School of Chemistry - Research Publications

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Author: White, Jonathan × Author: Ghiggino, Kenneth × Author: Smith, Trevor ×

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    The role of conformational heterogeneity in the excited state dynamics of linked diketopyrrolopyrrole dimers†
    Bradley, SJ ; Chi, M ; White, JM ; Hall, CR ; Goerigk, L ; Smith, TA ; Ghiggino, KP (ROYAL SOC CHEMISTRY, 2021-04-21)
    Diketopyrrolopyrrole (DPP) derivatives have been proposed for both singlet fission and energy upconversion as they meet the energetic requirements and exhibit superior photostability compared to many other chromophores. In this study, both time-resolved electronic and IR spectroscopy have been applied to investigate excited state relaxation processes competing with fission in dimers of DPP derivatives with varying linker structures. A charge-separated (CS) state is shown to be an important intermediate with dynamics that are both solvent and linker dependent. The CS state is found for a subset of the total population of excited molecules and it is proposed that CS state formation requires suitably aligned dimers within a broader distribution of conformations available in solution. No long-lived triplet signatures indicative of singlet fission were detected, with the CS state likely acting as an alternative relaxation pathway for the excitation energy. This study provides insight into the role of molecular conformation in determining excited state relaxation pathways in DPP dimer systems.
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    Energy Migration in Organic Solar Concentrators with a Molecularly Insulated Perylene Diimide
    Banal, JL ; Soleimaninejad, H ; Jradi, FM ; Liu, M ; White, JM ; Blakers, AW ; Cooper, MW ; Jones, DJ ; Ghiggino, KP ; Marder, SR ; Smith, TA ; Wong, WWH (AMER CHEMICAL SOC, 2016-06-23)
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    Highly Fluorescent Molecularly Insulated Perylene Diimides: Effect of Concentration on Photophysical Properties
    Zhang, B ; Soleimaninejad, H ; Jones, DJ ; White, JM ; Ghiggino, KP ; Smith, TA ; Wong, WWH (AMER CHEMICAL SOC, 2017-10-10)
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    Exciton Dynamics of Photoexcited Pendant Porphyrin Polymers in Solution and in Thin Films
    Stevens, AL ; Novakovic, S ; White, JM ; Wong, WWH ; Smith, TA ; Ghiggino, KP ; Paige, MF ; Steer, RP (American Chemical Society, 2018-12-20)
    Several new polymers with rotatable zinc porphyrin pendants have been synthesized and their optical spectroscopic and photophysical properties, including upconversion efficiencies, determined in both fluid solution and thin films. Comparisons made with the β-substituted zinc tetraphenylporphyrin monomers and ZnTPP itself reveal that the yield of triplets resulting from either Q-band or Soret-band excitation of the polymers is surprisingly small. A detailed kinetic analysis of the fluorescence decays and transient triplet absorptions of the substituted monomers and their corresponding polymers reveals that this phenomenon is due to two parallel internal singlet quenching processes assigned to transient intrachain excimer formation. Consequently, the yields of upconverted S2 fluorescence resulting from Q-band excitation in the degassed polymers are significantly diminished in both fluid solution and thin films. Implications of these results for the design of polymer upconverting systems are discussed.