Yixi Zhuang

K ⁺ incorporation induces local structural distortion in SrAl ₂ O ₄ :Eu ²⁺ ,Dy ³⁺ , enhancing the piezoelectric field to accelerate trapped-carrier release, tripling ML intensity and lowering the threshold to ∼0.01 mJ.

Circularly polarized luminescence (CPL), which encodes non-replicable optical information in the characteristics of chirality, wavelength, and time, holds significant promise for advanced information technologies. However, effective strategies for systematically regulating multiple optical properties remain elusive. Herein, we report a general approach that imparts hour-level dual-band persistent luminescence to CPL materials through the introduction of trap states into an organic host-guest molecular system. The electrons released from traps repopulate both the singlet and triplet states of the chiral guest molecules, producing dual-band white circularly polarized persistent luminescence for 4 h at room temperature. Systematic characterization reveals that two different chiral configurations leave the trap depth basically unaltered, while conferring pronounced CPL activity on these composites with a maximum luminescence dissymmetry factor g _lum of 1.6 × 10 ⁻³ /−2.3 × 10 ⁻³ . Leveraging these characteristics, we present a proof-of-concept demonstration of warm-white circularly polarized persistent luminescence materials for Morse-code encryption and multimodal information storage.

Recent studies have indicated that traps play a crucial role in determining characteristics of organic persistent luminescence, yet constructing traps with controllable depth remains highly challenging. Herein, we propose a host energy-level engineering strategy, which enables precise control of trap depth. Using the Randall-Wilkins method, the trap depth can be tuned from 0.38 to 0.72 eV without altering emission wavelength and the result aligns well with density functional theory calculations. Specifically, a host-guest material namely CPND@DPEPO, which has a deep trap of ~ 0.72 eV, exhibits deep-blue persistent luminescence lasting for 27 hours and efficient energy storage over 14 days at room temperature. By utilizing these trap-containing materials as the emission layer in organic light-emitting diodes, we develop a pixel-programmable information storage device. This work establishes a fundamental principle for designing organic materials with controllable trap depth, potentially expanding their applications in night tracing, military communication and biological imaging.

Blue phosphorescent OLEDs (Ph-OLEDs) have long faced critical challenges in efficiency, stability and brightness, which are crucial for advanced display. Herein, we introduce two novel Ir(III) emitters featuring a 3,6-di(tert-butyl)-9H-carbazolyl (tBuCz) substituted tridentate carbene pincer ligand, significantly improving efficiency and stability. The tBuCz- m -CF3 and tBuCz- p -CF3 complexes are designed to enhance steric encumbrance and minimize exciton accumulation. These innovations lead to exceptional photoluminescence quantum yields (PLQY) of 98% and an impressive decay rate constant of 7.97 × 10⁵ s⁻¹ in doped thin films. The Ph-OLEDs emit blue light with a peak wavelength of 485 nm and CIE coordinates of (0.175, 0.446), exhibiting a peak external quantum efficiencies (EQE) of 31.62% and brightness up to 214,255 cd m⁻². Notably, they shown minimal efficiency roll-off, retaining an EQE of 27.76% at 10,000 cd m⁻², and 20.58% at 100,000 cd m⁻². These consistent performances across various brightness levels represent a significant milestone for blue Ph-OLED technology. The devices also exhibit impressive stability, with an operational lifetime (LT₅₀, the time taken for luminance to decrease by 50%) reaching 1237 h at 1000 cd m⁻², setting new benchmarks for blue Ph-OLEDs. To enhance the color purity, hyper-OLEDs were developed with a full width at half maximum (FWHM) of 20 nm and the CIEy of 0.233, achieving an EQE_m of 29.78% and LT₅₀ of 318 h at 1000 cd m⁻². We also fabricated the active-matrix (AM) blue Hyper-OLEDs with 400 pixels per inch to demonstrate their application in AM displays.

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Luminescence in organics that lasts for seconds to a few hours after light excitation has been reported recently, showcasing significant application potentials in flexible electronics and bioimaging. In contrast, long‐lasting luminescence that can be electrically excited, whether in organics or inorganics, is much rarer and often less efficient. In this study, we report persistent luminescence (PersL) in organic light‐emitting diodes (OLEDs) that lasts over 100 s and an energy storage effect beyond 60 min after charging with a direct‐current electric field. Thermoluminescence studies reveal that the PersL in OLEDs is induced by traps formed in a host‐guest molecular system serving as an emission layer (EML) with a trap depth of approximately 0.24 eV, consistent with the results from the same EML materials under light irradiation. Integrating results from electronic spin resonance, and density functional theory calculations, we propose a model delineating the charge carrier migration responsible for the trap‐induced PersL in OLEDs. This study on trap‐induced PersL in OLEDs may deepen our understanding of the luminescence mechanism in organic semiconductors and pave the way for expanding their applications in optoelectronics, energy storage and biological detection technologies. image