Aggregate-Induced Self-Assembly and Ultrafast Dynamics of Light-Harvesting D-A-A Polymorphs

Thomas M. Carlino, Qiaoyu Hu, Amy M. Scott

Research output: Contribution to journalArticle

Abstract

Organic dipolar molecules are an emerging class of light harvesters useful in electronic applications and have captured new urgency with the design and synthesis of new molecular structures for device testing. However, research has not evolved beyond the cyclical thin film preparation—device testing—chemical structural modification approach. Without an understanding of polymorphism, molecular photophysics at the interface or metastable morphologies that regulate charge carrier dynamics, it is not obvious a priori if a new molecular structure will produce a suitable thin film morphology for superior device performance without developing structure–function relationships that consider morphology and photophysics. Dipolar, light harvesting molecules are synthesized with a covalent, para-functionalized triphenylamine donor (D) and acceptor (A) in π-conjugated structures, D–A1 and D–A1–A2, that have previously achieved 9.6% power conversion efficiency in thermally evaporated organic solar cell devices with C70. Solution processing and morphological manipulation are hypothesized to reduce ultrafast radiative charge recombination, unique to dipolar structures, that prevents full charge separation to the fullerene. The photophysics of the D–A interface using femtosecond transient absorption spectroscopy is explained, and microscopy data reveal a newly discovered, supramolecular amorphous polymer metastable state presented as a transient absorption assisted strategy for photofunctional polymorph design.

Original languageEnglish (US)
Article number1800391
JournalMacromolecular Rapid Communications
Volume39
Issue number18
DOIs
StatePublished - Sep 1 2018

Fingerprint

Polymorphism
Self assembly
Molecular structure
Fullerenes
Thin films
Molecules
Harvesters
Charge carriers
Absorption spectroscopy
Conversion efficiency
Microscopic examination
Polymers
Testing
Processing

Keywords

  • benzothiadiazole
  • morphology
  • organic thin films
  • photoinduced charge recombination
  • polymorphism
  • spherulites
  • time-resolved spectroscopy

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

Cite this

Aggregate-Induced Self-Assembly and Ultrafast Dynamics of Light-Harvesting D-A-A Polymorphs. / Carlino, Thomas M.; Hu, Qiaoyu; Scott, Amy M.

In: Macromolecular Rapid Communications, Vol. 39, No. 18, 1800391, 01.09.2018.

Research output: Contribution to journalArticle

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