High Photoluminescence Quantum Yield Research Articles

Ultrasensitive Piezochromic Molecular Crystals: Mechanical Pressure‐Induced Controlled Regulation of TADF and RTP

AbstractConsidering that regulation of thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) is necessary for a fluorophore to survive and properly show its characteristic features, it is successfully shown herein that a carefully designed novel pyrene derivative can exhibit remarkable aggregation‐induced emission (AIE) overcoming the characteristic fast excitonic decay of pyrene compounds. Moreover, it is established that J‐aggregation in the red‐emitting molecular crystals of the compound reduces the singlet‐triplet energy gap (∆EST), allowing TADF with a very high photoluminescence quantum yield (PLQY) of 72%. Whereas, anisotropic grinding of the same crystals generates well‐defined microcrystals that show RTP as the nature of aggregation changes. Impressively, under isotropic hydrostatic pressure, the crystals show near‐infra‐red (NIR) emission with a very high piezochromic luminescence sensitivity of 46.2 nm GPa−1. The results have established that formation of stable H‐aggregates in the microcrystals is responsible for the ultra‐long RTP. A highly sophisticated full‐spectrum Mueller‐matrix analysis is used for the first time in such systems to demonstrate the details of the effect of perturbation (pressure) on molecular conformation.

Targeted synthesis of a 3D covalent organic framework with fjh topology exhibiting high photoluminescence: A robust platform for sensitive detection of furantoin

The inappropriate use of antibiotics poses significant risks to both the environment and human health, necessitating the development of accurate and sensitive detection methods. Fluorescence detection, particularly utilizing three-dimensional (3D) covalent organic frameworks (COFs), stands out as a promising avenue. Unlike two-dimensional COFs, 3D COFs can mitigate fluorescence quenching resulting from non-radiative energy loss, primarily attributed to π-π interlayer stacking. In this study, by carefully selecting and designing the building blocks, we synthesized a 3D COF named PyTTA-TTFB-COF with fjh topology and remarkable photoluminescence. This was achieved through the combination of a 4-connected square chromophore, 1,3,6,8-Tetrakis(4-aminophenyl) pyrene, with a 3-connected triangle, 1,3,5-trimethyl-2,4,6-tris(4-formylphenyl) benzene, possessing a specific stereo conformation. Significantly, PyTTA-TTFB-COF exhibits a high photoluminescence quantum yield, notably reaching 60.1% in acetonitrile. Moreover, it displays substantial fluorescence quenching when exposed to furantoin, surpassing the performance observed with other antibiotics. Competitive experiments have confirmed that PyTTA-TTFB-COF can serve as a specific fluorescent probe for the interference-free detection of furantoin.

Green‐Emissive Carbon Dots with a High Quantum Yield Applied for Photoconversion Film to Prevent from Blue Light Damage

AbstractHigh‐energy blue light is highly detrimental to health as it can penetrate the lens into the retina, potentially causing atrophy or even death of retinal pigment epithelial cells. To prevent the harmful effects of high‐energy blue light on our health, here the preparation of a photoconversion film specifically designed to block high‐energy blue light is reported, which is composed of green‐emissive carbon dots (G‐CDs) with a high photoluminescence quantum yield (PLQY = 95%) dispersed in polyvinyl alcohol (PVA) matrix. Notably, such a film (named as G‐CDs@PVA) not only converts an incident laser light with a short wavelength into a fluorescence with a longer wavelength, but also exhibits concentration‐dependent (0, 10, 20, and 30 wt.%) blue light barrier rate and green‐emissive intensity. With the increase of the concentration of G‐CDs in the film, the blue light barrier rate of the film as well as the maximum intensity of the green emission are also increased. When the concentration of G‐CDs reaches 30 wt.%, the blue light barrier rate of G‐CDs@PVA achieves up to 97%. Furthermore, G‐CDs@PVA film is attached to a blue light‐emitting diode (LED) chip to explore its practical application in the field of blocking blue light damage.

Modulating the Locally Excited States with a Regulating Substituent for Highly Efficient Red/Near‐Infrared Thermally Activated Delayed Fluorescence Emitters

AbstractDeveloping highly efficient red/near‐infrared (NIR) thermally activated delayed fluorescence (TADF) materials is important for organic light‐emitting diodes (OLEDs). Here, two TADF emitters, APTT and APTI, which have the same D/A backbone but different attaching groups at acenaphtho‐[1,2‐b]pyrazine‐8,9‐dicarbonitrile (APDC) core, are reported. The appended regulating groups can not only suppress the D/A rotation due to the space confinement effects but also modulate the locally excited triplet state (3LE). The improved molecular rigidity suppresses the non‐radiative process, accounting for the improved photoluminescence quantum yields (PLQYs), while the modulated 3LE promotes the reverse intersystem crossing (RISC) process due to the high utilization efficiency of triplets. Consequently, both APTT and APTI demonstrate high PLQY and fast RISC process, thereby enhancing TADF efficiency. The doped devices based on APTT and APTI achieve maximum external quantum efficiency (EQEmax) values of 20.5% and 25.4% with emission peaks at 664 and 670 nm, respectively. The non‐doped devices of APTT and APTI achieve the EQEmax of 2.8% and 2.9% with emission peaks at 788 and 794 nm, respectively. Encouragingly, the non‐doped devices of APTI have set new records for near‐infrared TADF OLEDs based on the APDC core. This study provides an efficient approach to modulating the optoelectronic properties of highly efficient NIR TADF OLEDs.

Synthesis, characterization, and optical studies of lead-free perovskite, Cs3M2Br9 (M = Bi, Sb) nanocrystals

In recent years, there has been a surge in research interest surrounding all inorganic lead perovskite nanocrystals (NCs) owing to their exceptional performance in various optoelectronic devices. Nevertheless, the presence of lead and concerns regarding its toxicity and stability have cast a shadow over their potential wide-ranging applications. In this study, we present the synthesis of two lead-free all-inorganic perovskite materials, Cs3M2Br9 (where M = Bi or Sb), in bulk form, using an aqueous halide acid medium. Additionally, we describe a top-down approach for the fabrication of two lead-free all-inorganic perovskite, Cs3M2Br9 (M = Bi or Sb) NCs. The Cs3Sb2Br9 NCs display a sheet-like morphology, while Cs3Bi2Br9 NCs exhibit a cubic structure. The PL spectra of Cs3Sb2Br9 and Cs3Bi2Br9 NCs exhibit distinct emission peaks at 476 nm and 472 nm, respectively, with relatively narrow full width at half maximum (FWHM) of 44 nm and 38 nm, respectively. Cs3Sb2Br9 and Cs3Bi2Br9 NCs demonstrate excellent thermal stability up to 320 °C and 470 °C, respectively. Notably, the high photoluminescence quantum yield (PLQY) of these NCs, Cs3Sb2Br9 NCs (31 %) and Cs3Bi2Br9 NCs (36 %) are highly beneficial for optoelectronic applications is observed.

From Dopant to Host: Solution Synthesis and Light‐Emitting Applications of Organic‐Inorganic Lanthanide‐Based Metal Halides

The rich and unique energy level structure arising from 4fn inner shell configuration of trivalent lanthanide ions (Ln3+) renders them highly attractive for light‐emitting applications. Currently, research primarily focuses on Ln3+ doping in either traditional garnets or the recently developed perovskite phosphors. However, there have been few reports on stable phosphors crystallized with pure lanthanide elements. Herein, a universal solution‐based route to eight Ln3+‐based metal halides from the organic‐inorganic A4LnX7 family is described, where A+ = 4,4‐difluoropiperidinium (DFPD+), Ln3+ = Nd3+, Eu3+, Ho3+, Sm3+, Tm3+, Tb3+, Yb3+, Er3+, and X− = Cl−, Br−. Visible photoluminescence (PL) is observed from Tb3+‐, Eu3+‐, Ho3+‐, and Sm3+‐based compounds with Tb and Eu compositions exhibiting high PL quantum yields of 90–100%; Nd3+‐, Tm3+‐, Yb3+‐, and Er3+‐based crystals show fascinating near‐infrared emission. Light‐emitting diodes (LEDs) fabricated with (DFPD)4TbCl7 yield characteristic emission of Tb3+, representing the first demonstration of electroluminescence from these organic‐inorganic Ln3+‐based metal halides. Moreover, these materials exhibit distinct excitation wavelength‐dependent emission after alloying with different Ln3+ ions, making them interesting for multicolor display and multilevel information encryption applications. It is foreseen that this study will open up the way to a possible design of robust optoelectronic devices based on lanthanide metal halides.

Ultrastable Copper Iodide Hybrid with Intrinsic Greenish White-Light Emission by Incorporating an Anionic Inorganic Functional Unit into an Extended Structure.

Incorporating a functional unit into the multidimensional coordination polymer skeleton is an efficient way to improve the stability of materials and expand their application. In this paper, anionic copper iodide inorganic functional modules are incorporated into one-dimensional extended chains by using a unique bidentate cationic organic ligand. Benefiting from the ionic extended structure, the resulting hybrid possesses a remarkable stability with a decomposition temperature as high as 300 °C. Meanwhile, the hybrid material exhibits intrinsic greenish white-light emission with a high photoluminescent quantum yield of 70%. The emission was investigated by temperature-dependent emission spectra, which proved to be the result of the synergistic effect of two energy states. The novel synthetic strategy provides an efficient route for the development of functional organic metal halides.

Mn Derived Growth of CsPbBr3 Nanoplatelets for Stable and Bright Orange Emission

Abstract Mn-doped perovskites have been extensively studied in optics, magnetism, and electronics due to their orange emission. However, successful Mn doping required a high Mn/Pb feed ratio. In this paper, Mn-doped CsPbBr3 nanoplatelets (NPLs) with bright orange emission were prepared by a two-step slow thermal injection synthesis. The slow injection of precursors effectively slow-down the crystal growth kinetic process and controls the growth of undoped CsPbBr3 NPLs. This process also significantly improves Mn doping efficiency. Mn doping induced the generation of numerous precursor clusters during the growth of CsPbBr3 NPLs, and the formation of these clusters was crucial for enhancing the doping efficiency. The maximum amount of Mn precursor in CsPb0.83Mn0.17Br3 was 50% of Pb precursors. The photoluminescence quantum yields (PLQYs) of CsPb0.94Mn0.06Br3 NPLs reached up to 80.6%, which was 3.1 times of that of CsPbBr3 NPLs. The PL properties of Mn-doped CsPbBr3 NPLs were significantly enhanced compared with pure CsPbBr3 NPLs. The growth process and luminescence mechanism of Mn-doped CsPbBr3 NPLs were discussed. High PLQYs and efficient Mn doping supplied an ideal approach for the preparation of various CsPbX3 (X = Cl, Br, and I) NCs for commercial applications.

Efficient Deep-Blue Multiple-Resonance Emitters Based on Azepine-Decorated Ν-DABNA for CIEy below 0.06.

Ultrapure deep-blue emitters are in high demand for organic light-emitting diodes (OLEDs). Although color coordinates serve as straightforward parameters for assessing color purity, precise control over the maximum wavelength and full-width at half-maximum is necessary to optimize OLED performance, including luminance efficiency and luminous efficacy. Multiple-resonance (MR) emitters are promising candidates for achieving ideal luminescence properties; consequently, a wide variety of MR frameworks have been developed. However, most of these emitters experience a wavelength displacement from the ideal color, which limits their practical applicability. Therefore, a molecular design that is compatible with MR emitters for modulating their energy levels and color output is particularly valuable. Here, we demonstrate that the azepine donor unit induces an appropriate blue-shift in the emission maximum while maintaining efficient MR characteristics, including high photoluminescence quantum yield, narrow emission, and a fast reverse intersystem crossing rate. OLEDs using newly developed MR emitters based on the ν-DABNA framework simultaneously exhibit a high quantum efficiency of ∼30%, luminous efficacy of ∼20lm W-1, exceptional color purity with Commission Internationale de l'Éclairage coordinates as low as (0.14, 0.06), and notably high operational stability. These results demonstrate unprecedentedly high levels compared with those observed in previously reported deep-blue emitters. This article is protected by copyright. All rights reserved.

The deposition and the optical characteristics of Cu-based metal halide Cs3Cu2I5 thin film via mist deposition

Abstract Cu-based metal halides, such as Cs3Cu2I5, are promising materials for light-emitting diodes, photodetectors, and scintillators because of their excellent optical properties, nontoxicity, and high air stability. In this study, we demonstrated the deposition of high-coverage Cs3Cu2I5 thin films using solution-based mist deposition. By adjusting the substrate temperature appropriately, continuous Cs3Cu2I5 thin films were formed. The Cs3Cu2I5 thin films exhibited blue emission under ultraviolet irradiation, with a large Stokes shift of 1.40 eV. Furthermore, they exhibited a high photoluminescence quantum yield of over 80%.

Elimination of Intragrain Defect to Enhance the Performance of FAPbI3 Perovskite Solar Cells by Ionic Liquid.

Ionic liquids have been widely used to improve the efficiency and stability of perovskite solar cells (PSCs), and are generally believed to passivate defects on the grain boundaries of perovskites. However, few studies have focused on the relevant effects of ionic liquids on intragrain defects in perovskites which have been shown to be critical for the performance of PSCs. In this work, the effect of ionic liquid 1-hexyl-3-methylimidazolium iodide (HMII) on intragrain defects of formamidinium lead iodide (FAPbI3) perovskite is investigated. Abundant {111}c intragrain planar defects in pure FAPbI3 grains are found to be significantly reduced by the addition of the ionic liquid HMII, shown by using ultra-low-dose selected area electron diffraction. As a result, longer charge carrier lifetimes, higher photoluminescence quantum yield, better charge carrier transport properties, lower Urbach energy, and current-voltage hysteresis are achieved, and the champion power conversion efficiency of 24.09% is demonstrated. These observations suggest that ionic liquids significantly improve device performance resulting from the elimination of {111}c intragrain planar defects.

Purely Organic Room‐Temperature Phosphorescence Molecule for High‐Performance Non‐Doped Organic Light‐Emitting Diodes

Purely organic molecules with room‐temperature phosphorescence (RTP) are potential luminescent materials with high exciton utilization for organic light‐emitting diodes (OLEDs), but those exhibiting superb electroluminescence (EL) performances are rarely explored, mainly due to their long phosphorescence lifetimes. Herein, a robust purely organic RTP molecule, 3,6‐bis(5‐phenylindolo[3,2‐a]carbazol‐12(5H)‐yl)‐xanthen‐9‐one (3,2‐PIC‐XT), is developed. The neat film of 3,2‐PIC‐XT shows strong green RTP with a very short lifetime (2.9 μs) and a high photoluminescence quantum yield (72%), and behaviors balanced bipolar charge transport. The RTP nature of 3,2‐PIC‐XT is validated by steady‐state and transient absorption and emission spectroscopies, and the working mechanism is deciphered by theoretical simulation. Non‐doped multilayer OLEDs using thin neat films of 3,2‐PIC‐XT furnish an outstanding external quantum efficiency (EQE) of 24.91% with an extremely low roll‐off (1.6%) at 1000 cd m‒2. High‐performance non‐doped top‐emitting and tandem OLEDs are also achieved, providing remarkable EQEs of 24.53% and 42.50%, respectively. Delightfully, non‐doped simplified OLEDs employing thick neat films of 3,2‐PIC‐XT are also realized, furnishing an excellent EQE of 17.79% and greatly enhanced operational lifetime. The temperature‐dependent and transient EL spectroscopies demonstrate the electrophosphorescence attribute of 3,2‐PIC‐XT. These non‐doped OLEDs are the best devices based on purely organic RTP materials reported so far.

Purely Organic Room-Temperature Phosphorescence Molecule for High-Performance Non-Doped Organic Light-Emitting Diodes.

Purely organic molecules with room-temperature phosphorescence (RTP) are potential luminescent materials with high exciton utilization for organic light-emitting diodes (OLEDs), but those exhibiting superb electroluminescence (EL) performances are rarely explored, mainly due to their long phosphorescence lifetimes. Herein, a robust purely organic RTP molecule, 3,6-bis(5-phenylindolo[3,2-a]carbazol-12(5H)-yl)-xanthen-9-one (3,2-PIC-XT), is developed. The neat film of 3,2-PIC-XT shows strong green RTP with a very short lifetime (2.9 μs) and a high photoluminescence quantum yield (72%), and behaviors balanced bipolar charge transport. The RTP nature of 3,2-PIC-XT is validated by steady-state and transient absorption and emission spectroscopies, and the working mechanism is deciphered by theoretical simulation. Non-doped multilayer OLEDs using thin neat films of 3,2-PIC-XT furnish an outstanding external quantum efficiency (EQE) of 24.91% with an extremely low roll-off (1.6%) at 1000 cd m‒2. High-performance non-doped top-emitting and tandem OLEDs are also achieved, providing remarkable EQEs of 24.53% and 42.50%, respectively. Delightfully, non-doped simplified OLEDs employing thick neat films of 3,2-PIC-XT are also realized, furnishing an excellent EQE of 17.79% and greatly enhanced operational lifetime. The temperature-dependent and transient EL spectroscopies demonstrate the electrophosphorescence attribute of 3,2-PIC-XT. These non-doped OLEDs are the best devices based on purely organic RTP materials reported so far.

Stretchable Metal Halide Perovskite Color Conversion Layers with Block Copolymer Dispersant

AbstractStretchable luminescent nanocomposites with metal halide perovskite (MHP) emitters are in high demand as deformable color‐conversion layers (CCLs) for vivid‐colored form‐factor free displays. However, the immiscibility of the MHP crystals with an elastomeric polymer matrix induces particle aggregation with resultant luminescence quenching, hindering the development of MHP‐based CCLs. Herein, a simple method is proposed to produce highly luminescent MHP nanoparticles (NPs) and stably disperse them in an elastomeric poly(dimethylsiloxane) (PDMS) polymer matrix with block copolymer (BCP) dispersant. The nanocomposites are developed through sequential steps of synthesis of MHP‐NP dispersion solution with BCP and blending with PDMS followed by thermal curing. It is revealed that Lewis basic poly(2‐vinylpyridine)‐block‐poly(dimethylsiloxane) (P2VP‐b‐PDMS) BCP added in the synthesis step promotes crystallization of the MHPs as nanocrystals with an average diameter of 5.9 ± 1.2 nm, whereas MHPs with hundreds of nm are produced without BCP. The resultant MHP‐NPs with P2VP‐b‐PDMS exhibit excellent photophysical properties, such as narrow band emission, high photoluminescence (PL) quantum yield, and long PL lifetime. The MHP‐NPs are stably dispersed in the PDMS matrix by P2VP‐b‐PDMS without particle aggregation, leading to highly deformable and stretchable nanocomposites with stable PL emission upon repetitive stretching, and excellent environmental stability.

Ir(III) Metal Emitters with Cyano-Modified Imidazo[4,5-b]pyridin-2-ylidene Chelates for Deep-Blue Organic Light-Emitting Diodes.

Ir(III) carbene complexes have been explored as one of the best blue phosphors for their high performance. Herein, the authors designed and synthesized a series of blue-emitting Ir(III) phosphors (f-ct9a-c), featuring fac-coordinated cyano-imidazo[4,5-b]pyridin-2-ylidene cyclometalates. These Ir(III) complexes exhibit true-blue emission with a peak maximum spanning 448-467 nm, with high photoluminescence quantum yields of 81-88% recorded in degassed toluene. Moreover, OLED devices bearing phosphors f-ct9a and f-ct9b deliver maximum external quantum efficiencies (EQEmax) of 25.9% and 30.3%, together with Commission Internationale de L'Eclairage (CIEx,y) coordinates of (0.157, 0.225) and (0.142, 0.169), respectively. Remarkably, the f-ct9b-based device displays an incredible EQE of 29.0% at 5000 cd·m-2. The hyper-OLED device based on f-ct9b and ν-DABNA exhibits an EQEmax of 34.7% and CIEx,y coordinates of (0.122, 0.131), affirming high potentials in achieving efficient blue electroluminescence.

Modulation of Nucleation and Growth Kinetics of Perovskite Nanocrystals Enables Efficient and Spectrally Stable Pure-Red Light-Emitting Diodes.

Perovskite light-emitting diodes (PeLEDs) based on CsPb(Br/I)3 nanocrystals (NCs) usually suffer from severe spectral instability under operating voltage due to the poor-quality PeNCs. Herein, zeolite was utilized to prepare high-quality CsPb(Br/I)3 NCs via promoting the homogeneous nucleation and growth and suppressing the Ostwald ripening of PeNCs. In addition, the decomposed zeolite interacted strongly with PeNCs through Pb-O bonds and hydrogen bonds, which inhibited the formation of defects and suppressed halide ion migration, leading to an improved photoluminescence quantum yield (PLQY) and enhanced stability of PeNCs. Moreover, the strong binding affinity of decomposed zeolite to PeNCs contributed to the formation of homogeneous perovskite films with high PLQY. As a result, pure-red PeLEDs with Commission International de I'Eclairage (CIE) coordinates of (0.705, 0.291) were fabricated, approaching the Rec. 2020 red primary color. The devices achieved a peak external quantum efficiency of 23.0% and outstanding spectral stability.

Multifunctional Deep-Blue Thermally Activated Delayed Fluorescence Based on an Oxygen-Bridged Boron Acceptor for Highly Efficient Organic Light-Emitting Diodes.

Until now, thermally activated delayed fluorescence (TADF) materials based on bridged boron-based acceptors have been primarily developed as dopants. However, in this study, we synthesized and characterized multifunctional deep-blue TADF materials─t-OBO-DMAC and t-OBO-DPAC─using bridged boron-based acceptors in combination with dimethylacridine or diphenylacridine as donors. These materials serve as both dopants and hosts. Theoretical calculations and experimentally measured photophysical properties of t-OBO-DMAC reveal a smaller singlet-triplet energy difference, higher photoluminescence quantum yield, and more efficient reverse intersystem crossing compared to t-OBO-DPAC. When evaluated as TADF emitters, t-OBO-DMAC and t-OBO-DPAC exhibited maximum external quantum efficiency (EQE) of 14.4 and 7.3% with deep-blue color coordinates of (0.14, 0.11) and (0.15, 0.07), respectively. Both materials were further assessed as hosts in various configurations, including host-only, TADF, phosphorescent, and phosphor-sensitized fluorescence (PSF)-emitting systems. Notably, t-OBO-DMAC demonstrated a high maximum EQE of 13.9% with deep-blue color coordinates of (0.15, 0.07) in a nondoped host-only device. Remarkably, both materials achieved EQEs exceeding 20% in the PSF devices. Our study marks a critical advancement in the field that breaks the conventional boundaries of the dopant and host and demonstrates unprecedented multifunctionalities for advanced organic light-emitting diodes.

A Novel Carbazolophane: A Comparison of the Performance of Two Planar Chiral CP‐TADF Emitters

AbstractThe prototypical example of a (cyclo)phane, [2.2]paracyclophane (PCP), has proven to be a versatile stereogenic moiety within the design of circularly polarized thermally activated delayed fluorescence (CP‐TADF) emitters; however, the exploration of other cyclophanes within CP‐TADF emitter design has been largely neglected. Here, a comparative study of the photophysical and optoelectronic properties of two cyclophane emitters, (1,7)tBuCzpPhTrz and its isomer (1,4)tBuCzpPhTrz, is presented. The carbazolophane‐triazine compound (1,7)tBuCzpPhTrz, obtained via an unprecedented intramolecular rearrangement, is the first example of a planar chiral TADF emitter deviating from the PCP scaffold. Significant geometrical change of the enclosed carbazole in (1,7)tBuCzp results in an attenuation of the donor strength, while the merits of rigidity and steric bulk remain. In particular, the full width at half maximum (FWHM) of the photoluminescence spectrum in toluene of (1,7)tBuCzpPhTrz is reduced by 34% and blue‐shifted by 20 nm compared to that of (1,4)tBuCzpPhTrz. In doped films, the compounds reach high photoluminescence quantum yields (ΦPL) of 91 and 81%, respectively. The chiroptical properties reveal dissymmetry factors |gPL| of up to 5 × 10−4. These results demonstrate the impact of the cyclophane for the development of CP‐TADF materials and add to the currently limited scope of available planar chiral donors.

A 4.7‐inch 650 PPI AMQLED display prepared by direct photolithography

AbstractIn this work, a highly efficient photosensitive quantum dot (QD) system was designed. The optimized photosensitive QD system had high photoluminescence quantum yield and colloidal stability. By direct photolithography, RGB pixel arrays with a single sub‐pixel size of 39 μm × 5 μm were successfully prepared. Further, the full‐color QLED device was realized. There were no residual QD emission peaks from neighboring sub‐pixels observed in the electroluminescence spectra. Experience on the full‐color QLED device guided the successful preparation of a 4.7‐inch 650 PPI active matrix QLED prototype. The active matrix QLED prototype could display clear and complete pictures. The color gamut reached 85% of the BT2020 standard. This is the first active matrix QLED prototype prepared with a record‐high resolution by direct photolithography, which promoted the development of QLED display technology.

High-Efficiency and Stable Colloidal One-Dimensional Core/Shell Nanorod Light-Emitting Diodes.

Anisotropic nanocrystals such as nanorods (NRs) display unique linearly polarized emission, which is expected to break the external quantum efficiency (EQE) limit of quantum dot-based light-emitting diodes (LEDs). However, the progress in achieving a higher EQE using NRs encounters several challenges, primarily involving a low photoluminescence quantum yield (PLQY) of NRs and imbalanced charge injection in NR-LEDs. In this work, we investigated NR-LEDs based on CdSe/CdZnS/ZnS rod-in-rod NRs with a high PLQY and higher linear polarization compared to those of dot-in-rod NRs. The balanced charge injection is achieved using ZnMgO nanoparticles as the electron transport layer and poly-TPD {poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine]} as the hole transport layer. Therefore, the NR-LEDs exhibit a maximum EQE of 21.5% and a maximum luminance of >120 000 cd/m2 owing to the high level of in-plane transitions with a dipole moment of 90%. The NR-LEDs also have greatly inhibited droop in EQE under a high current density as well as outstanding operation lifetime and cycle stability.