A polyhedral oligomeric silsesquioxanes (POSS) modified 8-hydroxyquinoline derivative (denoted as Q-POSS) was synthesized and used as a ligand to coordinate with lanthanide ions to obtain a series of lanthanide complexes Ln(Q-POSS)₃ (Ln = Er³⁺, Yb³⁺, Nd³⁺). The as-prepared lanthanide complexes have been characterized by FT-IR, UV–Vis, and elemental analysis. All these complexes showed the characteristic near-infrared (NIR) luminescence originated from the corresponding lanthanide ions under excitation. Compared with the unmodified counterparts LnQ₃ (HQ = 8-hydroxyquinoline), the Ln(Q-POSS)₃ complexes showed obviously increased emission intensity, which was ascribed mainly to the steric-hindrance effects of the POSS moiety in the ligands. It is believed that the POSS group could suppress undesired excimer formation and intermolecular aggregation, thus decreasing the concentration quenching effect of the corresponding lanthanide complexes.

The luminescent performances of near-infrared (NIR) lanthanide (Ln) complexes were restricted greatly by vibration quenching of X-H (X = C, N, O) oscillators, which are usually contained in ligands and solvents. Encapsulating Ln³⁺ into a cavity of coordination atoms is a feasible method of alleviating this quenching effect. In this work, a novel ytterbium complex [Yb(DPPDA)₂](DIPEA) coordinated with 4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid (DPPDA) was synthesized and characterized by FT-IR, ESI-MS and elemental analysis. Under the excitation of 335 nm light, [Yb(DPPDA)₂](DIPEA) showed two emission peaks at 975 and 1011 nm, respectively, which were assigned to the characteristic ²F_5/2 → ²F_7/2 transition of Yb³⁺. Meanwhile, this ytterbium complex exhibited a plausible absolute quantum yield of 0.46% and a luminescent lifetime of 105 μs in CD₃OD solution. In particular, its intrinsic quantum yield was calculated to be 12.5%, and this considerably high value was attributed to the near-zero solvent molecules bound to Yb³⁺ and the absence of X-H oscillators in the first coordination sphere. Based on experimental results, we further proposed that the sensitized luminescence of [Yb(DPPDA)₂](DIPEA) occurred via an internal redox mechanism instead of an energy transfer process.

Single-molecule white-light emitters have attracted much attention due to their potential applications in white organic light-emitting diodes (WOLEDs). Their key advantage lies in the ability to use a simple device structure, akin to that of monochromatic OLEDs, to produce WOLEDs. This approach not only simplifies the fabrication process but also reduces costs, improves device stability, and provides a shortcut for the rapid commercialization of WOLEDs. In this study, two novel single-molecule white-light emitters, SRFR-1PTZ (10-(4′-(9H-9,9′-spirobi[fluoren]-2-yl)-4a,10a-dihydro-10H-phenothiazine) and SRFR-2PTZ (2,7-bis(4a,10a-dihydro-10H-phenothiazin-10-yl)-9,9′-spirobi[fluorene]), were designed and synthesized, and successfully implemented in WOLED devices. Comprehensive photophysical characterization revealed that both compounds exhibited dual-emission characteristics in dichloromethane solution, displaying simultaneous fluorescence and phosphorescence. Notably, thermally activated delayed fluorescence (TADF) was clearly observed for SRFR-1PTZ, whereas SRFR-2PTZ did not exhibit TADF behavior. Electroluminescence studies demonstrated that both SRFR-1PTZ and SRFR-2PTZ served as good color-stable cool-white-light emitters under driving voltages of 7–10 V.

Long persistent phosphors are widely used in many fields, such as LED, bioimaging, urgent lighting, temperature sensors, etc. Although green and blue long persistent phosphors are well developed, efficient orange-yellow long persistent phosphors are still relatively rare. In this work, a novel orange-yellow long-persistent phosphors Ca₂LuScGa₂Ge₂O₁₂:xPr³⁺ (CLSGGO:xPr³⁺, x = 0.003, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05) are prepared and systematically investigated through its crystal structural information, photoluminescence, and persistent luminescence properties. Under ultraviolet light excitation, these phosphors exhibit orange-yellow emission stemming from the ³P₀ and ¹D₂ multiple electron transitions in the 4f level of Pr³⁺ ion. In addition, the material exhibits bright persistent luminescence. The complex garnet matrix structure of Ca₂LuScGa₂Ge₂O₁₂ provides excellent conditions for the formation of traps. Through the testing of thermoluminescence curve and function fitting, the density and depth of traps are studied; also, the storage and release process of carriers in the material are calculated in detail. A reasonable persistent luminescence mechanism is proposed for CLSGGO:0.01Pr³⁺. This work enriches the research content of photoluminescence and long persistent luminescence of Pr³⁺-doped garnet-based phosphors and paves the way for the future research of long persistent luminescent materials doped with rare earth ions.

Thermochromic fluorescent materials have significant application prospects in the field of temperature sensing. In this study, based on the donor–acceptor–donor (D-A-D) strategy, two fluorescent molecules, MPT-1 and MPT-2, with fluorenyl cores and methoxy phenothiazine as donors, were synthesized via the Buchwald–Hartwig C–N cross-coupling reaction, and their structures were confirmed by ¹H NMR, ¹³C NMR and HRMS. Thermogravimetric analysis indicated that both compounds exhibited excellent thermal stability (T_d = 377 °C, 413 °C). Aggregation-induced emission (AIE) experiments showed that the emission peak blue-shifted by approximately 42–44 nm with increasing aggregation. Temperature-dependent fluorescence studies indicated that from 80 K to 300 K, the emission peaks of both molecules shifted continuously from the yellow region to the blue region. The relative sensitivities of MPT-1 and MPT-2 were 2.5% K⁻¹ and 2.19% K⁻¹, respectively, with CIE ΔE shifts of 0.19 and 0.18. This study elucidates the thermochromic mechanism of D-A-D-type fluorescent molecules, confirms the tunability of their emission colour in response to temperature, and provides theoretical guidance and experimental reference for the design of novel thermochromic fluorescent materials and their applications in temperature sensing.