The solvent effect usually plays an important role in triplet-triplet annihilation (TTA) upconversion processes. In this work, we have studied the TTA upconversion kinetics of perylene with Bodipy-phenyl-C60 as the triplet photosensitizer in five solvents, 1,4-dioxane, dichlorobenzene, chlorobenzene, toluene, and tetrahydrofuran (THF). Although no significant solvent effect was observed in steady-state absorption and fluorescence emission spectra, the overall TTA upconversion quantum yields showed a profound dependence on solvent properties, i.e. 4.9% in 1,4-dioxane, 7.1% in dichlorobenzene, 6.7% in chlorobenzene, 4.6% in toluene, and 2.2% in THF (the maximum of 50%). Each elementary reaction step involved in the overall process was analyzed by applying femtosecond and nanosecond time-resolved transient absorption spectroscopy, revealing that the fluorescence emission of perylene was more significantly affected by the solvents in contrast to the other steps. Moreover, an extra intramolecular energy-transfer pathway of Bodipy-phenyl-C60 was found via the formation of charge-separated states in dichlorobenzene, chlorobenzene, and THF solvents, once being excited. These conclusions provide valuable clues to choose the most favorable solvent for the higher TTA upconversion efficiency in related applications.
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http://dx.doi.org/10.1039/d0cp04230g | DOI Listing |
Mater Adv
January 2025
Department of Materials Science and Metallurgy, University of Cambridge CB3 0FS UK
The ability to convert light to higher energies through triplet-triplet annihilation upconversion (TTA-UC) is attractive for a range of applications including solar energy harvesting, bioimaging and anti-counterfeiting. Practical applications require integration of the TTA-UC chromophores within a suitable host, which leads to a compromise between the high upconversion efficiencies achievable in liquids and the durability of solids. Herein, we present a series of methacrylate copolymers as TTA-UC hosts, in which the glass transition temperature ( ), and hence upconversion efficiency can be tuned by varying the co-monomer ratios (-hexyl methacrylate (HMA) and 2,2,2-trifluoroethyl methacrylate (TFEMA)).
View Article and Find Full Text PDFChem Sci
January 2025
University of Gothenburg, Department of Chemistry and Molecular Biology Medicinaregatan 7B 41390 Gothenburg Sweden
Triplet-triplet annihilation photon upconversion (TTA-UC) combines the energy of two photons to provide one of higher energy that can be used to drive photochemical or photophysical processes. TTA-UC proceeds at high efficiencies in dilute solution, but in solid state the efficiency drastically reduces. This is because exciton diffusion, compared to molecular diffusion in solid annihilator films, suffers concentration induced quenching, undermining efficient emission.
View Article and Find Full Text PDFJ Mater Chem C Mater
December 2024
Department of Materials Science and Metallurgy, University of Cambridge 27 Charles Babbage Road Cambridge CB3 0FS UK
Photoswitchable materials are of significant interest for diverse applications from energy and data storage to additive manufacturing and soft robotics. However, the absorption profile is often a limiting factor for practical applications. This can be overcome using indirect excitation complementary photophysical pathways, such as triplet sensitisation or photon upconversion.
View Article and Find Full Text PDFBiomater Res
November 2024
School of Chemical Engineering and Institute for Advanced Organic Materials, Pusan National University, Busan 46241, Republic of Korea.
Photomedicine, which utilizes light for therapeutic purposes, has several hurdles such as limited tissue penetration for short-wavelength light and inadequate deep tissue efficacy for long-wavelength light. Photon energy upconversion (UC) reveals promise in photomedicine because it enables the conversion of lower-energy photons into higher-energy photon. Lanthanide (Ln)-based inorganic UC system has been extensively studied but faces challenges, including high excitation laser power density, intrinsically subpar UC quantum efficiency, and potential biotoxicity.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
State Key Laboratory of Extreme Photonics and Instrumentation, Zhejiang Key Laboratory of Excited-State Energy Conversion and Energy Storage, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
Solid state photon upconversion by triplet-triplet annihilation (TTA), particularly near-infrared (NIR)-to-blue upconversion, holds instant promise for enhancing optoelectronic and photochemical applications. Despite extensive studies, NIR-to-blue upconversion has remained particularly challenging and elusive due to inherent multiple energy-downhill processes in TTA upconversion. In this study, using atomically thin two dimensional (2D) monolayer semiconductor as a triplet sensitizer, we demonstrate an efficient and robust solid-state NIR-to-blue photon upconversion system.
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