State Key Laboratory of Luminescent Materials and Devices

Owing to the unique mechanism of photoelectron storage and release, long persistent phosphorescence, also called long persistent luminescence or long lasting afterglow/phosphorescence, plays a pivotal role in the areas of spectroscopy, photochemistry, photonics and materials science. In recent years, more research has focused on the manipulation of the morphology, operational wavebands and persistent duration of long persistent phosphors (LPPs). These desired achievements stimulated the growing interest in designing bio-labels, photocatalysts, optical sensors, detectors and photonic devices. In this review, we present multidisciplinary research on synthetic methods, afterglow mechanisms, characterization techniques, materials system, and applications of LPPs. First, we introduce the recent developments in LPPs for the synthesis of nanoparticles from the aspects of particle sizes, monodispersity and homogeneity based on the urgent application of bio-imaging. In the later sections, we present the possible mechanisms, which involve the variation of trap distribution during the trapping and de-trapping process, complicated photo-ionization reaction of trap site levels and impurity centers together with their corresponding migration kinetics of carriers. Meanwhile, we emphasize the characterization techniques of defects, used to qualitatively or quantitatively describe the types, concentrations and depths of the traps. This review article also highlights the recent advances in suggested LPPs materials with a focus on the LPPs' hosts and optically active centers as well as their control, tuning and intrinsic links. We further discuss the classification of LPPs based on the different emission and excitation wavebands from the ultraviolet to the near-infrared region along with an overview of the activation mode of afterglow. Afterwards, we provide an exhibition of new products towards diverse application fields, including solar energy utilization, bio-imaging, diagnosis, and photocatalysts. Finally, we summarize the current achievements, discuss the problems and provide suggestions for potential future directions in the aforementioned parts.

Zero-dimensional (0D) all-inorganic/organic-inorganic metal halides, as emerging luminescent materials, have attracted unparalleled interest from versatile perspectives due to their unique crystallographic/electronic structures with isolated building units and fascinating optical characteristics. However, significant challenges still exist for 0D metal halides, including their chemical molecular design, photoluminescence (PL) mechanism, PL modification and applications. In this review, we summarize the 0D metal halides through the classification of all-inorganic and organic-inorganic hybrid metal halides, and further emphasize the unique role of B-site cations with different electronic configurations in the PL process. Furthermore, the PL mechanisms focusing on the self-trapped excitons (STEs) model and PL regulation engineering are examined to explore their extraordinary PL properties and further reveal new application prospects. This review aims to provide in-depth insight into the structure-luminescence-application relationship of 0D metal halides and pave the way for the realization of next-generation high-performance luminescent materials.

Phototheranostics represents a promising direction for modern precision medicine, which has recently attracted great research interest from multidisciplinary research areas. Organic optical agents including small molecular fluorophores, semiconducting/conjugated polymers, aggregation-induced emission luminogens, etc. with tuneable photophysical properties, high biosafety and biocompatibility, facile processability and ease of functionalization have delivered encouraging performance in disease phototheranostics. This review summarizes the recent progress of organic phototheranostic agents with an emphasis on the main strategies to manipulate the three excitation energy dissipation pathways, namely, radiative decay, thermal deactivation, and intersystem crossing, with the assistance of a Jablonski diagram, which particularly showcases how the Jablonski diagram has been guiding the design of organic agents from molecule to aggregate levels to promote the disease phototheranostic outcomes. Molecular design and nanoengineering strategies to modulate photophysical processes of organic optical agents to convert the absorbed photons into fluorescent/phosphorescent/photoacoustic signals and/or photodynamic/photothermal curing effects for improved disease phototheranostics are elaborated. Noteworthily, adaptive phototheranostics with activatable and transformable functions on demand, and regulation of excitation such as chemiexcitation to promote the phototheranostic efficacies are also included. A brief summary with the discussion of current challenges and future perspectives in this research field is further presented.

; n≥ 2, m≥ 1). Since Ma and Yang proposed the hot exciton mechanism for OLED material design in 2012, there have been many reports aiming at the design and synthesis of novel hot exciton luminogens. Herein, we present a comprehensive review of the recent progress in hot exciton materials. The developments of the hot exciton mechanism are reviewed, the fundamental principles regarding molecular design are discussed, and representative reported hot exciton luminogens are summarized and analyzed, along with their structure-property relationships and OLED applications.

Aggregation-induced emission (AIE) is a unique and significant photophysical phenomenon that differs greatly from the commonly acknowledged aggregation-caused emission quenching observed for many π-conjugated planar chromophores. The mechanistic decipherment of the AIE phenomenon is of high importance for the advance of new AIE systems and exploitation of their potential applications. Propeller-like 2,3,4,5-tetraphenylsiloles are archetypal AIE-active luminogens, and have been adopted as a core part in the design of numerous luminescent materials with diverse functionalities. In this review article, we elucidate the impacts of substituents on the AIE activity and shed light on the structure-property relationship of siloles, with the aim of promoting the judicious design of AIE-active functional materials in the future. Recent representative advances of new silole-based functional materials and their potential applications are reviewed as well.

Abstract The discovery of high efficiency narrow‐band green‐emitting phosphors is a major challenge in backlighting light‐emitting diodes (LEDs). Benefitting from highly condensed and rigid framework structure of UCr 4 C 4 ‐type compounds, a next‐generation narrow green emitter, RbLi(Li 3 SiO 4 ) 2 :Eu 2+ (RLSO:Eu 2+ ), has emerged in the oxide‐based family with superior luminescence properties. RLSO:Eu 2+ phosphor can be efficiently excited by GaN‐based blue LEDs, and shows green emission at 530 nm with a narrow full width at half maximum of 42 nm, and very low thermal quenching (103%@150 °C of the integrated emission intensity at 20 °C), however its chemical stability needs to be improved later. The white LED backlight using optimized RLSO:8%Eu 2+ phosphor demonstrates a high luminous efficacy of 97.28 lm W −1 and a wide color gamut (107% National Television System Committee standard (NTSC) in Commission Internationale de L'Eclairage (CIE) 1931 color space), suggesting its great potential for industrial applications as liquid crystal display (LCD) backlighting.

Abstract Phosphor-converted white LEDs rely on combining a blue-emitting InGaN chip with yellow and red-emitting luminescent materials. The discovery of cyan-emitting (470–500 nm) phosphors is a challenge to compensate for the spectral gap and produce full-spectrum white light. Na 0.5 K 0.5 Li 3 SiO 4 :Eu 2+ (NKLSO:Eu 2+ ) phosphor was developed with impressive properties, providing cyan emission at 486 nm with a narrow full width at half maximum (FWHM) of only 20.7 nm, and good thermal stability with an integrated emission loss of only 7% at 150 °C. The ultra-narrow-band cyan emission results from the high-symmetry cation sites, leading to almost ideal cubic coordination for UCr 4 C 4 -type compounds. NKLSO:Eu 2+ phosphor allows the valley between the blue and yellow emission peaks in the white LED device to be filled, and the color-rendering index can be enhanced from 86 to 95.2, suggesting great applications in full-spectrum white LEDs.

A non-fullerene acceptor with a high relative dielectric constant (<italic>ε</italic>_r) over 9 is developed. It offers an efficiency of 8.5%, which is the best result for organic solar cells employing high <italic>ε</italic>_r materials. Further research should focus on morphology optimization to make high <italic>ε</italic>_r practically useful in devices.

Ag nanoparticles were deposited on the surface of g-C3N4 by a chemical reduction method to increase visible-light absorption via the localized surface plasmon resonance effect, resulting in the reduced recombination of photo-generated electron-holes and enhanced photocatalytic activity. The Ag/g-C3N4 composite with a Ag loading of 3 wt% has the optimum photoactivity that is almost 3.6 and 3.4 times higher than pure g-C3N4 and the same photocatalysis system which has been reported, respectively. Fluorescein was introduced as a photosensitizer and H2 evolution soared to 2014.20 μmol g(-1) h(-1) and the rate is even about 4.8 times higher than that of the 3 wt% Ag/g-C3N4 composite. The chemical structure, composites, morphologies and optical properties of the obtained products are well-characterized by XRD, FTIR, TEM, EDS, XPS and UV-Vis DRS. Meanwhile, the photocatalyst exhibits high stability and reusability.

A Ti₃C₂–CuS//Ti₃C₂ asymmetric supercapacitor device exhibited an energy density of 15.4 W h kg⁻¹ at a power density of 750.2 W kg⁻¹.

By processing PTzBI:N2200 blends with green solvent 2-methyltetrahydrofuran, all-PSCs with a power conversion efficiency over 9% can be achieved.

As a new non-invasive treatment method, photodynamic therapy (PDT) has attracted great attention in biomedical applications. The advantages of possessing fluorescence for photosensitizers have made it possible to combine imaging and diagnosis together with PDT. The unique features of aggregation-induced emission (AIE) fluorogens provide new opportunities for facile design of light-up probes with high signal-to-noise ratios and improved theranostic accuracy and efficacy for image-guided PDT. In this review, we summarize the recent advances of AIE light-up probes for PDT. The strategies and principles to design AIE photosensitizers and light-up probes are firstly introduced. The application of AIE light-up probes in photodynamic antitumor and antibacterial applications is further elaborated in detail, from binding/targeting-mediated, reaction-mediated, and external stimuli-mediated light-up aspects. The challenges and future perspectives of AIE light-up probes in the PDT field are also presented with the hope to encourage more promising developments of AIE materials for phototheranostic applications and translational research.

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health.

Semi-transparent photovoltaic (ST-PV) technologies can be applied to replace facades and roofs in conventional buildings and coatings on vehicles to produce energy from sunlight.

Advances in organic photovoltaic technologies have always been closely associated with a deeper understanding of bulk-heterojunction (BHJ) microstructure morphology, which is generally governed by the ink-formulation based on a single solvent or solvent mixtures.

Metal halide perovskites have received much attention for their application in light-emitting diodes (LEDs) in the past several years. Rapid progress has been made in efficient green, red, and near-infrared perovskite LEDs. However, the development of blue perovskite LEDs is still lagging far behind. Here, we report efficient sky-blue perovskite LEDs by rearranging low-dimensional phase distribution in quasi-2D perovskites. We incorporated sodium ions into the mixed-Cl/Br quasi-2D perovskites with phenylethylammonium as the organic spacer and cesium lead halide as the inorganic framework. The inclusion of the sodium ion was found to significantly reduce the formation of the n = 1 phase, which was dominated by nonradiative transition, and increase the formation of other small-n phases for efficient exciton energy transfer. By managing the phase distribution, a maximum external quantum efficiency (EQE) of 11.7% was achieved in the sky-blue perovskite LED, with a stable emission peak at 488 nm. Further optimizing the phase distribution and film morphology with Pb content, we demonstrated the sky-blue devices with the average EQE approaching 10%. This strategy of engineering phase distribution of quasi-2D perovskites with a sodium ion could provide a useful way for the fabrication of high-performance blue perovskite LEDs.

To enlarge the family of AIEgens and to enrich their functions, new AIEgens are in high demand. In this work, we report a new kind of AIEgen based on tetraphenylpyrazine (TPP), which could be readily prepared under mild reaction conditions. Furthermore, we show that the TPP derivatives possess a good thermal stability and their emission could be fine-tuned by varying the substituents on their phenyl rings. It is anticipated that TPP derivatives could serve as a new type of widely utilized AIEgen, based on their facile preparation, good thermo-, photo- and chemostabilities, and efficient emission.

A<italic>meta</italic>-linked donor–acceptor (D–A) structure was utilized to achieve high-efficiency and colour-purity near ultraviolet (NUV) in organic light-emitting diodes (OLEDs).

Abstract Doping impurity ions into semiconductor luminescent materials offers a unique pathway for inducing new emission centers and enabling photoluminescence (PL) tuning. Among various luminescence materials, doping Mn 2+ into metal halide perovskites becomes a hot topic since Mn 2+ ions demonstrate an energy transfer route from host to dopants, resulting in interesting photophysical properties. This review aims to discuss the PL properties of Mn 2+ ions in halide perovskites nanocrystals or bulk crystals with different structural dimensions and local environments (MnX 4 2– tetrahedron, MnX 6 2– octahedron, or shortest Mn─Mn distance). In this regard, the effects of Mn 2+ doping on the PL properties and their modifications are summarized. Variable ion exchange dynamics, increased emission intensity, and enhanced stability induced by Mn 2+ doping are analyzed. These results also provide beneficial insights into applications of the doped luminescent halide perovskites. Finally, the present challenges in Mn 2+ ‐doped luminescent halide perovskites are elaborated.

-TPA-PIO-mediated PDT has high potential as a precursor of the immunostimulatory effect for immunotherapy. This work presents a comprehensive protocol for Type I-based purely organic PSs and highlights the significance of considering the working mechanism in the design of PSs for the optimization of cancer treatment protocols.