title: Synthesis and Exciton Dynamics of Triplet Sensitized Conjugated Polymers.
abstract: We report the synthesis of a novel polythiophene-based host-guest copolymer incorporating a Pt-porphyrin complex (TTP-Pt) into the backbone for efficient singlet to triplet polymer exciton sensitization. We elucidated the exciton dynamics in thin films of the material by means of Transient Absorption Spectrosopcy (TAS) on multiple time scales and investigated the mechanism of triplet exciton formation. During sensitization, singlet exciton diffusion is followed by exciton transfer from the polymer backbone to the complex where it undergoes intersystem crossing to the triplet state of the complex. We directly monitored the triplet exciton back transfer from the Pt-porphyrin to the polymer and found that 60% of the complex triplet excitons were transferred with a time constant of 1087 ps. We propose an equilibrium between polymer and porphyrin triplet states as a result of the low triplet diffusion length in the polymer backbone and hence an increased local triplet population resulting in increased triplet-triplet annihilation. This novel system has significant implications for the design of novel materials for triplet sensitized solar cells and upconversion layers.
authors.affiliation: †Centre for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ.
authors.forename: Rolf
authors.initials: R
authors.lastname: Andernach
authors.affiliation: †Centre for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ.|‡Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Utzat
authors.affiliation: †Centre for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ.
authors.forename: Stoichko D
authors.initials: SD
authors.lastname: Dimitrov
authors.affiliation: †Centre for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ.|§SPERC, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
authors.forename: Iain
authors.initials: I
authors.lastname: McCulloch
authors.affiliation: †Centre for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ.
authors.forename: Martin
authors.initials: M
authors.lastname: Heeney
authors.affiliation: †Centre for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ.
authors.forename: James R
authors.initials: JR
authors.lastname: Durrant
authors.affiliation: ∥Department of Chemistry, University College London, London, United Kingdom WC1H 0AJ.
authors.forename: Hugo
authors.initials: H
authors.lastname: Bronstein