Low External Quantum Efficiency Research Articles

Numerical simulation of deep ultraviolet LED, micro-LED, and nano-LED with different emission wavelengths based on FDTD

The current low external quantum efficiency (EQE) of deep ultraviolet (DUV) LEDs and micro-LEDs is largely attributed to their low light extraction efficiency (LEE). To address this issue and increase the LEE of DUV devices, various strategies such as reducing size, modifying surface with nanostructures and roughening substrates have been proposed. While some studies have investigated the effects of nanopillar and size on DUV LED, there remains a lack of systematic research on the LEE enhancement mechanism across different wavelengths and sizes of DUV LEDs, micro-LEDs, and nano-LEDs. Therefore, in this study, we employed the numerical simulation method to explore the LEE, near-field intensity distribution, and far-field light intensity distribution from various angles for DUV LEDs, micro-LEDs, and nano-LEDs with wavelengths of 255 nm, 260 nm, and 275 nm, respectively. Our findings reveal a significant improvement in the LEE of DUV nano-LEDs and micro-LEDs, accompanied by reduced divergence angles. Moreover, we observe that longer wavelengths correspond to higher LEE values for devices with similar size. This enhancement in LEE is attributed to factors such as increased sidewall emission and reduced p-GaN absorption. Our investigation indicates that as the size of the DUV device decreases, the sidewall LEE for both transverse electric (TE) and transverse magnetic (TM) modes increases, with TM mode exhibiting a larger enhancement. This enhancement is mainly attributed to the reduction of total reflection within the DUV LEDs and micro-LEDs resulting from size reduction. Despite this, TE mode remains the main contributor to overall LEE. Additionally, our study reveals a reduction in p-GaN absorption of DUV light with decreasing device size, further contributing to the enhancement of LEE in DUV micro-LEDs and nano-LEDs. The increased LEE and reduced divergence angles of small-size DUV micro-LEDs and nano-LEDs not only promote lower power consumption but also enable easier optical system coupling. Consequently, these advancements have significant potential in optical wireless communication, charge management and high-precision lithography.

Advancements in Micro-LED Performance through Nanomaterials and Nanostructures: A Review.

Micro-light-emitting diodes (μLEDs), with their advantages of high response speed, long lifespan, high brightness, and reliability, are widely regarded as the core of next-generation display technology. However, due to issues such as high manufacturing costs and low external quantum efficiency (EQE), μLEDs have not yet been truly commercialized. Additionally, the color conversion efficiency (CCE) of quantum dot (QD)-μLEDs is also a major obstacle to its practical application in the display industry. In this review, we systematically summarize the recent applications of nanomaterials and nanostructures in μLEDs and discuss the practical effects of these methods on enhancing the luminous efficiency of μLEDs and the color conversion efficiency of QD-μLEDs. Finally, the challenges and future prospects for the commercialization of μLEDs are proposed.

Advancements in Interfacial Engineering for Perovskite Light-Emitting Diodes.

Perovskite light-emitting diodes (PeLEDs) have gained significant attention due to their promising optoelectronic properties and potential applications in the fields of lighting and display devices. Despite their potential, PeLEDs face challenges related to stability, high turn-on voltage, and low external quantum efficiency (EQE) which has restricted their broad acceptance. Most research efforts have predominantly focused on refining the properties of the perovskite films. However, it is becoming more apparent that interfacial layers and device architecture are crucial for achieving stability and high efficiency, making them indispensable components in PeLED development. This perspective highlights remarkable advancements in PeLED devices, with a primary focus on modifying adjacent layers interfacing with the perovskite film.

Roadmap on Perovskite light-emitting diodes

Abstract In recent years, the field of metal-halide perovskite emitters has rapidly emerged as a new community in solid-state lighting. Their exceptional optoelectronic properties have contributed to the rapid rise in external quantum efficiencies (EQEs) in perovskite light-emitting diodes (PeLEDs) from <1% (in 2014) to approaching 30% (in 2023) across a wide range of wavelengths. However, several challenges still hinder their commercialization, including the relatively low EQEs of blue/white devices, limited EQEs in large-area devices, poor device stability, as well as the toxicity of the easily accessible lead components and the solvents used in the synthesis and processing of PeLEDs. This roadmap addresses the current and future challenges in PeLEDs across fundamental and applied research areas, by sharing the community's perspectives. This work will provide the field with practical guidelines to advance PeLED development and facilitate more rapid commercialization.

Investigation of optical polarization characteristics of ultraviolet-C AlGaN multiple quantum wells by angle-resolved cathodoluminescence

AlGaN-based ultraviolet-C (UV-C) light-emitting diodes (LEDs) face challenges related to their extremely low external quantum efficiency, which is predominantly attributed to the remarkably inadequate transverse magnetic (TM) light extraction efficiency (LEE). In this study, we employ angle-resolved cathodoluminescence (ARCL) spectroscopy to assess the optical polarization of (0001)-oriented AlGaN multiple quantum well (MQW) structures in UV-C LEDs, in conjunction with a focused ion beam and scanning electron microscopy (FIB/SEM) system to etch samples with various inclination angles (θ) of sidewall. This technique effectively distinguishes the spatial distribution of TM- and transverse electric (TE)-polarized photons contributing to the luminescence of the MQW structure. CL spectroscopy confirms that UV-C LEDs with a θ of 35° exhibit the highest CL signal compared to samples with other θ. Furthermore, we establish a model using finite difference time domain (FDTD) simulation to validate the mechanism of the outcomes. The complementary contribution of TM and TE photons at different specific angles are distinguished by ARCL and confirmed by simulation. At angles near the sidewall, the CL is dominated by the TM photons, which mainly contribute to the increased LEE and the decreased degree of polarization (DOP) to make the spatial distribution of CL more uniform. Additionally, this method allows us to analyze the polarization of light without the need for polarizers, enabling the differentiation of TE and TM modes. This distinction provides flexibility for selecting different emission mode based on various application requirements. The presented approach not only opens up new opportunities for enhanced UV-C light extraction but also provides valuable insights for future endeavors in device fabrication and epitaxial film growth.

Strongly-Confined CsPbBr3 Perovskite Quantum Dots with Ultralow Trap Density and Narrow Size Distribution for Efficient Pure-Blue Light-Emitting Diodes.

The development of pure-blue perovskite light-emitting diodes (PeLEDs) faces challenges of spectral stability and low external quantum efficiency (EQE) due to phase separation in mixed halide compositions. Perovskite quantum dots (QDs) with strong confinement effects are promising alternatives to achieve high-quality pure-blue PeLEDs, yet their performance is often hindered by the poor size distribution and high trap density. A strategy combining thermodynamic control with a polishing-driven ligand exchange process to produce high-quality QDs is developed. The strongly-confined pure-blue (≈470nm) CsPbBr3 QDs exhibit narrow size distribution (12% dispersion) and are achieved in Br-rich ion environment based on growth thermodynamic control. Subsequent polishing-driven ligand exchange process removes imperfect surface sites and replaces initial long-chain organic ligands with short-chain benzene ligands. The resulting QDs exhibit high photoluminescence quantum yield (PLQY) to near-unity. The resulting PeLEDs exhibit a pure-blue electroluminescence (EL) emission at 472nm with narrow full-width at half-maximum (FWHM) of 25nm, achieving a maximum EQE of 10.7% and a bright maximum luminance of 7697cdm-2. The pure-blue PeLEDs show ultrahigh spectral stability under high voltage, a low roll-off of EQE, and an operational half-lifetime (T50) of 127min at an initial luminance of 103cdm-2 under continuous operation.

Reduced phonon coupling via controlled defect levels in blue emitting CsPbBr3 nanoplatelets

Metal-halide perovskites (MHPs) are promising materials for light-emitting diodes (LEDs) because of their high color purity, wide gamut, and low-cost processing. However, blue-emitting MHP LEDs exhibit low external quantum efficiencies because they are more susceptible to defect states with a larger energy bandgap compared to their green and red counterparts. Current strategies for achieving blue-emitting MHP LEDs involve compositional engineering; however, the ion migration of mixed halides imposes significant challenges related to abundant trap states. Therefore, in this study, we systematically investigated the effects of short organic and inorganic ligands with characteristic molecular structures and adjacent moieties on the optoelectronic characteristics of low-dimensional CsPbBr3 nanoplatelets (NPLs) used as blue emitters in PeLEDs. Inorganic ligand (i.e., hydrazine monohydrobromide; HZBr) treatment achieved the most significant photoluminescence enhancement (∼10 fold) while preserving crystalline morphology and colloidal stability. Temperature-dependent photophysical properties reveal that HZBr treatment eliminates band tail states arising from lower defect levels in highly confined CsPbBr3 NPLs. Therefore, it suppresses defect trapping and electron–phonon coupling, thereby reducing thermal quenching properties. The HZBr-treated NPLs were integrated into blue perovskite LEDs and demonstrated a narrow emission peak at 471 nm.

ZnS-coated Yb3+-doped perovskite quantum dots: A stable and efficient quantum cutting photon energy converter for silicon-based electronics

Yb3+ doped lead halide perovskite quantum dots (PeQDs) with efficient quantum cutting emission are thought to be the most promising photon energy converter for improving the performance of silicon-based electronics. Nevertheless, the low external quantum efficiency (EQE) and instability make it unfeasible for industrial use. Here, we present a unique PeQDs@ ZnS core–shell device that achieves outstanding stability and up to 39 % EQE by effectively controlling energy transfer from the PeQDs to the Yb3+ through ZnS coating. These advances are attributed to the large UV absorption and the strong localized effect of the ZnS shells on the conduction band electrons of the PeQDs. Density functional theory (DFT) first-principles simulations indicate that ZnS coating can facilitate the energy transfer of PeQDs to Yb3+. Power conversion efficiency (PCE) of silicon solar cells was significantly enhanced by ZnS-coated Yb3+ doped PeQDs, yielding a noteworthy 13.5 % relative PCE improvement over 30 measurement sets. Significantly, the stability of SSCs with ZnS-coated PeQDs films is considerably improved, resulting in a capped device T80 lifespan of up to 11,224 h. Moreover, ZnS-coated PeQDs films can significantly boost the EQE of silicon photodiodes (Si-PDs) and extend their response to deep ultraviolet light. This paper presents an efficient and consistently stable photon energy converter with great commercialization potential.

B,N‐Embedded Hetero[9]helicene Toward Highly Efficient Circularly Polarized Electroluminescence

AbstractThe intrinsic helical π‐conjugated skeleton makes helicenes highly promising for circularly polarized electroluminescence (CPEL). Generally, carbon helicenes undergo low external quantum efficiency (EQE), while the incorporation of a multi‐resonance thermally activated delayed fluorescence (MR‐TADF) BN structure has led to an improvement. However, the reported B,N‐embedded helicenes all show low electroluminescence dissymmetry factors (gEL), typically around 1×10−3. Therefore, the development of B,N‐embedded helicenes with both a high EQE and gEL value is crucial for achieving highly efficient CPEL. Herein, a facile approach to synthesize B,N‐embedded hetero[9]helicenes, BN[9]H, is presented. BN[9]H shows a bright photoluminescence with a maximum at 578 nm with a high luminescence dissymmetry factor (|glum|) up to 5.8×10−3, attributed to its inherited MR‐TADF property and intrinsic helical skeleton. Furthermore, circularly polarized OLED devices incorporating BN[9]H as an emitter show a maximum EQE of 35.5 %, a small full width at half‐maximum of 48 nm, and, more importantly, a high |gEL| value of 6.2×10−3. The Q‐factor (|EQE×gEL|) of CP‐OLEDs is determined to be 2.2×10−3, which is the highest among helicene analogues. This work provides a new approach for the synthesis of higher helicenes and paves a new way for the construction of highly efficient CPEL materials.

B,N-Embedded Hetero[9]helicene Toward Highly Efficient Circularly Polarized Electroluminescence.

The intrinsic helical π-conjugated skeleton makes helicenes highly promising for circularly polarized electroluminescence (CPEL). Generally, carbon helicenes undergo low external quantum efficiency (EQE), while the incorporation of a multi-resonance thermally activated delayed fluorescence (MR-TADF) BN structure has led to an improvement. However, the reported B,N-embedded helicenes all show low electroluminescence dissymmetry factors (gEL), typically around 1×10-3. Therefore, the development of B,N-embedded helicenes with both a high EQE and gEL value is crucial for achieving highly efficient CPEL. Herein, a facile approach to synthesize B,N-embedded hetero[9]helicenes, BN[9]H, is presented. BN[9]H shows a bright photoluminescence with a maximum at 578 nm with a high luminescence dissymmetry factor (|glum|) up to 5.8×10-3, attributed to its inherited MR-TADF property and intrinsic helical skeleton. Furthermore, circularly polarized OLED devices incorporating BN[9]H as an emitter show a maximum EQE of 35.5 %, a small full width at half-maximum of 48 nm, and, more importantly, a high |gEL| value of 6.2×10-3. The Q-factor (|EQE×gEL|) of CP-OLEDs is determined to be 2.2×10-3, which is the highest among helicene analogues. This work provides a new approach for the synthesis of higher helicenes and paves a new way for the construction of highly efficient CPEL materials.

Improvement of light extraction efficiency in AlGaInP-based vertical miniaturized-light-emitting diodes via surface texturing.

AlGaInP-based light-emitting diodes (LEDs) suffer from a low external quantum efficiency (EQE), which is mainly restrained by the poor light extraction efficiency. Here, we demonstrate AlGaInP-based vertical miniaturized-LEDs (mini-LEDs) with a porous n-AlGaInP surface using a wet etching process to boost light extraction. We investigated the effects of etching time on the surface morphology of the porous n-AlGaInP surface. We found that as the etching time is prolonged, the density of pores increases initially and decreases subsequently. In comparison with the vertical mini-LED with a smooth n-AlGaInP surface, the vertical mini-LEDs with the porous n-AlGaInP surface reveal improvement in light output power and EQE, meanwhile, without the deterioration of electrical performance. The highest improvement of 38.9% in EQE measured at 20 mA is observed from the vertical mini-LED with the maximum density of the pores. Utilizing a three-dimensional finite-difference time-domain method, we reveal the underlying mechanisms of improved performance, which are associated with suppressed total internal reflection and efficient light scattering effect of the pores.

Improved light extraction efficiency of AlGaN DUV light emitting diodes using Al/MgF2-based highly reflective film

AlGaN DUV light emitting diodes (DUV-LEDs) (275 nm emission) are safe, eco-friendly and smart alternatives for inactivating viruses and bacteria. However, DUV-LEDs suffer from the main bottleneck of low external quantum efficiencies, which are strongly associated with the low light extraction efficiency caused by the strong optical polarisation of Al-rich AlGaN. Optical simulation results show that the luminous intensity of DUV-LEDs was increased by 10% owing to the synergistic effect of the sidewalls and substrates. The optical power of DUV-LEDs was increased to 16.8%, the far-field pattern was expanded to 130 degrees and the emission intensity was more focused on the central region, proving that the highly reflective sidewalls and substrates could re-direct the sideways-travelling photons for extraction. Moreover, we also investigated the reflective mechanism of Al/MgF2 layers. Optimizing the refractive index distribution of Al/MgF2 layers could change the electric field intensity and improve the reflectivity. At the same time, the temperature of the sample after coating was significantly reduced by 6.83%. Thermal radiation benefits and the high stability of bonding interfaces are the main reasons to reduce the temperature of DUV-LEDs after Al/MgF2 coating. The present strategy is proposed from the point of view of chip fabrication, which is cost-effective and able to be manufactured at a large scale.

Electrically Confined Electroluminescence of Neutral Excitons in WSe2 Light-Emitting Transistors.

Monolayer transition metal dichalcogenides (TMDs) have drawn significant attention for their potential in optoelectronic applications due to their direct band gap and exceptional quantum yield. However, TMD-based light-emitting devices have shown low external quantum efficiencies as imbalanced free carrier injection often leads to the formation of non-radiative charged excitons, limiting practical applications. Here, electrically confined electroluminescence (EL) of neutral excitons in tungsten diselenide (WSe2) light-emitting transistors (LETs) based on the van der Waals heterostructure is demonstrated. The WSe2 channel is locally doped to simultaneously inject electrons and holes to the 1D region by a local graphene gate. At balanced concentrations of injected electrons and holes, the WSe2 LETs exhibit strong EL with a high external quantum efficiency (EQE) of ≈8.2 % at room temperature. These experimental and theoretical results consistently show that the enhanced EQE could be attributed to dominant exciton emission confined at the 1D region while expelling charged excitons from the active area by precise control of external electric fields. This work shows a promising approach to enhancing the EQE of 2D light-emitting transistors and modulating the recombination of exciton complexes for excitonic devices.

Reduction of Non‐Radiative Losses in Trap‐Free Organic Light‐Emitting Diodes by Dilution with A Large Bandgap Host

AbstractThe emitter 9,9′,9′'‐(5‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl)benzene‐1,2,3‐triyl)tris(9H‐carbazole) (3CzTRZ) seems an ideal candidate for efficient single‐layer blue organic light‐emitting diodes (OLEDs). It combines trap‐free electron and hole transport with thermally activated delayed fluorescence (TADF) for triplet harvesting. However, in spite of the absence of charge trapping defects, neat films of 3CzTRZ suffer from a low photoluminescence quantum yield (PLQY) of only 40%. Time‐resolved photoluminescence measurements reveal that the low PLQY results from the fact that next to fast intersystem crossing the rate for reverse intersystem crossing is very slow and nearly similar to the rate of non‐radiative recombination of triplet excitons to the ground state. This loss process of non‐radiative triplet decay is even more pronounced in OLEDs due to the 75% direct triplet‐exciton formation, resulting in a low external quantum efficiency (EQE) of 4.5%. By diluting 3CzTRZ in a large bandgap host, the triplet lifetime is increased by at least an order of magnitude, resulting in an enhanced PLQY of 70% and a more than three‐fold enhancement of the EQE to 15% in a single‐layer blue OLED. Device simulations confirm that the increased EQE can be ascribed to an elongated triplet lifetime upon dilution of the emitter in a host matrix.

Midwave resonant cavity infrared detectors (RCIDs) with suppressed background noise.

We report a resonant cavity infrared detector (RCID) with an InAsSb/InAs superlattice absorber with a thickness of only ≈ 100 nm, a 33-period GaAs/Al0.92Ga0.08As distributed Bragg reflector bottom mirror, and a Ge/SiO2/Ge top mirror. At a low bias voltage of 150 mV, the external quantum efficiency (EQE) reaches 58% at the resonance wavelength λres ≈ 4.6 µm, with linewidth δλ = 19-27 nm. The thermal background current for a realistic system scenario with f/4 optic that views a 300 K scene is estimated by integrating the photocurrent generated by background spanning the entire mid-IR spectral band (3-5 µm). The resulting specific detectivity is a factor of 3 lower than for a state-of-the-art broadband HgCdTe device at 300 K, where dark current dominates the noise. However, at 125 K where the suppression of background noise becomes critical, the estimated specific detectivity D* of 5.5 × 1012 cm Hz½/W is more than 3× higher. This occurs despite a non-optimal absorber cut-off that causes the EQE to decrease rapidly with decreasing temperature, e.g., to 33% at 125 K. The present RCID's advantage over the broadband device depends critically on its low EQE at non-resonance wavelengths: ≤ 1% in the range 3.9-5.5 µm. Simulations using NRL MULTIBANDS indicate that impact ionization in the bottom contact and absorber layers dominates the dark current at near ambient temperatures. We expect future design modifications to substantially enhance D* throughout the investigated temperature range of 100-300 K.

Synergistic Enhancement of Near-Infrared Emission in CsPbCl3 Host via Co-Doping with Yb3+ and Nd3+ for Perovskite Light Emitting Diodes.

Perovskite nanocrystals (PeNCs) have emerged as a promising class of luminescent materials offering size and composition-tunable luminescence with high efficiency and color purity in the visible range. PeNCs doped with Yb3+ ions, known for their near-infrared (NIR) emission properties, have gained significant attention due to their potential applications. However, these materials still face challenges with weak NIR electroluminescence (EL) emission and low external quantum efficiency (EQE), primarily due to undesired resonance energy transfer (RET) occurring between the host and Yb3+ ions, which adversely affects their emission efficiency and device performance. Herein, we report the synergistic enhancement of NIR emission in a CsPbCl3 host through co-doping with Yb3+/Nd3+ ions for perovskite LEDs (PeLEDs). The co-doping of Yb3+/Nd3+ ions in a CsPbCl3 host resulted in enhanced NIR emission above 1000 nm, which is highly desirable for NIR optoelectronic applications. This cooperative energy transfer between Yb3+ and Nd3+ can enhance the overall efficiency of energy conversion. Furthermore, the PeLEDs incorporating the co-doped CsPbCl3/Yb3+/Nd3+ PeNCs as an emitting layer exhibited significantly enhanced NIR EL compared to the single doped PeLEDs. The optimized co-doped PeLEDs showed improved device performance, including increased EQE of 6.2% at 1035 nm wavelength and low turn-on voltage. Our findings highlight the potential of co-doping with Yb3+ and Nd3+ ions as a strategy for achieving synergistic enhancement of NIR emission in CsPbCl3 perovskite materials, which could pave the way for the development of highly efficient perovskite LEDs for NIR optoelectronic applications.

CsPbBr3@Glass Nanocomposite with Green‐Emitting External Quantum Efficiency of 75% for Backlit Display

AbstractRobust amorphous glass protected CsPbBr3 (CsPbBr3@glass) perovskite quantum dots (PeQDs) with ultra‐pure green emission and superior long‐term stability are highly desirable for developing wide‐color‐gamut liquid crystal displays. However, most of the reported CsPbBr3@glass nanocomposites are subject to low external quantum efficiency (EQE). This work demonstrates that ZrO2 additive has an “accumulation” effect on the borosilicate glass network structure to promote in situ nucleation/growth of PeQDs inside glass rather than self‐crystallization. This effect is beneficial in reducing surface defects, improving the quality of PeQDs, and thus boosting radiative recombination of excitons. As a consequence, the as‐prepared CsPbBr3@glass shows a record EQE of up to 75% and can pass the accelerated aging tests at 85 °C/85% RH for 1000 h and blue light irradiation over 2000 h. Finally, a prototype display using CsPbBr3@glass‐based straight‐down backlit unit is designed and gains more favorable responses in blind selection tests for its high brightness of 2647 cd m−2 and high color purity of 88%. The findings will pave the way for realizing the commercial application of CsPbBr3@glass nanocomposite in PeQDs‐converted backlit display.

Plasmon resonance-enhanced graphene nanofilm-based dual-band infrared silicon photodetector

Graphene-based photodetectors have attracted much attention due to their unique properties, such as high-speed and wide-band detection capability. However, they suffer from very low external quantum efficiency in the infrared (IR) region and lack spectral selectivity. Here, we construct a plasmon-enhanced macro-assembled graphene nanofilm (nMAG) based dual-band infrared silicon photodetector. The Au plasmonic nanostructures improve the absorption of long-wavelength photons with energy levels below the Schottky barrier (between metal and Si) and enhance the interface transport of electrons. Combined with the strong photo-thermionic emission (PTI) effect of nMAG, the nMAG–Au–Si heterojunctions show strong dual-band detection capability with responsivities of 52.9 mA/W at 1342 nm and 10.72 mA/W at 1850 nm, outperforming IR detectors without plasmonic nanostructures by 58–4562 times. The synergy between plasmon–exciton resonance enhancement and the PTI effect opens a new avenue for invisible light detection.

Understanding and Hindering the Electron Leakage in Green InP Quantum‐Dot Light‐Emitting Diodes

Indium phosphide (InP) quantum‐dot light‐emitting diodes (QLEDs) are considered as one of the most promising candidates for emerging displays owing to their good luminous performance and environmentally friendly properties. The operation of green InP QLEDs relies on the radiative recombination of electrically generated excitons, as in most QLEDs; however, the electrons injected into green InP QLEDs can easily pass through the quantum‐dot (QD) layer, resulting in a carrier imbalance and low external quantum efficiency (EQE). Herein, the mechanism of electron leakage in green InP QLEDs is revealed. Based on comparative experiments and simulations of the carrier concentration distribution, the path of electron leakage is determined and it is found that the root cause is the large Fermi energy difference between green InP QDs and indium tin oxide (ITO). To solve this problem, an ultrathin LiF layer is applied to modify the work function of the ITO, which simultaneously hinders electron leakage and enhances hole injection. Benefiting from a more balanced carrier injection, the maximum EQE of green InP QLEDs improves from 4.70% to 9.14%. In these findings, a universal mechanism is provided for hindering electron leakage in green InP QLEDs, indicating the feasibility of developing highly efficient green InP QLEDs.

1,2,4-Triazole-Ligand-based Iridium(III) complex and its use in blue phosphorescent organic light-emitting diodes

Organic light-emitting diodes (OLEDs) play a key role in modern flexible displays. Although stable and efficient red- and green-emitting phosphors have been developed, the applications of blue emitters are limited due to their poor chemical and electrochemical stability, and thus, they require further development. Herein, we report the preparation and full characterization of IrTrz, a 3-methyl-5-phenyl-1H-1,2,4-triazole-ligand-based facial-homoleptic iridium complex. Single-crystal X-ray diffractometry results suggested that the complex is a facial isomer with C3 point symmetry. The complex exhibited a blue emission band centered at ∼450 nm in both solution and the film state at ambient temperature; moreover, it showed a very narrow full-width at half maximum value (55 nm) and a moderate photoluminescence quantum yield (33%). The complex showed high thermal stability, with 5%-weight-loss and glass-transition temperatures of 324 and 210 °C, respectively. Consecutive cyclic voltammetry measurements revealed outstanding electrochemical stability of the complex. Therefore, multilayer phosphorescent OLEDs that use IrTrz as the blue emitter were fabricated with two types of host material: (3,3′-di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) and 9-(dibenzo[b,d]thiophen-4-yl)-9H-3,9′-bicarbazole (4DBTCz)). In particular, the 4DBTCz-based devices exhibited low turn-on voltages (∼5.0 V) and high external quantum efficiencies (>11%) with a Commission Internationale de l’Eclairage y-coordinate of 0.2. Moreover, the devices demonstrated stable operational lifetimes that exceeded 690 h (for mCBP) and 390 h (for 4DBTCz) at 100 cd/m2. Therefore, we believe that the 1,2,4-triazole-ligand-based Ir(III) complex is a promising blue-phosphorescent emitter material for applications in stable and efficient OLED devices.