School of Chemistry - Research Publications
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ItemA luminescent solar concentrator ray tracing simulator with a graphical user interface: features and applications(IOP PUBLISHING LTD, 2020-07-01)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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ItemEnergy Transfer between CdZnS Quantum Dots and Perylene Diimide Dyes(American Chemical Society, 2023-01-25)QD-dye systems are promising models for artificial photosynthesis and down converter systems for LEDs and displays. To better understand the factors controlling energy transfer from the QDs to the dyes, we fabricated a series of CdxZn1-xS/ZnS quantum dot (QD)-perylene diimide (PDI) composite nanocrystals. The core-shell CdxZn1-xS/ZnS QDs were chosen for better control of surface chemistry and for control of photophysical properties through core composition. The PDIs were designed with bulky substituents to reduce dye-dye aggregation effects. Energy transfer efficiency was found to depend upon both the length of the anchoring alkyl chain and the type of terminal anchoring group. The maximum energy transfer efficiency of 91% from QDs to PDIs was achieved with composites containing PDIs with carboxylic acid anchoring groups and longer alkyl chains. It was found that composites with carboxylic acid anchors exhibited greater photostability than composites with amine anchors. Longer alkyl chains also led to greater photostability. Conversely, shorter chain alkanes promoted faster aggregation of the nanocrystal composites.
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ItemProtection of Boronic Acids Using a Tridentate Aminophenol ONO Ligand for Selective Suzuki-Miyaura Coupling(AMER CHEMICAL SOC, 2023-01-25)Boronic acid protecting group chemistry powerfully enhances the versatility of Suzuki-Miyaura cross-coupling. Prominent examples include trifluoroborate salts, N-methyliminodiacetic acid (MIDA) boronates, and 1,8-diaminonaphthalene boronamides. In this work, we present a bis(2-hydroxybenzyl)methylamine (BOMA) ligand that forms tridentate complexes with boronic acids much like the MIDA ligand but the deprotection is facilitated by organic acids. The BOMA boronates showed considerable stability in both aqueous base and acid, and a variety of chemoselective reactions were performed on these boronates, including selective Suzuki-Miyaura coupling, palladium-catalyzed borylation, ester hydrolysis, alkylation, lithiation-borylation, and oxidative hydroxydeboronation.
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ItemMedium effects on the fluorescence of Imide-substituted naphthalene diimides(Elsevier, 2023-03-01)Naphthalene diimides (NDIs) are a common class of chromophores used in photon harvesting applications due to their functional malleability through substitution of the NDI core. However, some derivatives with substitution at the imide position of the NDI core only become emissive in electron-rich aromatic solvents. This study examines this phenomenon from both an experimental and theoretical perspective, in order to understand how NDIs interact with each other and the surrounding medium upon photoexcitation. We report the photophysical properties of cyclohexyl and several aromatic imide-substituted NDI derivatives, and show that fluorescence properties are strongly influenced by solvation in more electron-rich aromatic solvents (e.g. toluene, xylene, mesitylene). Theoretical modeling supports strong interactions, including ground state charge-transfer complexation, with aromatic solvents. In solid poly(methyl methacrylate) (PMMA) and poly(styrene) (PS) film media, both aggregation and complexation are shown to contribute to absorption and emission properties. The results also demonstrate that aromatic imide substituents not only act to provide steric bulk to the NDI chromophore but participate in interactions with the surrounding medium that affect the overall photophysical properties.
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ItemHarvesting Triplet Excitons in High Mobility Emissive Organic Semiconductor for Efficiency Enhancement of Light-Emitting Transistors(Wiley, 2023-03-29)Organic light-emitting transistors (OLETs), a kind of highly integrated and minimized optoelectronic device, demonstrate great potential applications in various fields. The construction of high-performance OLETs requires the integration of high charge carrier mobility, strong emission, and high triplet exciton utilization efficiency in the active layer. However, it remains a significant long-term challenge, especially for single component active layer OLETs. Herein, the successful harvesting of triplet excitons in a high mobility emissive molecule, 2,6-diphenylanthracene (DPA), through the triplet-triplet annihilation process is demonstrated. By incorporating a highly emissive guest into the DPA host system, an obvious increase in photoluminescence efficiency along with exciton utilization efficiency results in an obvious enhancement of external quantum efficiency of 7.2 times for OLETs compared to the non-doped devices. Moreover, well-tunable multi-color electroluminescence, especially white emission with Commission Internationale del'Eclairage of (0.31, 0.35), from OLETs is also achieved by modulating the doping concentration with a controlled energy transfer process. This work opens a new avenue for integrating strong emission and efficient exciton utilization in high-mobility organic semiconductors for high-performance OLETs and advancing their related functional device applications.
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ItemMeasured power conversion efficiencies of bifacial luminescent solar concentrator photovoltaic devices of the mosaic series(WILEY, 2022-02-28)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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ItemSimulations of Luminescent Solar Concentrator Bifacial Photovoltaic Mosaic Devices Containing Four Different Organic Luminophores(IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2022-02-15)
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ItemLimitations of conjugated polymers as emitters in triplet-triplet annihilation upconversion(ROYAL SOC CHEMISTRY, 2021-10-11)Triplet–triplet annihilation upconversion performances for poly(phenylene-vinylene) emitters were investigated through a series of copolymers with bulky sidechains.
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ItemTetraphenylethene 9,10-Diphenylanthracene Derivatives - Synthesis and Photophysical Properties(WILEY-V C H VERLAG GMBH, 2019-06-01)A series of tetraphenylethene 9,10-diphenylanthracene (TPE-DPA) derivatives have been synthesized, and their photophysical properties studied. Photoluminescence measurements in PMMA, neat films and nanoparticle dispersions reveal that different aggregation states are formed, which leads to different photophysical behavior. The triplet excited state properties were studied using Pt(II) octaethylporphyrin (PtOEP) as triplet sensitizer. Upconverted emission from the DPA moiety is observed in nanoparticle dispersions of each derivative. A higher upconverted emission intensity is observed in aerated (compared to deaerated) solutions of the derivatives following irradiation, which is attributed to oxidation of the TPE moiety. These results provide valuable insight for the design of AIE luminogens for triplet-triplet annihilation upconversion (TTA-UC).