School of Chemistry - Research Publications

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    A luminescent solar concentrator ray tracing simulator with a graphical user interface: features and applications
    Zhang, B ; Yang, H ; Warner, T ; Mulvaney, P ; Rosengarten, G ; Wong, WWH ; Ghiggino, KP (IOP PUBLISHING LTD, 2020-07)
    A Monte-Carlo ray tracing simulator with a graphical user interface (MCRTS-GUI) has been developed to provide a quantitative description, performance evaluation and photon loss analysis of luminescent solar concentrators (LSCs). The algorithm is applied to several practical LSC device structures including multiple dyes in the same waveguiding layer, and structures where a dye layer is sandwiched between clear substrates. The effect of the host matrix absorption and the influence of the neighboring layers are investigated. Validations demonstrate that the MCRTS-GUI developed provides a reliable and accurate description of LSC performance. Code for the mixed-dye single layer configuration is converted into a ray-tracing package with a user-friendly interface and is made available as open source software.
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    Consensus statement: Standardized reporting of power-producing luminescent solar concentrator performance
    Yang, C ; Atwater, HA ; Baldo, MA ; Baran, D ; Barile, CJ ; Barr, MC ; Bates, M ; Bawendi, MG ; Bergren, MR ; Borhan, B ; Brabec, CJ ; Brovelli, S ; Bulovic, V ; Ceroni, P ; Debije, MG ; Delgado-Sanchez, J-M ; Dong, W-J ; Duxbury, PM ; Evans, RC ; Forrest, SR ; Gamelin, DR ; Giebink, NC ; Gong, X ; Griffini, G ; Guo, F ; Herrera, CK ; Ho-Baillie, AWY ; Holmes, RJ ; Hong, S-K ; Kirchartz, T ; Levine, BG ; Li, H ; Li, Y ; Liu, D ; Loi, MA ; Luscombe, CK ; Makarov, NS ; Mateen, F ; Mazzaro, R ; McDaniel, H ; McGehee, MD ; Meinardi, F ; Menendez-Velazquez, A ; Min, J ; Mitzi, DB ; Moemeni, M ; Moon, JH ; Nattestad, A ; Nazeeruddin, MK ; Nogueira, AF ; Paetzold, UW ; Patrick, DL ; Pucci, A ; Rand, BP ; Reichmanis, E ; Richards, BS ; Roncali, J ; Rosei, F ; Schmidt, TW ; So, F ; Tu, C-C ; Vahdani, A ; van Sark, WGJHM ; Verduzco, R ; Vomiero, A ; Wong, WWH ; Wu, K ; Yip, H-L ; Zhang, X ; Zhao, H ; Lunt, RR (CELL PRESS, 2022-01-19)
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    Measured power conversion efficiencies of bifacial luminescent solar concentrator photovoltaic devices of the mosaic series
    Aghaei, M ; Pelosi, R ; Wong, WWH ; Schmidt, T ; Debije, MG ; Reinders, AHME (WILEY, 2022-07)
    Abstract The optical and electrical performances of varied configurations of visually attractive mosaic cubical luminescent solar concentrator photovoltaic (LSC PV) devices have been measured. These new designs of LSC PV devices consist of four cubical lightguides containing commercially available fluorophores with edge‐ and bottom‐mounted silicon solar cells. The 1 cm3 cubical component LSC PVs are made of poly (methyl methacrylate) (PMMA) doped by dyes from 10 to 150 ppm. The lightguides are covered with bifacial silicon solar cells at their edges and/or bottom and connected in series or parallel, depending on the device configuration. In total, 19 different configurations of mosaic LSC PV devices have been experimentally evaluated in this study.
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    Simulations of Luminescent Solar Concentrator Bifacial Photovoltaic Mosaic Devices Containing Four Different Organic Luminophores
    Aghaei, M ; Zhu, X ; Debije, M ; Wong, W ; Schmidt, T ; Reinders, A (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022-05)
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    Limitations of conjugated polymers as emitters in triplet-triplet annihilation upconversion
    O'shea, R ; Gao, C ; Bradley, S ; Owyong, TC ; Wu, N ; White, JM ; Ghiggino, KP ; Wong, WWH (ROYAL SOC CHEMISTRY, 2021-11-29)
    Triplet–triplet annihilation upconversion performances for poly(phenylene-vinylene) emitters were investigated through a series of copolymers with bulky sidechains.
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    Revealing the influence of steric bulk on the triplet-triplet annihilation upconversion performance of conjugated polymers
    O'shea, R ; Kendrick, WJ ; Gao, C ; Owyong, TC ; White, JM ; Ghiggino, KP ; Wong, WWH (NATURE PORTFOLIO, 2021-10-01)
    A series of poly(phenylene-vinylene)-based copolymers are synthesized using the Gilch method incorporating monomers with sterically bulky sidechains. The photochemical upconversion performance of these polymers as emitters are investigated using a palladium tetraphenyltetrabenzoporphyrin triplet sensitizer and MEH-PPV as reference. Increased incorporation of sterically bulky monomers leads to a reduction in the upconversion efficiency despite improved photoluminescence quantum yield. A phosphorescence quenching study indicates issues with the energy transfer process between the triplet sensitizer and the copolymers. The best performance with 0.18% upconversion quantum yield is obtained for the copolymer containing 10% monomer with bulky sidechains.
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    Molecular doped organic semiconductor crystals for optoelectronic device applications
    Qin, Z ; Gao, C ; Wong, WWH ; Riede, MK ; Wang, T ; Dong, H ; Zhen, Y ; Hu, W (Royal Society of Chemistry, 2020-11-21)
    For semiconductors, doping is an efficient approach to tune their energy bandgaps, charge transport, and optical properties which could enable the improvement of the corresponding performances and open up the possibility of multifunction integration. Recently, significant advances have been achieved in molecular doped organic semiconductors, especially doped organic semiconductor single crystals (OSSCs) which have features of well-defined packing structures, long-range molecular orders, and low-density defects for fundamental studies and improved properties. In this review, we will give a summary of the exciting progress of molecular doped OSSCs from the aspects of selection criteria of molecular dopants, general growth methods, and resulting optoelectronic properties as well as their applications in optoelectronic devices. Finally, a brief conclusion is given with challenges and perspectives of molecular doped OSSCs and their related promising research directions in this field.
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    Optimising molecular rotors to AIE fluorophores for mitochondria uptake and retention
    OwYong, TC ; Ding, S ; Wu, N ; Fellowes, T ; Chen, S ; White, JM ; Wong, WWH ; Hong, Y (ROYAL SOC CHEMISTRY, 2020-12-07)
    Molecular rotors exhibit fluorescence enhancement in a confined environment and thus have been used extensively in biological imaging. However, many molecular rotors suffer from small Stokes shift and self-aggregation caused quenching. In this work, we have synthesised a series of red emissive molecular rotors based on cationic α-cyanostilbene. Profoundly enhanced aggregation-induced emission (AIE) properties and greatly widened Stokes shifts can be achieved by molecular engineering. With specificity to stain mitochondria, we demonstrate a simple approach to achieve cell uptake and retention upon tuning the pyridinium substituent of the dyes.
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    Detection of Halomethanes Using Cesium Lead Halide Perovskite Nanocrystals
    Yin, W ; Li, H ; Chesman, ASR ; Tadgell, B ; Scully, AD ; Wang, M ; Huang, W ; McNeill, CR ; Wong, WWH ; Medhekar, N ; Mulvaney, P ; Jasieniak, JJ (AMER CHEMICAL SOC, 2021-01-26)
    The extensive use of halomethanes (CH3X, X = F, Cl, Br, I) as refrigerants, propellants, and pesticides has drawn serious concern due to their adverse biological and atmospheric impact. However, there are currently no portable rapid and accurate monitoring systems for their detection. This work introduces an approach for the selective and sensitive detection of halomethanes using photoluminescence spectral shifts in cesium lead halide perovskite nanocrystals. Focusing on iodomethane (CH3I) as a model system, it is shown that cesium lead bromide (CsPbBr3) nanocrystals can undergo rapid (<5 s) halide exchange, but only after exposure to oleylamine to induce nucleophilic substitution of the CH3I and release the iodide species. The extent of the halide exchange is directly dependent on the CH3I concentration, with the photoluminescence emission of the CsPbBr3 nanocrystals exhibiting a redshift of more than 150 nm upon the addition of 10 ppmv of CH3I. This represents the widest detection range and the highest sensitivity to the detection of halomethanes using a low-cost and portable approach reported to date. Furthermore, inherent selectivity for halomethanes compared to other organohalide analogues is achieved through the dramatic differences in their alkylation reactivity.
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    Pyridine End-Capped Polymer to Stabilize Organic Nanoparticle Dispersions for Solar Cell Fabrication through Reversible Pyridinium Salt Formation
    Saxena, S ; Marlow, P ; Subbiah, J ; Colsmann, A ; Wong, WWH ; Jones, DJ (AMER CHEMICAL SOC, 2021-08-04)
    Bulk-heterojunction nanoparticle dispersions in water or alcohol can be employed as eco-friendly inks for the fabrication of organic solar cells by printing or coating. However, one major drawback is the need for stabilizing surfactants, which facilitate nanoparticle formation but later hamper device performance. When surfactant-free dispersions are formulated, a strong limitation is imposed by the dispersion concentration due to the tendency of nanoparticles to aggregate. In this work, pyridine end-capped poly(3-hexylthiophene) (P3HT-Py) is synthesized and included as an additive for the stabilization of P3HT:indene-C60 bis-adduct (ICBA) nanoparticle dispersions. In the presence of acetic acid (AcOH), a surface-active pyridinium acetate end-capped P3HT ion pair, P3HT-PyH+AcO-, is formed which effectively stabilizes the dispersion and hence allows the formation of dispersions with smaller nanoparticle sizes and higher concentrations of up to 30 mg/mL in methanol. The dispersions exhibit an enhanced shelf-lifetime of at least 60 days at room temperature. After the deposition of light-harvesting layers from the nanoparticle dispersions, the ion-pair formation is reversed at elevated temperatures leading to regeneration of P3HT-Py and AcOH. The AcOH evaporates from the active layer, while the performance of the corresponding solar cells is not affected by the residual P3HT-Py in the devices. Enhanced nanoparticle stability is achieved with only 0.017 wt % pyridine in the P3HT/ICBA formulation.