School of Chemistry - Research Publications

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Author: White, Jonathan × Author: Ghiggino, Kenneth × Author: Smith, Trevor × Start date: 2016 × End date: 2019 ×

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    Highly Efficient Luminescent Solar Concentrators by Selective Alignment of Donor-Emitter Fluorophores
    Zhang, B ; Gao, C ; Soleimaninejad, H ; White, JM ; Smith, TA ; Jones, DJ ; Ghiggino, KP ; Wong, WWH (AMER CHEMICAL SOC, 2019-04-23)
    Vertically aligning fluorophores to the surface of a waveguide is known to be an effective approach to improve the optical quantum efficiency (OQE) of luminescent solar concentrators (LSCs). While the chromophore alignment assists waveguiding of the emitted photons to the LSC edges, it also significantly reduces the light-harvesting properties of the LSC. We report here a fluorophore pair consisting of a sphere-shaped energy donor and a rod-shaped emitter that was incorporated in LSCs to provide selective fluorophore alignment to address the reduced incident-light absorption issue. A liquid-crystal polymer matrix was used to perpendicularly align the rod-shaped acceptors to a favorable orientation for light guiding, while the sphere-shaped donor was randomly oriented to maintain its light-absorbing properties. The OQE of LSC devices with this selectively aligned donor-acceptor fluorophore system is 78% without significant loss of light-harvesting capability.
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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.