Bonn 2025 – scientific programme
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MO: Fachverband Molekülphysik
MO 20: Poster – Molecular Spectroscopy and Dynamics
MO 20.21: Poster
Wednesday, March 12, 2025, 17:00–19:00, Tent
Generation of long-lived triplet-triplet multiexciton in Pentacene-(Tetracene)2-Pentacene intramolecular singlet fission compound - the theoretical perspective. — •Arifa Nazir1, Alok Shukla2, and Sumit Mazumdar3 — 1Indian Institute of Technology Bombay — 2Indian Institute of Technology Bombay — 3University of Arizona
Singlet fission (SF) is a spin-allowed conversion of the optical singlet exciton of an organic semiconductor to the optically dark triplet-triplet 1(T1T1). In chromophores with small triplet-triplet binding energy 1(T1T1) can separate into two free triplets T1, each of which can donate an electron to an acceptor, thereby doubling the photoconductivity of an organic solar cell. Successful implementation of SF requires both ultrafast generation of the 1(T1T1) and rapid dissociation into free triplets, which is a challenge, as the former requires strong coupling between the triplets, which implies strong 1(T1T1) binding energy. Pun et al. synthesized a series of oligomers Pentacene-(Tetracene)n-Pentacene, PTnP, in which rapid generation of pentacene-tetracene triplet-triplet 1(T1[P]T1[T]) is followed by rapid triplet separation to long-lived pentacene-pentacene triplet-triplet 1(T1[P]T1[P]) [1]. We present the results of many-body investigations of the electronic structures of the optical singlet and low-energy triplet-triplets in PT2P that find distinct 1(T1[P]T1[T]) and 1(T1[P]T1[P]). We also report the ground and excited state absorptions that clarify triplet-triplet generation and triplet separation mechanisms. [1] A. B. Pun et al., Nat. Chem. 11, 821 (2019).
Keywords: Singlet Fission; Triplet excitons; organic solar cells