title: The Ultrafast Singlet Fission Dynamics in Solution and Thin Film
creator: Wollscheid, Nikolaus
subject: ddc-500
subject: 500 Natural sciences and mathematics
description: Singlet fission (SF) is a process where two triplet charge-carriers are generated from one photoexcited singlet state. This opens up the possibility to increase the efficiency limit for single-junction solar cells by one third from 33% to 44%. In this work, the long-lasting question of the effect of competing pathways on the efficiency of SF is addressed by time-resolved spectroscopy and a novel global fit approach. This is demonstrated on two examples. First, SF is established in a new class of molecules, the tetraazaperopyrenes. Here, substituent-dependent factors, namely excimer formation as well as vibronic and spin-orbit coupling, are identified to be decisive for SF efficiency. Subsequently, solutions of (hetero-) acenes are investigated, in which comparisons between ambient conditions and deaerated solutions highlight the importance of molecular oxygen for SF: A new, sequential mechanism including atmospheric oxygen as a catalyst is resolved, which allows for a step-wise doubling of triplet states even at low chromophore concentrations. In concentrated solutions, diffusion-controlled SF outcompetes other reaction pathways resulting in triplet yields close to 200%. The absence of any intermediate species emphasises the efficiency of this process.
date: 2021
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/29431/1/Dissertation_Nikolaus_Wollscheid.pdf
identifier: DOI:10.11588/heidok.00029431
identifier: urn:nbn:de:bsz:16-heidok-294317
identifier:   Wollscheid, Nikolaus  (2021) The Ultrafast Singlet Fission Dynamics in Solution and Thin Film.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/29431/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng