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Triplet‐Triplet Annihilation Upconversion in a MOF with Acceptor‐filled Channels
摘要： Photon upconversion enjoys an increasing interest in the last years due to its high potential for solar energy harvesting and in bio-imaging. A challenge for triplet-triplet annihilation upconversion (TTA-UC) processes is to realize these features in solid materials without undesired phase segregation and detrimental dye aggregation. To achieve this, we combine a palladium porphyrin sensitizer and a 9,10-diphenylanthracene annihilator within a crystalline mesoporous metal-organic framework using an inverted design. In this modular TTA system, the framework walls constitute the fixed sensitizer, while caprylic acid coats the channels providing a solvent-like environment for the mobile annihilator in the channel. The resulting solid material shows green-to-blue delayed upconverted emission with a luminescence lifetime of 373±5 μs, a threshold value of 329 mW cm–2 and a triplet-triplet energy transfer efficiency of 82%. The versatile design allows straightforward changing the acceptor amount and type.
关键词： triplet-triplet annihilation,porphyrins,metal-organic frameworks,upconversion,hybrid materials
更新于2025-09-11 14:15:04
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Precise Control of Localized Surface Plasmon Wavelengths Is Needed for Effective Enhancement of Triplet-Triplet Annihilation-Based Upconversion Emission
摘要： In this study, we demonstrate that the localized surface plasmon (LSP) resonance of metal nanoparticles, depending strictly on the generating wavelength of LSP resonance, can have both beneficial enhancement and harmful quenching effects on a triplet-triplet annihilation-based upconversion (TTA-UC) emission. When the LSP resonance band of anisotropic silver nanoprisms spectrally overlapped with the photoexcitation wavelength of a sensitizer and the fluorescence of an emitter, an increase in the photoexcitation efficiency and an acceleration of the radiative decay rate were respectively induced, resulting in an effective enhancement in the TTA-UC emission. Furthermore, the overlapping with the photoexcitation wavelength led to a significant decrease (93%) in the threshold light excitation intensity, which greatly enhances the figure-of-merit in TTA-UC systems. However, when the LSP resonance band overlapped with the phosphorescence band of the sensitizer, the TTA-UC emission was extremely quenched, accompanied by the enhanced phosphorescence and the decreased phosphorescence lifetime. These results suggest that the decrease in the TTA-UC emission is a result of the competition between the triplet-triplet energy transfer to the emitter and the LSP-induced nonradiative energy transfer to the silver nanoprisms from the triplet-excited sensitizer. This discovery of the conflicting effects of LSP resonance provides an important guideline: a precise adjustment of LSP resonance wavelengths is needed for the efficient enhancement of TTA-UC emission. This requirement is different from those of other fluorescence systems such as single downconverted fluorophores and lanthanide-based upconversion nanoparticles.
关键词： solid state,fluorescence,phosphorescence,silver nanoprisms,localized surface plasmon resonance,triplet-triplet annihilation,photon upconversion
更新于2025-09-10 09:29:36
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Silica Nanoparticles with Up-conversion Fluorescence Based on Triplet-Triplet Annihilation Mechanism for Specific Recognition of Apoptosis Cells
摘要： Discriminating of live and apoptotic cells is a crucial task in the research of pharmacology, biology, pathology, and medicine science. Recently, up conversion (UC) luminescent materials have appealed much attention due to their unique ability to convert low energy excitation photons to high energy ones. However, UC fluorescence has not been employed in the field of discriminating of live and apoptotic cells. We presented a facile, and cost-less St?ber method to fabricate robust silica nanoparticles (SiO2 UCNPs) exhibiting several merits, such as narrow size distribution, and UC luminescence. SiO2 UCNPs could discriminate live and apoptosis cells by taking advantage of the unique surface property of SiO2 UCNPs for the first time. This work is also the first demonstration of the use of single photon excited UC fluorescence derived from nanoparticles for biological recognition of a specific type of cells.
关键词： Apoptosis Cells,Triplet-Triplet Annihilation Mechanism,Silica Nanoparticles,Up-conversion Fluorescence
更新于2025-09-09 09:28:46
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Solving the oxygen sensitivity of sensitized photon upconversion in life science applications
摘要： The conversion of low-energy light into high-energy light, also known as upconversion, can be exploited in life science applications such as bioimaging and phototherapy. Sensitized triplet–triplet annihilation upconversion (sTTA-UC) is one type of upconversion in which a photosensitizer is excited using a low-energy light and then transfers energy to an annihilator that emits at much higher energy. Changing the molecular components enables the fine-tuning of excitation and emission wavelengths. sTTA-UC is an appealing approach because it results in high upconversion efficiencies. However, its sensitivity to the presence of dioxygen in living cells and biological tissues is problematic. In this Review , the essential requirements of sTTA-UC for bio-nanodevices and life science applications are outlined before discussing the different ways to circumvent the dioxygen sensitivity of sTTA-UC.
关键词： phototherapy,dioxygen sensitivity,sensitized triplet–triplet annihilation upconversion,bioimaging,upconversion
更新于2025-09-09 09:28:46
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Photon Upconverted Circularly Polarized Luminescence via Triplet-Triplet Annihilation
摘要： Circularly polarized luminescent materials are of increasing attention due to their potential applications in advanced optical technologies, such as chiroptical devices and optical sensing. Recently, in all reported circularly polarized luminescent materials, high-energy excitation results in low-energy or downconverted circularly polarized luminescence (CPL) emission. Although photon upconversion—i.e., the conversion of low-energy light into higher-energy emission, with a wide variety of applications—has been widely reported, the integration of photon upconversion and CPL in one chiral system to achieve higher-energy CPL emission has never been reported. Herein, a brief review is provided of recent achievements in photon-upconverted CPL via the triplet–triplet annihilation mechanism, focusing on the amplified dissymmetry factor glum through energy transfer process and dual upconverted and downconverted CPL emission through chirality and energy transfer process.
关键词： triplet–triplet annihilation,photon upconversion,energy transfer,triplet energy migration,circularly polarized luminescence
更新于2025-09-04 15:30:14