Stable Electroluminescence Research Articles

Inhibiting ion migration in strontium-lead halide perovskite for pure-blue emission: a first-principle and experimental study.

Bromide-chloride mixed perovskites have garnered significant attention as a direct and efficient material for achieving pure-blue emission. However, the complex problem of halide migration in mixed halide perovskites presents a significant obstacle to achieving stable electroluminescence (EL) spectra. Here, we investigate the mechanism of partially replacing the B-site Pb2+ with the non-toxic Sr2+ to achieve pure-blue emission based on first principles. The ion mobility activation energy of Sr2+ is 1.23 eV, which is an order of magnitude greater than that of halogens. Meanwhile, the incorporation of Sr2+ triples the activation energy for halogen migration. Furthermore, the halide defect formation energy increases from 4.75 eV to 5.62 eV, thereby reducing ion migration channels. Transient absorption spectroscopy demonstrates that suppressing the ion mobility pathway and enhancing ion mobility activation energy promotes the perovskite film to exhibit excellent spectral stability under laser pumping. Our work provides insights for the development of highly stable and eco-friendly perovskite devices.

Vacuum evaporation deposited RbxCs1-xPbBr3 thin films for spectrally tunable and stable all-inorganic blue light-emitting diodes

Perovskite light emitting diodes (PeLEDs) have emerged as a promising technology for new display applications due to their high color purity and precisely adjustable band gap. However, compared to green and red PeLEDs, blue PeLEDs suffer from lower luminous efficiency and stability. Traditionally, pure blue perovskite luminescence is achieved using mixed halogens, which often leads to phase separation issues. In this paper, we directly introduced RbBr and prepared RbxCs1-xPbBr3 (x = 0.5,0.6,0.7) thin films using thermal evaporation, achieving wavelength-tunable and stable blue light emission ranging from 477 nm to 489 nm.This is the first report of using thermal evaporation for the fabrication of RbxCs1-xPbBr3 films. PeLEDs based on these films exhibited stable electroluminescence under varying driving voltages. Operated continuously over 30 min at 6 V in ambient air with 36 % humidity, these devices showed superior spectral stability. Using pure bromine-based material RbxCs1-xPbBr3 (x = 0.5,0.6,0.7) in the light-emitting layer solves the problem of phase separation of mixed halogens and achieves blue-light emission. Additionally, the introduction of Rb+ distorts the crystal structure of perovskite. This distortion decreases the bond length of Pb-Br bonds, increases the bond energy, and raises the formation energy of halogen anion vacancies. As a result, the density of perovskite defect states decreases, and thus the stability is enhanced. This work represents a rare example of vacuum thermal-evaporation processed RbxCs1-xPbBr3 films and all-inorganic perovskite LEDs.

Solution Processed Bilayer Metal Halide White Light Emitting Diodes.

Metal halide perovskites and perovskite-related organic metal halide hybrids (OMHHs) have recently emerged as a new class of luminescent materials for light emitting diodes (LEDs), owing to their unique and remarkable properties, including near-unity photoluminescence quantum efficiencies, highly tunable emission colors, and low temperature solution processing. While substantial progress has been made in developing monochromatic LEDs with electroluminescence across blue, green, red, and near-infrared regions, achieving highly efficient and stable white electroluminescence from a single LED remains a challenging and under-explored area. Here, a facile approach to generating white electroluminescence is reported by combining narrow sky-blue emission from metal halide perovskites and broadband orange/red emission from zero-dimensional (0D) OMHHs. For the proof of concept, utilizing TPPcarz+ passivated two-dimensional (2D) CsPbBr3 nanoplatelets (NPLs) as sky blue emitter and 0D TPPcarzSbBr4 as orange/red emitter (TPPcarz+ = triphenyl (9-phenyl-9H-carbazol-3-yl) phosphonium), white LEDs (WLEDs) with a solution processed bilayer structure have been fabricated to exhibit a peak external quantum efficiency (EQE) of 4.8% and luminance of 1507 cd m-2 at the Commission Internationale de L'Eclairage (CIE) coordinate of (0.32, 0.35). This work opens a new pathway for creating highly efficient and stable WLEDs using metal halide perovskites and related materials.

Hole-Induced Degradation of ZnMgO and Insights into the Causes of the Limited Electroluminescence Stability of Blue Quantum Dot Light-Emitting Devices

Hole-Induced Degradation of ZnMgO and Insights into the Causes of the Limited Electroluminescence Stability of Blue Quantum Dot Light-Emitting Devices

Efficient and Stable Blue Perovskite Light‐Emitting Diodes Enabled by Effective Hydrolysis of Dichloride

AbstractDespite the substantial progress in sky‐blue (480−495 nm) perovskite light‐emitting diodes (PeLEDs), the pure‐blue PeLEDs (<480 nm) merely show moderate performances. As a straightforward and effective facile way to obtain pure‐blue emission, the bromide‐chloride mixed perovskites have received considerable attention. However, the tricky issue of halide migration in the mixed halide perovskites makes a tough challenge to achieve efficient PeLEDs with stable electroluminescence (EL) spectra. Herein, the in situ treatment of Cl‐rich benzene phosphorus oxydichloride (BPOD) is proposed to achieve high‐quality pure‐blue perovskites by simultaneously enlarging the perovskite bandgap, passivating the halide vacancy defects, and immobilizing the halide ions through the hydrolysis products of chloride ions and phenylphosphonic acid. As a result, highly‐performed pure‐blue PeLEDs with a maximum external quantum efficiency (EQE) of 9.3% at 477 nm, an impressive lifetime of 34.7 min at 104 cd m−2, and very stable EL spectra are achieved, which are superior to the conventional mixed halide PeLEDs based on lead‐chloride precursor, representing one of the best performances for mixed halide pure‐blue PeLEDs. Therefore, this work contributes a feasible and effective method for efficient and stable pure‐blue PeLEDs.

Intrinsically stretchable fully π-conjugated polymer film via fluid conjugated molecular external-plasticizing for flexible light-emitting diodes

Fully π-conjugated polymers with rigid aromatic units are promising for flexible optoelectronic devices, but their inherent brittleness poses a challenge for achieving high-performance, intrinsically stretchable fully π-conjugated polymer. Here, we are establishing an external-plasticizing strategy using semiconductor fluid plasticizers (Z1 and Z2) to enhance the optoelectronic, morphological, and stretchable properties of fully π-conjugated polymer films for flexible light-emitting diodes. The synergistic effect of hierarchical structure and optoelectronic properties of Z1 in poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT) films enable excellent stretchable deformability (~25%) and good conductivity. PLEDs based on F8BT/Z1 films show stable electroluminescence and efficiency under 15% stretch and 100 cycles at 10% strain, revealing outstanding stress tolerance. This strategy is also improving the stretchable properties of polymers like poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) and poly(2-methoxy-5(2′-ethyl)hexoxy-phenylenevinylene) (Super Yellow), demonstrating its general applicability. Therefore, this strategy can provide effective guidance for designing high-performance stretchable fully π-conjugated polymers films for flexible electronic devices.

Localized Electron Density Engineering for Bright and Stable Near-Infrared Electroluminescence from All-Inorganic Lead-Free Tin Halides

Localized Electron Density Engineering for Bright and Stable Near-Infrared Electroluminescence from All-Inorganic Lead-Free Tin Halides

Short-Wave Infrared Light-Emitting Diodes Using Colloidal CuInS2 Quantum Dots with ZnI2 Dual-Passivation.

Short-wave infrared (SWIR) light-emitting diodes (LEDs) have emerged as promising technologies for diverse applications such as optical communication, biomedical imaging, surveillance, and machine vision. Colloidal quantum dots (QDs) are particularly attractive for SWIR LEDs due to their solution processability, compatibility with flexible substrates, and tunable absorption and luminescence. However, the presence of toxic elements or precious metals in most SWIR-emitting QDs poses health, environmental, and cost challenges. In this context, CuInS2 (CIS) QDs are known for low toxicity, cost-effective fabrication, and SWIR-light emitting capability. However, CIS QDs have not yet been directly utilized to fabricate SWIR LEDs to date, which is due to low particle stability, inefficient charge carrier recombination, and significantly blue-shifted luminescence after integrating into LED devices. To address challenges, we propose a dual-passivation strategy using ZnI2 as a chemical additive to enhance both the optical property of plain CIS QDs and charge carrier recombination upon LED device implementation. The resulting CIS-QD-based LEDs exhibit a stable SWIR electroluminescence (EL) peak (over 1000 nm) with a high EL radiance and a record external quantum efficiency in the SWIR region. Our study represents a significant step forward in SWIR-QLED technology, offering a pathway for the development of high-performance, low-cost, and nontoxic SWIR light sources.

Patterned flexible Silver Nanowire/2D MXene transparent conducting electrode for organic light-emitting diodes

With the advent of numerous flexible optoelectronic applications, the importance of flexible and stable transparent conducting electrodes (TCEs) has been considerable. The conventional silver nanowire (AgNW) is a promising candidate as TCEs due to its decent opto-electrical properties and solution processibility. However, AgNW's high surface root mean square (RMS) roughness, relatively high sheet resistance, and low work function (∼4.5 eV) limit the usage for display applications. In this work, we design and study the AgNW and MXene (Ti3C2Tx) hybrid TCEs for flexible organic light-emitting diodes (OLEDs) to enhance the optoelectrical properties and the hole injection within the device. Experiment investigation is carried out via an application of AgNW/MXene (AgMX) hybrid TCEs as a bottom electrode for OLEDs devices in which the photolithography process and lift-off technique are employed for such fabrication. The hybrid TCEs indicate high optical transparency (86.8 % at 550 nm) and low sheet resistance (24.1 Ω/cm2) as well as improved surface morphology, enabling the efficient OLEDs operation. The optimized OLEDs exhibit a clear and stable red electroluminescence (EL) peak with an improved maximum external quantum efficiency (EQE) and luminance of 5.25 % and 3421.7 cd/m2, respectively. Furthermore, the hybrid TCEs are readily formed on poly(ethylene terephthalate) (PET) substrate, showing high durability under the bending test up to 100,000 cycles. The results demonstrate that adopting AgMX TCEs is a reasonable strategy for obtaining proper flexible optoelectronic devices.

(Invited) Next-Generation Photonic Source Based on Lateral GaAs/AlgaAs Heterostructure Devices

Quantum communications and remote sensing protocols rely on preparing individual quanta of light, or photons, as carriers of quantum information. While it is easy to generate many-photon classical states of light (e.g., a light bulb or a laser), it is challenging to generate single quanta or pairs of entangled quanta on-demand. Yet, only in this latter regime can the fundamentally quantum nature of light be exploited to achieve performance exceeding classical bounds.We are developing a single-photon source based on combining a one-parameter single electron pump (Figure 1a,b) – an electrically controlled, on-demand, high-fidelity emitter of single electrons [1] – with a lateral p-n junction [2] (Figure 1c,d) in which injected single electrons recombine with holes to produce single photons. These devices are realized in undoped GaAs/AlGaAs heterostructures and designed to be ambipolar. Such a quantum light source could lead to a paradigm shift in metrology, providing a quantum redefinition of two of the seven SI base units, the ampere and the candela. It is also possible in principle to realize scalable source arrays on a single chip. I will discuss progress towards realizing and characterizing these sources, including work on optimizing collection efficiency and Purcell enhancement using a lateral distributed Bragg reflector in a concentric ring geometry. Beyond fundamental studies, the proposed photon source will find practical use in quantum communications protocols (QKD), where it can offer fast data transmission rates, and quantum sensing with LiDAR, where it could outperform laser-based systems in the few-photon regime for low-power, stealth applications.[1] B. Buonacorsi et al, “Non-adiabatic single-electron pumps in a dopant-free GaAs/AlGaAs 2DEG”, Appl. Phys. Lett. 119, 114001 (2021).[2] L. Tian et al, “Stable electroluminescence in ambipolar dopant-free lateral p-n junctions”, Appl. Phys. Lett. 123, 061102 (2023). Figure 1

Reduction reactions at the interface between CdS quantum dot and Z-type ligands driven by electron injection in the electroluminescent processes.

The efficient and stable electroluminescence of quantum dots (QDs) is of great importance in their applications in new display technologies. The short service life of blue QDs, however, hinders their development and commercialization. Different mechanisms have been proposed for the destabilization of QDs in electroluminescent processes. Based on real-time time-dependent density functional theory studies on the QD models covered by Z-type ligands (XAc2, X = Cd, Zn, Mg), the structural evolution is simulated to reveal the mechanism of the reduction reactions induced by electron injection. Our simulations reproduce the experimental observations that the reduction reactions occur at the QD-ligand interface, and the reduced Cd atom is almost in a zero valence state. However, different sites are predicted for the reactions in which the surface metal atom of the QD instead of the metal atom in the ligands is reduced. As a result, one of the arms of the chelate ligand leaves the QD, which tends to cause damage to its electroluminescent performance. Our findings contribute to a mechanistic understanding of the reduction reactions that occurred at the QD-ligand interface.

Highly Horizontal Oriented Tricomponent Exciplex Host with Multiple Reverse Intersystem Crossing Channels for High-Performance Narrowband Electroluminescence and Eye-Protection White Organic Light-Emitting Diodes.

Despite multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters with small full-width at half maximum are attractive for wide color-gamut display and eye-protection lighting applications, their inefficient reverse intersystem crossing (RISC) process and long exciton lifetime induce serious efficiency roll-off, which significantly limits their development. Herein, a novel device concept of building highly efficient tricomponent exciplex with multiple RISC channels is proposed to realize reduced exciton quenching and enhanced upconversion of nonradiative triplet excitons, and subsequently used as a host for high-performance MR-TADF organic light-emitting diodes (OLEDs). Compared with traditional binary exciplex, the tricomponent exciplex exhibits obviously improved photoluminescence quantum yield, emitting dipole orientation and RISC rate constant, and a record-breaking external quantum efficiency (EQE) of 30.4% is achieved for tricomponent exciplex p-PhBCzPh: PO-T2T: DspiroAc-TRZ (50: 20: 30) based OLED. Remarkably, maximum EQEs of 36.2% and 40.3% and ultralow efficiency roll-off with EQEs of 26.1% and 30.0% at 1000cd m-2 are respectively achieved for its sky-blue and pure-green MR-TADF doped OLEDs. Additionally, the blue emission unit hosted by tricomponent exciplex is combined with an orange-red TADF emission unit to achieve a double-emission-layer blue-hazard-free warm white OLED with an EQEmax of 30.3% and stable electroluminescence spectra over a wide brightness range.

"Core-Shell" Wave Function Modulation in Organic Narrowband Emitters.

Efficient red-green-blue primary luminescence with an extraordinarily narrow band and durability is crucial for advanced display applications. Recently, the emergence of multiple-resonance (MR) from short-range atomic interactions has been shown to induce extremely narrow spectral widths in pure organic emitters. However, achieving wide-range color tuning without compromising color purity remains a persistent challenge for MR emitters. Herein, the concept of electronic donor/acceptor "core-shell" modulation is proposed within a boron/nitrogen (B/N) MR skeleton, enabling the rational utilization of intramolecular charge transfer to facilitate wavelength shift. The dense B atoms localized at the center of the molecule effectively compress the electron density and stabilize the lowest unoccupied molecular orbital wave function. This electron-withdrawing core is embedded with peripheral electron-donating atoms. Consequently, doping a single B atom into a deep-blue MR framework led to a profound bathochromic shift from 447 to 624 nm (∼0.8 eV) while maintaining a narrow spectral width of 0.10 eV in this pure-red emitter. Notably, organic light-emitting diodes assisted by thermally activated delayed fluorescence molecules achieved superb electroluminescent stability, with an LT99 (99% of the initial luminance) exceeding 400 h at an initial luminance of 1000 cd m-2, approaching commercial-level performance without the assistance of phosphors.

Strategic Buried Defect Passivation of Perovskite Emitting Layers by Guanidinium Chloride for High-Performance Pure Blue Perovskite Light Emitting Diodes.

Perovskite light-emitting diodes (PeLEDs) show promise for high-definition displays due to their exceptional electroluminescent properties. However, the performance of pure blue PeLEDs is hindered by the unfavorable ionic behavior of halides and the presence of defective antisites in blue-emitting perovskite materials. An unstable buried interface between charge transport layers and the perovskite emitting layer is a major issue that limits carrier transport and recombination behavior in PeLEDs. In this study, effective buried defect passivation of pure blue perovskite emitting layers by introducing guanidinium chloride (GACl) as a bottom-passivating layer is demonstrated. The GACl bottom layer not only passivates the point defects present at the buried interface but also provides chloride anions to suppress ion migration and halide vacancy formation. Along with the defect passivation, GACl also enforces phase purity of 2D layered structure in the perovskite emitting layers to improve crystallinity and optoelectronic properties. As a result, the PeLEDs with high brightness (1200cd m-2) and excellent external quantum efficiency (6.61%) are achieved at a spectrally stable pure blue electroluminescence at 471nm (band width = 17.63nm). This study offers insights into the straightforward way for effective buried passivation for preparing high-performance PeLEDs.

High Efficiency and Low Roll-Off Pure-Red Perovskite LED Enabled by Simultaneously Inhibiting Auger and Trap Recombination of Quantum Dots.

CsPbI3 perovskite quantum dots (QDs) could achieve pure-red emission by reducing their size, but the increased exciton binding energy (EB) and surface defects for the small-sized QDs (SQDs) cause severe Auger and trap recombinations, thus worsening their electroluminescence (EL) performance. Herein, we utilize the dangling bonds of the SQDs as a driving force to accelerate KI dissolution to solve its low solubility in nonpolar solvents, thereby allowing K+ and I- to bond to the surface of SQDs. The EB of the SQDs was decreased from 305 to 51 meV because of the attraction of K+ to electrons, meanwhile surface vacancies were passivated by K+ and I-. The Auger and trap recombinations were simultaneously suppressed by this difunctional ligand. The SQD-based light-emitting diode showed a stable pure-red EL peak of 639 nm, an external quantum efficiency of 25.1% with low roll-off, and a brightness of 5934 cd m-2.

Alloy Perovskite via Dual‐Functional Additive Engineering for Efficient Deep Blue Light‐Emitting Diodes

AbstractMixed halide perovskites are widely investigated as emitters for efficient light‐emitting diodes owing to their excellent optoelectronic properties. Compared with red and green emissions, encouraging progress in efficiency for blue emission has only been achieved in sky‐blue region. A high Cl/Br ratio is indispensable to achieve deep‐blue emission, which often leads to pronounced halogen migration in perovskite light‐emitting diodes (PeLEDs) and thus diminished efficacy. To avoid the negative effects of excessive chloride necessary to achieve deep‐blue emission, alloyed perovskite quantum dotes (QDs) passivated by dual‐functional guanidine sulfamate are synthesized, where S═O of sulfamate coordinates with Pb, and guanidine can form N‐H‐X (Cl/Br) with halogen ions to complete passivation. As a result, deep‐blue emission is achieved for the alloyed perovskite QDs. Owing to the suppressed defects and the reduced surface electrostatic potential of the perovskite QDs film, the carrier recombination region in the PeLEDs is regulated. Finally, deep‐blue PeLEDs with a spectrally stable electroluminescence peak at 458 nm, peak external quantum efficiency of 3.65% and maximum brightness of 223 cd m−2 are realized.

Co‐Interlayer Engineering for Homogenous Phase Quasi‐2‐D Perovskite and High‐Performance Deep‐Blue Light‐Emitting Diodes

AbstractOrganic and inorganic hybrid perovskites are a class of solution‐processable semiconductors that hold significant promise for light‐emitting diode applications. However, the development of efficient blue perovskite light‐emitting diodes (PeLEDs) has remained a critical challenge. Although significant advancements have been achieved in the development of sky‐blue PeLEDs, the performance of pure‐blue and deep‐blue PeLEDs still lags. In this manuscript, by incorporating 1‐cyclohexene‐1‐ethanamine cation (CEA+) into the host 1‐phenylbutylamine cation (PBA+) spacer and fabricating mixed‐cations quasi‐2D perovskites, a homogeneous phase distribution in quasi‐2D perovskite films is achieved through precise tuning of the phase formation energy. The resulting PeLEDs exhibit remarkable performance with an external quantum efficiency (EQE) of 5.8% at 467 nm, which is one of the highest EQEs among the deep‐blue light quasi‐2D PeLED devices with emission wavelengths below 470 nm, Additionally, the device demonstrates a half‐lifetime of ≈ 25 min. Furthermore, the PeLEDs utilizing mixed‐cation perovskite exhibit a stable electroluminescence (EL) spectrum under varying voltage biases, even when the chlorine content in the halogen sites reaches as high as 30%. Overall, this work offers a novel and promising avenue to achieve both high EQE and a stable EL spectrum in blue‐light quasi‐2D PeLEDs.

All-fluorescent white organic light-emitting diodes employing a deep-blue HLCT material simultaneously as emitter and host achieving excellent electroluminescence performance with efficiency roll-off

Simultaneously achieving high efficiency and small efficiency roll-off remains a huge challenge for white organic light-emitting diodes (OLEDs), which greatly restricts their industrial application in the lighting field. Recently developed hybridized local and charge transfer (HLCT) materials have a “hot exciton” channel, which can maximize the utilization rate of excitons and suppress efficiency roll-off via rapid reverse intersystem crossing (RISC) from high-lying triplet state (Tn, n ≥ 2) to singlet state (S1). In this work, employing blue HLCT material pCzAnN as the sensitizing host, by precise concentration management, the traditional fluorescent C545T- and DCJTB-based green and orange-red OLEDs are first fabricated, which achieve the maximum external quantum efficiency (EQE) exceeding the theoretical limit of 5 %, reaching 8.51 % and 6.64 %, respectively. On this basis, by strategic device structure design, all-fluorescent two- and three-color white OLEDs are demonstrated having pCzAnN simultaneously as blue emitter and sensitizing host of C545T and DCJTB. The resulting two- and three-color white devices obtain maximum EQE beyond 5 %. What's more, all three-color white devices exhibit extremely small efficiency roll-off, where the efficiency drops are less than 1 % at a practical luminance of 1000 cd/m2, which is comparable to the best works reported in the literatures. At the same time, the optimized three-color white device realizes ideal white emission, in which the electroluminescence (EL) spectra contain three almost equal intensity emission wavebands accompanied by a high color rendering index of 87. Stable EL spectra under a wide luminance range (3863 ∼ 27710 cd/m2) indicate a huge potential application. We believe this work can provide new idea for developing high-efficiency and low roll-off white OLEDs in the future.

Phase Engineering Reinforced Energy Transfer for High-Performance Blue Perovskite Light-Emitting Diodes.

Layered metal-halide perovskites, a category of self-assembled quantum wells, are of paramount importance in emerging photonic sources, such as lasers and light-emitting diodes (LEDs). Despite high trap density in two-dimensional (2D)perovskites, efficient non-radiative energy funneling from wide- to narrow-bandgap components, sustained by the Förster resonance energy transfer (FRET) mechanism, contributes to efficient luminescence by light or electrical injection. Herein, it is demonstrated that bandgap extension of layered perovskites to the blue-emitting regime will cause sluggish and inefficient FRET, stemming from the tiny spectral overlap between different phases. Motivated by the importance of blue LEDs and inefficient energy transfer in materials with phase polydispersity, wide-bandgap quasi-2D perovskites with narrow phase distribution, improved crystallinity, and the pure crystal orientation perpendicular to the charge transport layer are developed. Based on this emitter, high-performance blue perovskite LEDs with improved electroluminescence (EL) external quantum efficiency (EQE) of 7.9% at 478nm, a narrow full width at half-maximum (FWHM) of 22nm and a more stable EL spectra are achieved. These results provide an important insight into spectrally stable and efficient blue emitters and EL devices based on perovskites.

Efficient, narrow-band, and stable electroluminescence from organoboron-nitrogen-carbonyl emitter

Organic light-emitting diodes (OLEDs) exploiting simple binary emissive layers (EMLs) blending only emitters and hosts have natural advantages in low-cost commercialization. However, previously reported OLEDs based on binary EMLs hardly simultaneously achieved desired comprehensive performances, e.g., high efficiency, low efficiency roll-off, narrow emission bands, and high operation stability. Here, we report a molecular-design strategy. Such a strategy leads to a fast reverse intersystem crossing rate in our designed emitter h-BNCO-1 of 1.79×105 s−1. An OLED exploiting a binary EML with h-BNCO-1 achieves ultrapure emission, a maximum external quantum efficiency of over 40% and a mild roll-off of 14% at 1000 cd·m−2. Moreover, h-BNCO-1 also exhibits promising operational stability in an alternative OLED exploiting a compact binary EML (the lifetime reaching 95% of the initial luminance at 1000 cd m−2 is ~ 137 h). Here, our work has thus provided a molecular-design strategy for OLEDs with promising comprehensive performance.