Fan Liao

Bio: Fan Liao is an academic researcher from University of Science and Technology of China. The author has contributed to research in topics: Phosphorescence & Triplet state. The author has an hindex of 3, co-authored 8 publications receiving 80 citations.

Proton-Activated "Off-On" Room-Temperature Phosphorescence from Purely Organic Thioethers.

Abstract: Room-temperature phosphorescence (RTP)-based sensors have distinctive advantages over the fluorescence counterparts, such as larger Stokes shifts and longer lifetimes. Unfortunately, almost all RTP sensors are operated on quenching-based mechanisms given the sensitive nature of the emissive triplet state. Here we report a type of thioether RTP molecules that shows RTP "turn-on" when volatile acid vapors such as HCl are in contact. To elucidate the underlying mechanism, model thioethers containing different donor/acceptor combinations are investigated via fluorescence spectroscopy and theoretical calculations aided by molecular coordinates obtained from single-crystal X-ray diffraction. It is revealed that a charge-transfer character in the phosphorescence state is crucial. The "turn-on" design concept may significantly broaden the sensing application scope for organic RTP molecules.

An Organic Host–Guest System Producing Room-Temperature Phosphorescence at the Parts-Per-Billion Level

Abstract: Manipulation of long-lived triplet excitons in organic molecules is key to applications including next-generation optoelectronics, background-free bioimaging, information encryption, and photodynamic therapy. However, for organic room-temperature phosphorescence (RTP), which stems from triplet excitons, it is still difficult to simultaneously achieve efficiency and lifetime enhancement on account of weak spin-orbit coupling and rapid nonradiative transitions, especially in the red and near-infrared region. Herein, we report that a series of fluorescent naphthalimides-which did not originally show observable phosphorescence in solution, as aggregates, in polymer films, or in any other tested host material, including heavy-atom matrices at cryogenic temperatures-can now efficiently produce ultralong RTP (ϕ=0.17, τ=243 ms) in phthalimide hosts. Notably, red RTP (λRTP =628 nm) is realized at a molar ratio of less than 10 parts per billion, demonstrating an unprecedentedly low guest-to-host ratio where efficient RTP can take place in molecular solids.

Waterborne invisible fluorescent anti-counterfeiting ink as well as preparation method and application method thereof

Abstract: The invention provides waterborne invisible fluorescent anti-counterfeiting ink as well as a preparation method and an application method thereof. Fluorescent molecules in a used dyestuff water solution are not absorbed in a visible light region, so that the ink is colorless and transparent under a common sunlight condition and is completely invisible, and can display bright fluorescent light under ultraviolet irradiation, and furthermore, the contrast ratio and the anti-counterfeiting safety are improved; meanwhile, the waterborne invisible fluorescent anti-counterfeiting ink system providedby the invention takes water as a dissolution carrier; compared with previous oily dyestuffs, the waterborne invisible fluorescent anti-counterfeiting ink is safe and nontoxic, no volatile organic gasis generated and no pollution is caused; the consumption of resources is reduced and the environment protection cost is reduced; the ink has no burning and explosion risks and the safety of a workingenvironment is improved; furthermore, the waterborne invisible fluorescent anti-counterfeiting ink provided by the invention has a fluorescent color so that the problem that the color of a current fluorescent anti-counterfeiting dyestuff is single is overcome.

Assembling-Induced Emission: An Efficient Approach for Amorphous Metal-Free Organic Emitting Materials with Room-Temperature Phosphorescence

Abstract: ConspectusPure organic emitting materials with room-temperature phosphorescence (RTP), showing large Stokes shifts with long emitting lifetime, low preparation cost, good processability, and wide a...

Pure Organic Room Temperature Phosphorescence from Excited Dimers in Self-Assembled Nanoparticles under Visible and Near-Infrared Irradiation in Water.

Abstract: Pure organic room temperature phosphorescence (RTP) has unique advantages and various potential applications. However, it is challengeable to achieve organic RTP under visible and near-infrared (NIR)-light excitation, especially in aqueous solution. Herein we assemble difluoroboron β-diketonate compounds to form organic nanoparticles (NPs) in water. The resulting NPs are able to show efficient RTP, effective uptake, and bright imaging of HeLa cells under both visible- and NIR-light excitation. More strikingly, spectroscopic study, single-crystal X-ray diffraction, and DFT calculation reveal that the efficient RTP in organic NPs is originated from dimers in their excited states. The multiple interactions and intermolecular charge transfer in the dimer structures are of significance in promoting the production of dimer triplet excited states and suppressing the nonradiative decays to boost the RTP under visible- and NIR-light irradiation in water.

Ultralong UV/mechano-excited room temperature phosphorescence from purely organic cluster excitons.

Abstract: Purely organic room temperature phosphorescence (RTP) has attracted wide attention recently due to its various application potentials. However, ultralong RTP (URTP) with high efficiency is still rarely achieved. Herein, by dissolving 1,8-naphthalic anhydride in certain organic solid hosts, URTP with a lifetime of over 600 ms and overall quantum yield of over 20% is realized. Meanwhile, the URTP can also be achieved by mechanical excitation when the host is mechanoluminescent. Femtosecond transient absorption studies reveal that intersystem crossing of the host is accelerated substantially in the presence of a trace amount of 1,8-naphthalic anhydride. Accordingly, we propose that a cluster exciton spanning the host and guest forms as a transient state before the guest acts as an energy trap for the RTP state. The cluster exciton model proposed here is expected to help expand the varieties of purely organic URTP materials based on an advanced understanding of guest/host combinations. Purely organic ultralong room temperature phosphorescence (URTP) attracts attention but high efficiencies are rarely achieved. Here the authors use ultrafast spectroscopy to investigate a system of 1,8-naphthalic anhydride in organic hosts and reveal that a cluster exciton forms as a transient state before the guest acts as an energy trap for the URTP state.

Recent Advances on Host-Guest Material Systems toward Organic Room Temperature Phosphorescence.

Abstract: The design and characterization of purely organic room-temperature phosphorescent (RTP) materials for optoelectronic applications is currently the focus of research in the field of organic electronics. Particularly, with the merits of preparation controllability and modulation flexibility, host-guest material systems are encouraging candidates that can prepare high-performance RTP materials. By regulating the interaction between host and guest molecules, it can effectively control the quantum efficiency, luminescent lifetime, and color of host-guest RTP materials, and even produce RTP emission with stimuli-responsive features, holding tremendous potential in diverse applications such as encryption and anti-counterfeiting, organic light-emitting diodes, sensing, optical recording, etc. Here a roundup of rapid achievement in construction strategies, molecule systems, and diversity of applications of host-guest material systems is outlined. Intrinsic correlations between the molecular properties and a survey of recent significant advances in the development of host-guest RTP materials divided into three systems including rigid matrix, exciplex, and sensitization are presented. Providing an insightful understanding of host-guest RTP materials and offering a promising platform for high throughput screening of RTP systems with inherent advantages of simple material preparation, low-cost, versatile resource, and controllably modulated properties for a wide range of applications is intended.