Triplet Harvesting from Intramolecular Singlet Fission in Polytetracene. Issue 41 (14th September 2017)

• Record Type: Journal Article
• Authors: Pun, Andrew B.; Sanders, Samuel N.; Kumarasamy, Elango; Sfeir, Matthew Y.; Congreve, Daniel N.; Campos, Luis M.
• Is Part Of: Advanced materials. Volume 29:Issue 41(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-09-14
• Subjects: organic photovoltaics -- photophysics -- polymer chemistry -- singlet fission; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201701416
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Singlet fission (SF), a promising mechanism of multiple exciton generation, has only recently been engineered as a fast, efficient, intramolecular process (iSF). The challenge now lies in designing and optimizing iSF materials that can be practically applied in high‐performance optoelectronic devices. However, most of the reported iSF systems, such as those based on donor–acceptor polymers or pentacene, have low triplet energies, which limits their applications. Tetracene‐based materials can overcome significant challenges, as the tetracene triplet state is practically useful, ≈1.2 eV. Here, the synthesis and excited state dynamics of a conjugated tetracene homopolymer are studied. This polymer undergoes ultrafast iSF in solution, generating high‐energy triplets on a sub‐picosecond time scale. Magnetic‐field‐dependent photocurrent measurements of polytetracene‐based devices demonstrate the first example of iSF‐generated triplet extraction in devices, exhibiting the potential of iSF materials for use in next‐generation devices. Abstract : A conjugated tetracene homopolymer is synthesized, investigated spectroscopically, and employed as the active layer in photovoltaic devices. Spectroscopic measurements reveal sub‐picosecond singlet fission in this material in solution or in films. Films facilitate dissociation of the resulting triplet pairs. Solution‐processed devices employing polytetracene achieve singlet‐fission‐based photocurrent enhancement, but only when the acceptor energy levels are sufficiently low.