CIE Coordinates Research Articles

Through‐Space vs Through‐bond Charge Transfer Fluorophores as Emitters for Efficient Blue Electroluminescent Devices

AbstractHerein, we report the design, synthesis, and properties of two donor‐π‐acceptor (D‐π‐A) charge transfer fluorophores pursuing an efficient deep blue emitter for organic light‐emitting diode (OLED). TCyCN and TPhCN comprise triphenylamine as a donor and benzonitrile as an acceptor connecting by either [2.2]paracyclophane (Cy) as a through‐space π‐linker or phenyl ring (Ph) as a through‐bond π‐linker, respectively. In thin film, TCyCN shows deep blue emission with moderate fluorescence efficiency, while TPhCN displays cyan blue emission with a high fluorescence efficiency. The two molecules feature hybridized local and charge‐transfer states with good thermal stability and balanced charge transport properties. They are successfully employed as non‐doped blue emissive layers in OLEDs. The TCyCN‐based device emits deep blue light peaked at 425 nm (CIE coordinates of (0.157, 0.076)) with a moderate electroluminescent (EL) performance (EQEmax=3.23 % and CEmax=2.06 cd A−1), while the TPhCN‐based device attains an excellent EL performance (EQEmax=6.24 % and CEmax=8.26 cd A−1) with cyan blue emission peaked at 490 nm. This work provides insight into the relationship between molecular design and properties of D‐π‐A emitters, offering a guideline for tailoring new organic compounds for organic optoelectronics.

Preparation and Characterization of Red, Green, Blue (RGB) and White Luminescent Inorganic/Organic Polymers Through In Situ Polymerization.

YVO4:Eu3+/PMMA, LaPO4:Ce3+,Tb3+/PMMA and CaWO4/PMMA nanocomposites were prepared by in situ polymerization method with hydrophobic YVO4:Eu3+, LaPO4:Ce3+,Tb3+ and CaWO4 nanoparticles as the filler and poly (methyl methacrylate) (PMMA) as the host material. All the nanoparticles and composites have been well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), the thermogravimetric analysis (TGA), photoluminescence excitation, and emission spectra and luminescence decays. YVO4:Eu3+/PMMA, LaPO4:Ce3+,Tb3+/PMMA, CaWO4/PMMA nanocomposites exhibit strong red, green and blue photoluminescence upon 254nm UV excitation, respectively. The yellow and white LED nanocomposites with CIE coordinates of (0.411, 0.498) and (0.334, 0.359) were obtained by triply integrating the red, green and blue nanoparticles into PMMA. Thanks to the abundant luminescent colors from RGB to yellow and white in these polymer composites under UV excitation, they can be potentially used in various optoelectronic fields.

Two New Coordination Polymers: Crystal Structures and Fluorescence Properties.

A new Ni (II) metal-organic frameworks with the formula [Ni2(HL)2(H2O)4]∙3H2O (1) and a novel phenoxo-O bridged rare-earth dinuclear Schiff base complex with the formula [La2(dbm)4L·CH3OH] (2), where the HL2- is the partial deprotonated of the organic ligand H3L, and H2L is a bis-Schiff foundation ligand (H3L = 4,6-dioxo-1,4,5,6-tetrahydro-1,3,5-triazine-2-carboxylic acid, H2L = N, N'-bis (2-hydroxy-3-methoxybenzylidene) -propane-1,2-diamine, Hdbm = dibenzoylmethane), have been successfully generated under the solvothermal condition. The targeted product sample of 1 and 2 has been fully characterized by single-crystal X-ray data, elemental analysis, FT-IR, powder X-ray diffraction, and thermogravimetric analysis. Furthermore, fluorescence performance testing of the complexes revealed that in complex 1, H3L forms a rigid chain through coordination with Ni2+ ions and further forms a highly rigid three-dimensional framework within the hydrogen bond network, resulting in fluorescence enhancement of up to 13.7-fold, displaying deep blue fluorescence with CIE coordinates of (0.1626, 0.1375). In contrast, complex 2 forms only discrete zero-dimensional molecules and exhibits light blue fluorescence with CIE coordinates of (0.1744, 0.2306). This demonstrates their potential as fluorescent materials.

High‐Efficiency Deep‐Blue Solution‐Processed Organic Light‐Emitting Diodes Using Carbazole Dendrons Modified Hybridized Local and Charge‐Transfer Emitters

AbstractIn the pursuit of efficient and cost‐effective organic light‐emitting diodes (OLEDs), the development of solution‐processed hybridized local and charge transfer (HLCT) emitters presents a promising approach. HLCT materials uniquely integrate the advantages of both singlet and triplet excitons, surpassing the traditional spin statistical limit of 25 % while offering high photoluminescence efficiency and balanced charge transport properties. Herein, we report the synthesis and characterization of two new deep blue, solution‐processable HLCT fluorophores, G1FTPI and G2FTPI. These compounds incorporate fluorenyl carbazole dendron units into the HLCT luminogenic triphenylamine‐phenanthroimidazole (TPI) molecule. Their HLCT and photoluminescence (PL) properties were experimentally and theoretically investigated using solvation effects and density functional theory (DFT) calculations. The molecules exhibit deep blue emission with a high solid‐state fluorescence quantum yield, good solution‐processed film‐forming quality, and high hole mobility values of 2.18–2.61×10−6 cm2 V−1 s−1. Both compounds were successfully employed as non‐doped emissive layers in solution‐processed OLEDs, demonstrating excellent electroluminescent (EL) performance. Notably, the G2FTPI‐based device emitted a deep blue light at 432 nm with CIE coordinates of (0.158, 0.098) and achieved a maximum current efficiency (CEmax) of 3.13 cd A−1 and a maximum external quantum efficiency (EQEmax) of 5.30 %.

Tunable green-blue luminescence of Dy2O3 doped borosilicate glasses for optoelectronic devices

The optical-structural correlated properties of the 40B2O3−40SiO2−10V2O5−(10−x)Fe2O3−xDy2O3 system, where 2, 4, and 6 mol%, were studied. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) confirmed the glassy and amorphous nature of the samples. Adding Dy2O3 promoted the formation of bridging oxygens (upto 4 mol%) by converting BO3 into BO4 units, however, above 4 mol% Dy2O3 act as a modifier. The optical band gap increased from 3.70 to 4.01 eV, while the refractive index decreased from 2.23 to 2.16. The CIE coordinates indicated that the emission spectra fall within the green-blue region. The as-prepared sample exhibited the highest correlated colour temperature value above 5000 K, suggesting its suitability for cool light-emitting diodes sensitive to human vision. These glasses have potential applications in light-emitting diodes and optoelectronic devices.

Synergistic π-Extension and Peripheral-Locking of B/N-Based Multi-Resonance Framework Enables High-Performance Pure-Green Organic Light-Emitting Diodes.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters offer natural advantages for creating power-efficient, wide-color-gamut OLEDs. However, current green MR-TADF emitters face challenges in simultaneously achieving high color purity and efficient reverse inter-system crossing (RISC), leading to suboptimal device performance. In this study, we propose a synergistic molecular design approach that combines π-extension and peripheral locking to address these challenges. This approach allows for the construction of quadruple borylated MR-TADF emitters that not only deliver precisely tuned pure-green emission with a narrow full width at half maximum (FWHM) of 15 nm, but also exhibit close-to-unity quantum yield, rapid RISC, and optimal horizontal dipole orientation. The resulting sensitizer-free OLED approaches the BT.2020 standard with CIE coordinates of (0.18, 0.74) and demonstrates impressive external quantum efficiency (EQE) of 36.6% at maximum and 31.8% at 1000 cd m-2. Additionally, the device shows good operational stability, with a lifetime (LT80) of 485 hours at an initial luminance of 1000 cd m-2. This study hence offers a promising molecular design strategy that effectively enhances the comprehensive OLED performance.

Synergistic π‐Extension and Peripheral‐Locking of B/N‐Based Multi‐Resonance Framework Enables High‐Performance Pure‐Green Organic Light‐Emitting Diodes

Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters offer natural advantages for creating power‐efficient, wide‐color‐gamut OLEDs. However, current green MR‐TADF emitters face challenges in simultaneously achieving high color purity and efficient reverse inter‐system crossing (RISC), leading to suboptimal device performance. In this study, we propose a synergistic molecular design approach that combines π‐extension and peripheral locking to address these challenges. This approach allows for the construction of quadruple borylated MR‐TADF emitters that not only deliver precisely tuned pure‐green emission with a narrow full width at half maximum (FWHM) of 15 nm, but also exhibit close‐to‐unity quantum yield, rapid RISC, and optimal horizontal dipole orientation. The resulting sensitizer‐free OLED approaches the BT.2020 standard with CIE coordinates of (0.18, 0.74) and demonstrates impressive external quantum efficiency (EQE) of 36.6% at maximum and 31.8% at 1000 cd m‐2. Additionally, the device shows good operational stability, with a lifetime (LT80) of 485 hours at an initial luminance of 1000 cd m‐2. This study hence offers a promising molecular design strategy that effectively enhances the comprehensive OLED performance.

Influence of carbon dots as modifier and SiO2 shell coating as a protecting layer in YAlO3:Cr3+ phosphors for multimodal applications

This study focuses on the synthesis of SiO2-coated carbon dots (CDs) grafted onto YAlO3:Cr3+ (YAP:Cr3+) nanophosphors (NPs) through a combustion method. The CDs enhance the absorption cross-section of Cr3+ ions, significantly boosting the luminescence of YAP:Cr3+ by 19.29-fold. Further improvement is achieved with a SiO2 coating, leading to a 48.73-fold increase in photoluminescence intensity. The NCs are colour tunable, with emissions ranging from pinkish-red to blue, depending on the concentration of CDs and the excitation wavelength. These properties make them suitable for diverse applications, such as ratio metric fluorescence sensors for detecting Fe3+ ions within the 0–350 µM range, with high sensitivity (0.2 µM) and a low detection limit (4.93 μM). Additionally, they serve as material for white light-emitting diodes (W-LEDs), achieving CIE coordinates of (0.31, 0.30) and a rendering index of 94. The NCs also function as an optical thermometer with a sensitivity of 0.31 % K−1 at 320 K, making them ideal for temperature sensing applications. Moreover, their stability and dual-emissive nature make them highly effective in latent fingerprints (LFPs) detection, enabling high-resolution, level III fingerprint analysis. The dual emission properties of CDs and Cr3+ ions position these NCs as multifunctional materials, suitable for optical sensing, lighting, and security applications.

The effect of Ce3+ ions on the optical, and radiation shielding properties in Ba–Sn borophosphate glass

This study aims to investigate the structural, optical, and mechanical properties of Ce3+ doped Barium Tin Borophosphate glass for potential applications in nuclear radiation shielding. The Ce3+ Doped Barium Tin Borophosphate glass (50B2O3+20 P2O5+10TiO2+6SrCO3+4SnO+ 4BaF2+5BaCO3+1Ce2O3) was produced according to earlier research, melt quenching method. The amorphous nature of Ce3+ Doped Barium Tin Borophosphate glass was verified by powder X-ray diffraction investigation. The Ce3+ Doped Barium Tin Borophosphate glass's functional groups were determined using Fourier transform-RAMAN and Fourier transform infrared spectroscopy. Using Ultraviolet-Visible spectroscopy the Ce3+ Doped Barium Tin Borophosphate glass was examined. These properties included its optical band gap, extinction coefficient, optical conductivity, and refractive index. Using EDAX and SEM analyses, the chemical compositions and surface morphology of the Ce3+ Doped Barium Tin Borophosphate glass were examined. Ce3+ doped barium tin Borophosphate glass was studied in terms of its excitation and emission spectra using the photoluminescence technique. The glass's CIE coordinates were also looked at. Additionally, the mass attenuation coefficient, half-value layer, mean free path, tenth value layer, and EABF were studied concerning the glass's gamma-ray shielding qualities using the Phy-X software.

The red or orange emitters based on phenylquinoline or trifluoromethylpyridine iridium complexes with dimesitylboryl or diphenylphosphoryl fluorenyl unit

Novel complexes bis[2-(4-(7-dimesitylboryl-9,9-diethylfluoren-2-yl)phenyl)-4-phenyl- quinolyl-C2, N] iridium (acetylacetonate or 2-picolinic acid), bis[2-[4-(7-diphen- ylphosphoryl-9,9-diethylfluoren-2-yl)phenyl)-4-phenylquinolyl-C2, N]iridium (acetyl-acetonate or 2-picolinic acid), and bis[2-(7-dimesitylboryl-9, 9′-diethylfluoren-2-yl)-5-trifluoromethylpyridinto-C3, N] iridium (acetylacetonate or 2-picolinic acid) were synthesized. 7-Dimesitylboryl (DMB) or 7-diphenylphosphoryl (DPPO) 9,9-diethylfluorenyl with larger steric hindrance was introduced into 2-phenyl-4-phenylquinoline or 5-trifluoromethylpyridine iridium complex to improve the electron-injection and electron-transport abilities and to decrease intermolecular interaction, which promoted luminous efficiency and adjusted emission. The devices displayed stable electroluminescent (EL) peaks at about 620, 600 and 584 nm, which exhibited approximate CIE coordinates of (0.67, 0.33), (0.62, 0.38) and (0.58, 0.42) with maximum current (external quantum) efficiencies of 9.1 (5.7 %), 13.2 (8.7 %) and 6.4 cd/A (3.5 %). Slow decay and high efficiency of devices showed the potential red or orange emitters.

Comparative investigation on carbon dots and chloride fluxes modified ZnAl2O4:Cr3+ nanophosphors for temperature sensing, cutting-edge forensic, anti-counterfeiting and w-LEDs applications

A novel Cr3+ doped ZnAl2O4 is synthesized by grafting carbon dots (CDs) and chloride fluxes (NaCl, KCl, NH4Cl) through the solid-state reaction method. Upon excitation at 530 nm wavelength, the Cr3+ ions in the ZAO NPs emit red light due to the influence of a strong crystal field. This red emission arises from the electric dipole 2Eg→4A2g of the Cr3+ ions. Among the chloride fluxes examined, NH4Cl had a significant impact on the PL intensity. Notably, when CDs are incorporated into the ZAO:7Cr3+/NH4Cl NPs, a remarkable increase of 17.25-folds in photoluminescence (PL) intensity is observed. This enhancement is substantially higher than that of CDs alone (11.23-folds) and NH4Cl alone (3.82-folds). The increased PL intensity is attributed to the Förster resonance energy transfer (FRET) mechanism. Furthermore, the addition of CDs (5 wt.%) enhanced the colour purity (CP) of ZAO:7Cr3+/NH4Cl NCs to 99.8%, achieving a high Internal quantum efficiency (IQE) of 93.4 %. Notably, the CDs (5 wt.%)@ZAO:7Cr3+/NH4Cl NCs maintained 92.43 % of their emission intensity even at 420 K, demonstrating exceptional thermal stability compared to ZAO:7Cr3+ NPs. Moreover, the NPs holds promise for optical thermometry, boasting a high relative sensitivity (Sr) of 6.74 × 10–2 %K-1 across a temperature range spanning from 300 to 480 K. Moreover, the latent fingerprints (LFPs) developed using CDs(5 wt.%)@ZAO:7Cr3+/NH4Cl NCs demonstrate remarkable selectivity and high contrast. Under UV irradiation, the structural features of LFPs at levels I–III are clearly visible. In addition, the strong red fluorescence emitted by CDs(5 wt.%)@ZAO:7Cr3+/NH4Cl NCs makes them suitable for applications in AC. CDs(5 wt.%)@ZAO:7Cr3+ NCs exhibit significant potential for w-LED fabrication, achieving a correlated colour temperature (CCT) of 5517 K, a CIE coordinate of (0.332, 0.331), and a high colour rendering index (CRI) of Ra = 94, outperforming ZAO:7Cr3+/NH4Cl NPs. Overall results clearly demonstrates that, CDs(5 wt.%)@ZAO:7Cr3+/NH4Cl NCs are effective for applications in optical thermometry, dactyloscopy, w-LEDs, and AC.

Thermally Activated Delayed Fluorescence Sensitizer with Through‐Space Charge Transfer Manipulated by Atom Distribution for Solution‐Processed Deep‐Blue Multi‐Resonance OLEDs

AbstractOrganic light‐emitting diodes (OLEDs) employing multi‐resonance (MR) emitters have attracted much attention due to their high luminescent efficiency and color purity, however, the development of deep‐blue multi‐resonance OLEDs is hindered by the lack of suitable sensitizers. Here a novel design strategy is reported for thermally activated delayed fluorescence sensitizer with high reverse intersystem crossing (kRISC) and radiative transition (kR) rate by regulating atom distribution of a spatially‐aligned carbazole donor/diphenylpyrimidine acceptor structure to manipulate through‐space charge transfer (CT) process. It is found that diphenylpyrimidine acceptor with 1,3‐position nitrogen atoms is un‐conjugated to bridging phenyl moiety by the conjugation node of pyrimidine, while the acceptor with 1,5‐position nitrogen atoms is conjugated to bridging phenyl through conjugation site, opening through‐bond CT pathway via bridging phenyl besides through‐space CT from spatial donor‐acceptor interactions. As a result, the sensitizer with 1,5‐position nitrogen atoms exhibits enhanced oscillator strength by 3.5 folds and accelerated kR of 3.57 × 107 s−1, while keeping high kRISC of 4.03 × 106 s−1 and high singlet (S1) state (2.88 eV). Solution‐processed OLEDs using the sensitizer and deep‐blue multi‐resonance emitter exhibit efficient narrowband electroluminescence with CIE coordinates of (0.14, 0.13) and EQEmax of 15.6%, representing the state‐of‐the‐art device performance for deep‐blue multi‐resonance OLEDs by solution process.

Color Tunable Three Terminal (3-T) Vertically Stacked Tandem Organic Electroluminescent Devices.

Traditional full-color displays typically use a pixel layout with three side-by-side subpixels emitting red (R), green (G), and blue (B) colors. However, this configuration limits the resolution especially in augmented reality (AR) and virtual reality (VR) applications. To address the issue of low pixel density in display technology, this study demonstrated vertically stacked three-terminal (3-T) bottom-emitting tandem OLEDs (sOLED). These OLEDs offer color tunability, facilitated by individually controlled colour units. This study demonstrates two combinations: G+B and R+G. Incorporating three generations of OLED's materials phosphorescent (R), thermally activated delayed fluorescence (TADF) (G), and hyperfluorescent (B). The OLEDs achieve maximum current efficiencies of approximately 11 cd/A, 52.4 cd/A, and 40.7 cd/A for R, G, and B, respectively, in their respective tandem configurations. A wide range of colors can be achieved by blending G+B and R+G color spectrum by adjusting the voltage of independent color unit. The optimal mix results in a fine cyan color with CIE coordinates (0.273,0.5) in G+B sOLED and a warm white with CIE coordinates (0.416,0.518)in R+G sOLED. This work demonstrate a better performing 3-T sOLED utilizing three different generations OLED materials, offering an individual control within a single pixel providing enhanced pixel density for display technology.

Fluorescent Tetraphenylethylene-Based Cerium Metal-Organic Frameworks for White-Light-Emitting Diodes.

Discovery of highly efficient and thermal stable phosphors is the focus of the studies in phosphor-converted white light-emitting diodes (LEDs). Herein, a tetraphenylethylene-based cerium metal-organic framework (SYNU-2) was synthesized and characterized. The intricate architecture of SYNU-2 shows an overall 3D → 3D 2-fold interpenetration framework. SYNU-2 exhibited good luminescence properties, and its latent fingerprint developer was prepared, which showed good fluorescence and stability under ultraviolet (UV) radiation. It is worth noting that a prototype WLED device can be designed using SYNU-2 and red phosphors (Ca,Sr)AlSiN3:Eu2+ with CIE coordinates of (0.33, 0.33) at an applied 3 V bias.

Innovative synthesis and forensic applications of bio-mediated SrO–MgO–In[formula omitted]O[formula omitted] nanocomposites with blue photoluminescence

The first of its kind Strontium oxide–Magnesium Oxide–Indium oxide (SMI) nanocomposites were synthesized utilizing a bio-mediated method with Euphorbiatirucalli latex as a reducing agent, followed by calcination. Synthesis of SMI NCs is confirmed by Bragg reflections of SrO, MgO, and In2O3, among them peaks belonging to In2O3 are observed to be prominent. The crystallite size, and other parameters like dislocation density, strain, structural factor, and crystallinity were estimated. Due to lower surface energy and the adhesion of particles with weak forces, morphology of the surface contains a larger degree of agglomeration. The direct energy band gap was determined to be 3.18 eV. Furthermore, the PL (photoluminescence) emission spectra, CIE, and CCT coordinates strongly indicate high-intensity emission in the region of blue color. Dusting of powder reveals latent fingerprints. Synthesized SMI nanocomposite exhibits highly-resolved patterns in the form of ridges used to analyze specific latent fingerprints with clarity. Thus, the recently synthesized nanocomposite may have been used in forensics, fluorescence labeling, and blue light emission.

Spectral characteristics and luminescence applications of Eu3+-activated fluorosilicate Na2MgGd2[SiO3]4F2

This work reports the luminescence spectra and application of novel Eu3+-doped Na2MgGd2[SiO3]4F2 phosphor. The X-ray powder diffraction confirmed the pure phase formation of the samples with the monoclinic space group P21/c (No:14). The phosphors demonstrated efficient red emission at 613 nm from the electric dipole transitions 5D0→7F2. The optimal doping concentration was found to be approximately 25 mol%. Na2MgGd2[SiO3]4F2:0.25Eu3+ exhibits a high quantum efficiency (QE) of 57 % with excellent thermal stability and pure chromaticity. Red- and the white light-emitting diode devices were packaged using InGaN chips and Na2MgGd2[SiO3]4F2:0.25Eu3+. The fabricated WLED has CIE coordinates of (x = 0.33, y = 0.34), which are very close to the white point in the National Television System Committee (x = 0.33, y = 0.33). The color rendering index (CRI, Ra) and correlated color temperature (CCT) of the WLED are 91 and 4400 K, respectively. The results show that as a red luminescent phosphor, it is a potential candidate for the preparation of near-UV/blue InGaN-based WLEDs.

TICT, and Deep-Blue Electroluminescence from Acceptor-Donor-Acceptor Molecules.

Donor-acceptor (D-A) materials based on butterfly-shaped molecules could inhibit exciton-migration-induced quenching due to molecular twist. To explore this attribute towards beneficial photophysical properties, three novel bipolar acceptor-donor-acceptor (A-D-A) molecules with triphenyl triazine end capping along with substitution ortho to the Tröger's base (TB) scaffold varying from H, Me, and F were explored. The installation of H/Me/F imparted an electron push-pull effect with concomitant maneuvering of photophysical properties. On increasing solvent polarity, a remarkable bathochromic shift with a significant decrease in emission efficiency was observed due to the twisted intramolecular charge transfer state (TICT). Emission enhancement in the ethylene glycol-water mixture and diminution in the THF-water mixture further confirmed the existence of TICT states in these TBs. The torsional dynamics in the excited state were also evidenced by the time-dependent density-functional theory (TD-DFT) calculations. Owing to the butterfly architecture of the TB that suppressed TICT, TB-Trzs exhibited a significant blue shift, accompanied by a favorable quantum yield in the solid state. Among the three compounds, Me-TB-Trz exhibited deep-blue photoluminescence and was explored as a dopant in organic light-emitting diodes (OLEDs) to obtain deep-blue electroluminescence of brightness 4128 cdm-2 and CIE coordinates of (0.16, 0.09).

Coordinative Polyimides‐Ln3+ for Full‐Spectrum Luminescence with Applications in PLEDs and Acid‐Responsive Data Encryption

AbstractControllable coordination and efficient sensitization of rare earth ions in polymer materials are key to achieving high‐performance optoelectronic polymers. By designing aromatic diamines, polyimides are synthesized with 1,10‐phenanthroline benzimidazole groups (PBG) in the polymer backbone. Utilizing the coordination between PBG and rare earth ions (Eu3⁺, Tb3⁺), polyimide‐rare earth complexes are formed and precisely characterized their structures. The unique coordination allows PBG to effectively sensitize Eu3⁺, resulting in efficient, long‐lived red emission. Furthermore, PBG maintains excellent coordination with Eu3⁺ in acidic environments, granting acid‐responsive color changes for data encryption. Importantly, PBG sensitization of Tb3⁺ enabled full‐spectrum emission (CIE coordinates: (0.31, 0.35)) within a single rare earth‐polyimide complex, due to electron transfer among the ions, ligands, and polymer. This leads to the design of a multi‐layer PLED device with an optimal external quantum efficiency of 0.43% for white light emission (CIE coordinates: (0.28, 0.34)). Through comparative theoretical and experimental analysis, the photophysical behavior of these coordinated polyimides is explained and explored their photoluminescent and electroluminescent properties. This research integrates the advantages of rare earth elements and polyimides, creating novel luminescent polymers with diverse optical applications, providing a new strategy for designing luminescent coordination polymers.

Versatile Molecular Structure Strategy Toward Highly Efficient Single‐Component White Organic Light–Emitting Diodes

AbstractLuminophores' dual emission (DE) properties hold great potential for realizing single‐component white organic light–emitting diodes (WOLEDs). This study illustrates that the unique and vibrant DE phenomena with different luminous mechanisms can be formed through simple modulation of molecular structures. Four target luminophores, namely 2‐TPE‐PPI, 2‐TPE‐PI, 2‐TPE‐An‐PPI, and 2‐TPE‐An‐PI, capable of DE under different conditions, are intentionally designed and successfully synthesized. Owing to the inherent flexibility of the minor molecular backbone and minor steric hindrance, 2‐TPE‐PPI and 2‐TPE‐PI exhibit DE spectra in dilute solutions with different solvent polarities. The intrinsic cause of the DE phenomenon in 2‐TPE‐An‐PPI and 2‐TPE‐An‐PI arises from the localized distribution of frontier molecular orbits resulting from the presence of an anthracene unit and the formation of an exciter group through intermolecular interactions involving anthracene. Remarkably, single‐emissive‐layer WOLEDs based on 2‐TPE‐An‐PPI and 2‐TPE‐An‐PI demonstrate stable white emission with CIE coordinates at (0.33, 0.39) and (0.30, 0.39), respectively, closely approaching the CIE coordinates of standard white light. Moreover, they maintain stable EL spectra from 4 to 10 V, an exceptional attribute rarely observed in many white light devices.

Combining SSVD and subsequent heat treatment processes to fabricate high-quality CsPbBr3 perovskite films

Perovskites, known for their excellent photoluminescence efficiency and color purity, have seen widespread application in flat panel displays and lighting in recent years. Here, we present a process for fabricating CsPbBr3 perovskite film (PeFilm) with high luminescent properties and remarkable weather resistance. By combining single-source vapor deposition (SSVD) with subsequent heat treatment, the quality of PeFilms has been significantly improved. We enhanced the quality of PeFilms by using a thermal annealing process to remove PbBr2 from CsPb2Br5. During annealing, PbBr2 evaporates from PeFilms, changing the crystal phase to CsPbBr3. The heat treatment rearranges atoms between grains, promoting grain growth and fusion, producing larger crystals and reducing defects. The research results demonstrate that the integration of SSVD and appropriate heat treatment enables the fabrication of the CsPbBr3 PeFilm with an emission wavelength of 533 nm, CIE coordinates of (0.1842, 0.7797), and a photoluminescence quantum yield (PLQY) of 52.1%, and even after storing it in atmospheric conditions for 100 days, the PLQY of the CsPbBr3 PeFilm remains above 52%, demonstrating excellent stability.