Showing papers on "Diode published in 2022"
TL;DR: In this paper , a review of the development of perovskite light-emitting diodes is presented, exploring the key challenges involved in creating efficient and stable devices.
Abstract: Light-emitting diodes based on halide perovskites have undergone rapid development in recent years and can now offer external quantum efficiencies of over 23%. However, the practical application of such devices is still limited by a number of factors, including the poor efficiency of blue-emitting devices, difficulty in accessing emission wavelengths above 800 nm, a decrease in external quantum efficiency at high current density, a lack of understanding of the effect of the electric field on mobile ions present in the perovskite materials, and short device lifetimes. Here we review the development of perovskite light-emitting diodes. We examine the key challenges involved in creating efficient and stable devices, and consider methods to alleviate the poor efficiency of blue-emitting devices, leverage emission in the long infrared region and create spin-polarized light-emitting diodes. This Review examines the development of perovskite light-emitting diodes, exploring the key challenges involved in creating efficient and stable devices.
131 citations
TL;DR: In this paper , a Ga2O3 heterojunction PN diodes with holes injection was proposed to induce conductivity modulation and low resistance in a low-doping Ga 2O3 material.
Abstract: Ultra-wide bandgap semiconductor Ga2O3 based electronic devices are expected to perform beyond wide bandgap counterparts GaN and SiC. However, the reported power figure-of-merit hardly can exceed, which is far below the projected Ga2O3 material limit. Major obstacles are high breakdown voltage requires low doping material and PN junction termination, contradicting with low specific on-resistance and simultaneous achieving of n- and p-type doping, respectively. In this work, we demonstrate that Ga2O3 heterojunction PN diodes can overcome above challenges. By implementing the holes injection in the Ga2O3, bipolar transport can induce conductivity modulation and low resistance in a low doping Ga2O3 material. Therefore, breakdown voltage of 8.32 kV, specific on-resistance of 5.24 mΩ⋅cm2, power figure-of-merit of 13.2 GW/cm2, and turn-on voltage of 1.8 V are achieved. The power figure-of-merit value surpasses the 1-D unipolar limit of GaN and SiC. Those Ga2O3 power diodes demonstrate their great potential for next-generation power electronics applications.
102 citations
TL;DR: In this paper , the authors developed a method for the production of ultra-bright, efficient and stable perovskite light-emitting diodes, achieved with a simple in situ reaction process.
Abstract: Metal halide perovskites are attracting a lot of attention as next-generation light-emitting materials owing to their excellent emission properties, with narrow band emission1–4. However, perovskite light-emitting diodes (PeLEDs), irrespective of their material type (polycrystals or nanocrystals), have not realized high luminance, high efficiency and long lifetime simultaneously, as they are influenced by intrinsic limitations related to the trade-off of properties between charge transport and confinement in each type of perovskite material5–8. Here, we report an ultra-bright, efficient and stable PeLED made of core/shell perovskite nanocrystals with a size of approximately 10 nm, obtained using a simple in situ reaction of benzylphosphonic acid (BPA) additive with three-dimensional (3D) polycrystalline perovskite films, without separate synthesis processes. During the reaction, large 3D crystals are split into nanocrystals and the BPA surrounds the nanocrystals, achieving strong carrier confinement. The BPA shell passivates the undercoordinated lead atoms by forming covalent bonds, and thereby greatly reduces the trap density while maintaining good charge-transport properties for the 3D perovskites. We demonstrate simultaneously efficient, bright and stable PeLEDs that have a maximum brightness of approximately 470,000 cd m−2, maximum external quantum efficiency of 28.9% (average = 25.2 ± 1.6% over 40 devices), maximum current efficiency of 151 cd A−1 and half-lifetime of 520 h at 1,000 cd m−2 (estimated half-lifetime >30,000 h at 100 cd m−2). Our work sheds light on the possibility that PeLEDs can be commercialized in the future display industry. The authors develop a method for the production of ultra-bright, efficient and stable perovskite light-emitting diodes, achieved with a simple in situ reaction process.
91 citations
91 citations
TL;DR: In this article , a two-step hydrothermal process was used to construct a Schottky/step-scheme heterojunction for boosting photocatalytic hydrogen generation activity.
80 citations
TL;DR: In this paper , the work functions of laser-induced graphene (LIG) were controlled by adjusting the frequency or speed of the laser, and a series of LIG/GaOx Schottky photodetectors were formed.
Abstract: Laser-induced graphene (LIG) is a simple, environmentally friendly, efficient, and less costly method, as well as can form various shapes on a flexible substrate in situ without the use of masks. More importantly, it can tune the work function of LIG easily by changing laser parameters to control the transportation of carriers. In this work, the work functions of LIG were controlled by adjusting the frequency or speed of the laser, and a series of LIG/GaOx Schottky photodetectors were formed. When the work function of the graphene increases, the Fermi energy is shifted below the crossing point of the Π and Π* bands, and then more electrons or holes can be activated to participate in the conduction process, resulting in low resistance. Meanwhile, a large built-in electric field can be formed when using a high work function LIG, which is more beneficial to separate photo-generated carriers. Enabled by the controllable LIG, LIG/GaOx Schottky photodetectors can be modulated to have high photoresponsivity or self-powered characteristics. Our work provides a high-performance photodetector with excellent mechanical flexibility and long-life stability, promising applications in the flexible optoelectronic fields.
69 citations
65 citations
TL;DR: In this article , a hole-transport polymers with simultaneous low electron affinity and reduced energetic disorder is used to eliminate electron leakage at the organic/inorganic interface for green and blue quantum-dot light-emitting diodes.
Abstract: Quantum-dot light-emitting diodes (QD-LEDs) promise a new generation of efficient, low-cost, large-area and flexible electroluminescent devices. However, the inferior performance of green and blue QD-LEDs compared with their red counterpart is hindering the commercialization of QD-LEDs in display and solid-state lighting applications. Here we demonstrate green and blue QD-LEDs with ~100% conversion of the injected charge carriers into emissive excitons. The key to success is the elimination of electron leakage at the organic/inorganic interface by using hole-transport polymers with simultaneous low electron affinity and reduced energetic disorder. Our devices exhibit high external quantum efficiencies over a wide range of luminance values (peak external quantum efficiencies of 28.7% for green and 21.9% for blue) and excellent stability (extrapolated T95 lifetime is 580,000 h for green and 4,400 h for blue QD-LEDs). We expect our work to provide a general strategy for eliminating charge leakage in solution-processed LEDs featuring organic/inorganic interfaces. A new strategy to reduce charge leakage in quantum-dot light-emitting diodes enables high external quantum efficiencies of 28.7% and 21.9% and excellent T95 lifetimes of 580,000 h and 4,400 h for green and blue devices, respectively.
65 citations
TL;DR: In this article , a highly sensitive methane (CH4) sensor based on light-induced thermoelastic spectroscopy (LITES) using a 2.33 µm diode laser with high power is demonstrated for the first time.
Abstract: In this manuscript, a highly sensitive methane (CH4) sensor based on light-induced thermoelastic spectroscopy (LITES) using a 2.33 µm diode laser with high power is demonstrated for the first time. A quartz tuning fork (QTF) with an intrinsic resonance frequency of 32.768 kHz was used to detect the light-induced thermoelastic signal. A Herriot multi-pass cell with an effective optical path of 10 m was adopted to increase the laser absorption. The laser wavelength modulation depth and concentration response of this CH4-LITES sensor were investigated. The sensor showed excellent long term stability when Allan deviation analysis was performed. An adaptive Savitzky-Golay (S-G) filtering algorithm with χ2 statistical criterion was firstly introduced to the LITES technique. The SNR of this CH4-LITES sensor was improved by a factor of 2.35 and the minimum detection limit (MDL) with an integration time of 0.1 s was optimized to 0.5 ppm. This reported CH4-LITES sensor with sub ppm-level detection ability is of great value in applications such as environmental monitoring and industrial safety.
62 citations
TL;DR: In this paper , the state-of-the-art in colloidal metal-halide perovskite nanocrystals (MHP NCs) is discussed, and the challenges associated with their thickness-controlled synthesis, environmental and thermal stability, and their application in making efficient LEDs are discussed.
Abstract: Colloidal metal-halide perovskite nanocrystals (MHP NCs) are gaining significant attention for a wide range of optoelectronics applications owing to their exciting properties, such as defect tolerance, near-unity photoluminescence quantum yield, and tunable emission across the entire visible wavelength range. Although the optical properties of MHP NCs are easily tunable through their halide composition, they suffer from light-induced halide phase segregation that limits their use in devices. However, MHPs can be synthesized in the form of colloidal nanoplatelets (NPls) with monolayer (ML)-level thickness control, exhibiting strong quantum confinement effects, and thus enabling tunable emission across the entire visible wavelength range by controlling the thickness of bromide or iodide-based lead-halide perovskite NPls. In addition, the NPls exhibit narrow emission peaks, have high exciton binding energies, and a higher fraction of radiative recombination compared to their bulk counterparts, making them ideal candidates for applications in light-emitting diodes (LEDs). This review discusses the state-of-the-art in colloidal MHP NPls: synthetic routes, thickness-controlled synthesis of both organic-inorganic hybrid and all-inorganic MHP NPls, their linear and nonlinear optical properties (including charge-carrier dynamics), and their performance in LEDs. Furthermore, the challenges associated with their thickness-controlled synthesis, environmental and thermal stability, and their application in making efficient LEDs are discussed.
62 citations
TL;DR: In this paper , a tailor-made ternary halogen-free solvent (naphthene, n−tridecane, and n−nonane) recipe was proposed for CsPbX3 perovskite QDs and their corresponding inkjet-printed QLEDs.
Abstract: Toward next‐generation electroluminescent quantum dot (QD) displays, inkjet printing technique has been convinced as one of the most promising low‐cost and large‐scale manufacturing of patterned quantum dot light‐emitting diodes (QLEDs). The development of high‐quality and stable QD inks is a key step to push this technology toward practical applications. Herein, a universal ternary‐solvent‐ink strategy is proposed for the cesium lead halides (CsPbX3) perovskite QDs and their corresponding inkjet‐printed QLEDs. With this tailor‐made ternary halogen‐free solvent (naphthene, n‐tridecane, and n‐nonane) recipe, a highly dispersive and stable CsPbX3 QD ink is obtained, which exhibits much better printability and film‐forming ability than that of the binary solvent (naphthene and n‐tridecane) system, leading to a much better qualitied perovskite QD thin film. Consequently, a record peak external quantum efficiency (EQE) of 8.54% and maximum luminance of 43 883.39 cd m−2 is achieved in inkjet‐printed green perovskite QLEDs, which is much higher than that of the binary‐solvent‐system‐based devices (EQE = 2.26%). Moreover, the ternary‐solvent‐system exhibits a universal applicability in the inkjet‐printed red and blue perovskite QLEDs as well as cadmium (Cd)‐based QLEDs. This work demonstrates a new strategy for tailor‐making a general ternary‐solvent‐QD‐ink system for efficient inkjet‐printed QLEDs as well as the other solution‐processed electronic devices in the future.
TL;DR: In this article , the authors used 2,3-diaminopyridine as a single precursor to synthesize colorful CDs in different pH conditions, by simply regulating the reaction media from alkali to neutral to acid, bright CDs emitting violet, green, and orange fluorescence, respectively.
TL;DR: In this paper, the authors implemented beveled-mesa NiO/Ga2O3 p-n heterojunction diodes (HJDs) into a 500-W power factor correction (PFC) system circuit, achieving high conversion efficiency of 98.5% with 100-min stable operating capability.
Abstract: The technical progress of Ga2O3 power diodes is now stuck at a critical point where a lack of performance evaluation and reliability validation at the system-level applications seriously limits their further development and even future commercialization. In this letter, by implementing beveled-mesa NiO/Ga2O3 p–n heterojunction diodes (HJDs) into a 500-W power factor correction (PFC) system circuit, high conversion efficiency of 98.5% with 100-min stable operating capability has been demonstrated. In particular, rugged reliability is validated after over 1 million times dynamic breakdown with a 1.2-kV peak overvoltage. Meanwhile, superior device performance is achieved, including a static breakdown voltage (BV) of 1.95 kV, a dynamic BV of 2.23 kV, a forward current of 20 A (2 kA/cm2 current density), and a differential specific on -resistance of 1.9 mΩ·cm2. These results indicate that Ga2O3 power HJDs are developing rapidly with their own advantages, presenting the enormous potential in high-efficiency, high-power, and high-reliability applications.
TL;DR: In this paper , the phase distribution of the quasi-2D perovskite is finely controlled by mixing two different large organic cations, which effectively reduces the amount of smaller n-index phases.
Abstract: Perovskite light-emitting diodes (PeLEDs) have received great attention in recent years due to their narrow emission bandwidth and tunable emission spectrum. Efficient red emission is one of most important parts for lighting and displays. Quasi-2D perovskites can deliver high emission efficiency due to the strong carrier confinement, while the external quantum efficiencies (EQE) of red quasi-2D PeLEDs are inefficient at present, which is due to the complex distribution of different n-value phases in quasi-2D perovskite films. In this work, the phase distribution of the quasi-2D perovskite is finely controlled by mixing two different large organic cations, which effectively reduces the amount of smaller n-index phases, meanwhile the passivation of lead and halide defects in perovskite films is realized. Accordingly, the PeLEDs show 25.8% EQE and 1300 cd m−2 maximum brightness at 680 nm, which exhibits the highest performance for red PeLEDs up to now.
TL;DR: In this paper , a generalized Ginzburg-Landau model with higher-order terms in the momentum of the order parameter was applied to Rashba spin-orbit coupled systems, where analytical relations between the non-reciprocal critical currents and the system parameters were achieved.
Abstract: We study theoretically the superconductor diodes, where the magnitude of the critical current changes as the direction is reversed, in terms of a generalized Ginzburg-Landau model with the higher-order terms in the momentum of the order parameter. This theory is applied to Rashba spin-orbit coupled systems, where analytical relations between the nonreciprocal critical currents and the system parameters are achieved. Numerical calculations with mean-field theory are also obtained to study broader parameter regions. These results offer a rather general description and design principles of superconductor diodes.
TL;DR: In this article , the introduction of inorganic ligands in the antisolvents used in dot purification is reported in order to overcome the problem of instability in mixed-halide perovskites.
Abstract: Instability in mixed‐halide perovskites (MHPs) is a key issue limiting perovskite solar cells and light‐emitting diodes (LEDs). One form of instability arises during the processing of MHP quantum dots using an antisolvent to precipitate and purify the dots forming surface traps that lead to decreased luminescence, compromised colloidal stability, and emission broadening. Here, the introduction of inorganic ligands in the antisolvents used in dot purification is reported in order to overcome this problem. MHPs that are colloidally stable for over 1 year at 25 °C and 40% humidity are demonstrated and films that are stable under 100 W cm−2 photoirradiation, 4× longer than the best previously reported MHPs, are reported. In LEDs, the materials enable an EQE of 24.4% (average 22.5 ± 1.3%) and narrow emission (full‐width at half maximum of 30 nm). Sixfold‐enhanced operating stability relative to the most stable prior red perovskite LEDs having external quantum efficiency >20% is reported.
TL;DR: In this article , the authors demonstrate ultrastable and efficient near-infrared (~800 nm) perovskite light-emitting diodes with record-long operational lifetimes (T50, extrapolated) of 11,539 h (~1.3 years) and 32,675 h (~3.7 years) for initial radiance (or current densities) of 3.7 W sr−1 m−2 (~5.0 mA cm−2) and 2.1 Wsr−1m−2
Abstract: Perovskite light-emitting diodes are an emerging light source technology. However, similar to perovskite solar cells, poor operational stability remains an obstacle for commercial applications. Here we demonstrate ultrastable and efficient near-infrared (~800 nm) perovskite light-emitting diodes with record-long operational lifetimes (T50, extrapolated) of 11,539 h (~1.3 years) and 32,675 h (~3.7 years) for initial radiance (or current densities) of 3.7 W sr−1 m−2 (~5.0 mA cm−2) and 2.1 W sr−1 m−2 (~3.2 mA cm−2), respectively, with even longer lifetimes forecasted for lower radiance. Key to this stability is the introduction of a dipolar molecular stabilizer, which interacts with the cations and anions at the perovskite grain boundaries. This suppresses ion migration under electric fields, preventing the formation of lead iodide, which mediates the phase transformation and decomposition of α-FAPbI3 perovskite. These results remove the critical concern that halide perovskite devices may be intrinsically unstable, paving the path towards industrial applications. Near-infrared perovskite light-emitting diodes with extrapolated device lifespans on the scale of years are achieved by the use of a dipolar molecular stabilizer.
TL;DR: In this paper , the authors demonstrate ultrastable and efficient near-infrared (~800 nm) perovskite light-emitting diodes with record-long operational lifetimes (T50, extrapolated) of 11,539 h (~1.3 years) and 32,675 h (~3.7 years) for initial radiance (or current densities) of 3.7 W sr−1 m−2 (~5.0 mA cm−2) and 2.1 Wsr−1m−2
Abstract: Perovskite light-emitting diodes are an emerging light source technology. However, similar to perovskite solar cells, poor operational stability remains an obstacle for commercial applications. Here we demonstrate ultrastable and efficient near-infrared (~800 nm) perovskite light-emitting diodes with record-long operational lifetimes (T50, extrapolated) of 11,539 h (~1.3 years) and 32,675 h (~3.7 years) for initial radiance (or current densities) of 3.7 W sr−1 m−2 (~5.0 mA cm−2) and 2.1 W sr−1 m−2 (~3.2 mA cm−2), respectively, with even longer lifetimes forecasted for lower radiance. Key to this stability is the introduction of a dipolar molecular stabilizer, which interacts with the cations and anions at the perovskite grain boundaries. This suppresses ion migration under electric fields, preventing the formation of lead iodide, which mediates the phase transformation and decomposition of α-FAPbI3 perovskite. These results remove the critical concern that halide perovskite devices may be intrinsically unstable, paving the path towards industrial applications. Near-infrared perovskite light-emitting diodes with extrapolated device lifespans on the scale of years are achieved by the use of a dipolar molecular stabilizer.
TL;DR: In this article , the fundamental and engineering aspects of ion-related issues in perovskite light-emitting diodes (PeLEDs) are systematically discussed by considering the material and processing origins of ion generation, the mechanisms driving ion migration, characterization approaches for probing ion distributions, the effects of ion migration on device performance and stability, and strategies for ion management in PeLEDs.
Abstract: In recent years, perovskite light-emitting diodes (PeLEDs) have emerged as a promising new lighting technology with high external quantum efficiency, color purity, and wavelength tunability, as well as, low-temperature processability. However, the operational stability of PeLEDs is still insufficient for their commercialization. The generation and migration of ionic species in metal halide perovskites has been widely acknowledged as the primary factor causing the performance degradation of PeLEDs. Herein, this topic is systematically discussed by considering the fundamental and engineering aspects of ion-related issues in PeLEDs, including the material and processing origins of ion generation, the mechanisms driving ion migration, characterization approaches for probing ion distributions, the effects of ion migration on device performance and stability, and strategies for ion management in PeLEDs. Finally, perspectives on remaining challenges and future opportunities are highlighted.
TL;DR: In this paper , a p-NiO junction termination extension (JTE) and a small-angle beveled field plate (BFP) are proposed to improve the performance of heterojunction diodes.
Abstract: In this letter, high-performance p-NiO/ β -Ga 2 O 3 heterojunction diodes (HJDs) with composite terminal structures, a p-NiO junction termination extension (JTE), and a small-angle beveled field plate (BFP) are demonstrated. By implementing a p-NiO JTE structure, the optimal breakdown voltage ( V br ) of β -Ga 2 O 3 HJD increases from 955 to 1945 V, and the integration of the small-angle BFP further boosts the breakdown voltage up to 2410 V. An 80-nm thin p-NiO layer is adopted in the heterojunction to reduce the specific on -resistance ( R on,sp ), while the composite terminal structures have little effect on R on,sp , due to the super-large lateral spread resistance. The β -Ga 2 O 3 HJD with composite terminal structures achieves a low R on,sp of 1.12 mΩ·cm 2 , yielding the highest direct-current Baliga's figure-of-merit (FOM = V br 2 / R on,sp ) among all reported β-Ga 2 O 3 diodes with a value of 5.18 GW/cm 2 , which is about 15% of the theoretical value. These results suggest that the electrical field engineering with a composite terminal structure is a viable and effective technological strategy to enable the realization of β -Ga 2 O 3 bipolar power rectifiers.
TL;DR: In this paper , the thermally activated delayed fluorescence (TADF) mechanism can theoretically realize 100% internal quantum efficiency (IQE) through an effective upconversion process from nonradiative triplet excitons to radiative singlet ones.
Abstract: Nondoped organic light-emitting diodes (OLEDs) have drawn immense attention due to their merits of process simplicity, reduced fabrication cost, etc. To realize high-performance nondoped OLEDs, all electrogenerated excitons should be fully utilized. The thermally activated delayed fluorescence (TADF) mechanism can theoretically realize 100% internal quantum efficiency (IQE) through an effective upconversion process from nonradiative triplet excitons to radiative singlet ones. Nevertheless, exciton quenching, especially related to triplet excitons, is generally very serious in TADF-based nondoped OLEDs, significantly hindering the pace of development. Enormous efforts have been devoted to alleviating the annoying exciton quenching process, and a number of TADF materials for highly efficient nondoped devices have been reported. In this review, we mainly discuss the mechanism, exciton leaking channels, and reported molecular design strategies of TADF emitters for nondoped devices. We further classify their molecular structures depending on the functional A groups and offer an outlook on their future prospects. It is anticipated that this review can entice researchers to recognize the importance of TADF-based nondoped OLEDs and provide a possible guide for their future development.
TL;DR: In this paper , a new red-emitting SrLaScO4:Eu phosphor is designed, and the PLQY is enhanced from 13% to 67% under 450 nm excitation by employing (NH4)2SO4•assisted sintering.
Abstract: The discovery of Eu2+‐doped high‐efficiency red phosphors remains a vital challenge for white light‐emitting diode (WLED) applications. It is therefore urgent to find effective strategies managing the oxidation state to help reduce Eu3+ to Eu2+ and accordingly increase the photoluminescence quantum yield (PLQY). Herein, a new red‐emitting SrLaScO4:Eu phosphor is designed, and the PLQY is enhanced from 13% to 67% under 450 nm excitation by employing (NH4)2SO4‐assisted sintering. Combined structural analysis, optical spectroscopy, and theoretical calculation reveal that predominant Eu2+ prefers to occupy the Sr2+ sites in the SrLaScO4 enabling red emission, and a competitive site occupation of Eu3+ in La3+ can be restrained, and the reduction mechanism of Eu3+ to Eu2+ originating from the (NH4)2SO4 addition is analyzed. The fabricated WLED device using red‐emitting SrLaScO4:Eu and yellow‐emitting Y3(Al,Ga)5O12:Ce3+ exhibits a high color‐rendering index of 86.7 at a low correlated color temperature of 4005 K. This work provides a feasible reduction strategy for guiding the development of high‐efficiency Eu2+‐doped red phosphor for WLED applications.
TL;DR: In this article , a field-free superconducting diode effect (SDE) was demonstrated in a non-centrosymmetric NbV/Co/V/Ta superlattices with a polar structure.
Abstract: The diode effect is fundamental to electronic devices and is widely used in rectifiers and a.c.–d.c. converters. At low temperatures, however, conventional semiconductor diodes possess a high resistivity, which yields energy loss and heating during operation. The superconducting diode effect (SDE)1–8, which relies on broken inversion symmetry in a superconductor, may mitigate this obstacle: in one direction, a zero-resistance supercurrent can flow through the diode, but for the opposite direction of current flow, the device enters the normal state with ohmic resistance. The application of a magnetic field can induce SDE in Nb/V/Ta superlattices with a polar structure1,2, in superconducting devices with asymmetric patterning of pinning centres9 or in superconductor/ferromagnet hybrid devices with induced vortices10,11. The need for an external magnetic field limits their practical application. Recently, a field-free SDE was observed in a NbSe2/Nb3Br8/NbSe2 junction; it originates from asymmetric Josephson tunnelling that is induced by the Nb3Br8 barrier and the associated NbSe2/Nb3Br8 interfaces12. Here, we present another implementation of zero-field SDE using noncentrosymmetric [Nb/V/Co/V/Ta]20 multilayers. The magnetic layers provide the necessary symmetry breaking, and we can tune the SDE by adjusting the structural parameters, such as the constituent elements, film thickness, stacking order and number of repetitions. We control the polarity of the SDE through the magnetization direction of the ferromagnetic layers. Artificially stacked structures13–18, such as the one used in this work, are of particular interest as they are compatible with microfabrication techniques and can be integrated with devices such as Josephson junctions19–22. Energy-loss-free SDEs as presented in this work may therefore enable novel non-volatile memories and logic circuits with ultralow power consumption. Superconducting diodes, which can operate without dissipation losses at low temperature, usually require a magnetic field to function. A well-designed multilayer device now shows a reversible, non-volatile superconducting diode effect.
TL;DR: A high-performance Ni2+-doped garnet solid-solution broadband SWIR emitter is fabricated and a synergetic enhancement strategy, adding a fluxing agent and a charge compensator simultaneously, is proposed to deliver a more than 20-fold increase of the SWIR emission intensity and nearly 2-fold improvement of the thermal quenching behavior.
Abstract: Broadband shortwave infrared (SWIR) light-emitting diodes (LEDs), capable of advancing the next-generation solid-state smart invisible lighting technology, have sparked tremendous interest and will launch ground-breaking spectroscopy and instrumental applications. Nevertheless, the device performance is still suppressed by the low quantum efficiency and limited emission bandwidth of the critical phosphor layer. Herein, we report a high-performance Ni2+-doped garnet solid-solution broadband SWIR emitter centered at ∼1450 nm with a large full-width at half-maximum of ∼300 nm, thereby fabricating, for the first time, a directly excited Ni2+-doped garnet solid-solution phosphor-converted broadband SWIR LED device. A synergetic enhancement strategy, adding a fluxing agent and a charge compensator simultaneously, is proposed to deliver a more than 20-fold increase of the SWIR emission intensity and nearly 2-fold improvement of the thermal quenching behavior. The site occupation and mechanism behind the synergetic enhancement strategy are elucidated by a combination of experimental study and theoretical calculation. A prototype of the SWIR LED with a radiation flux of 1.25 mW is fabricated and utilized as an invisible SWIR light source to demonstrate the SWIR spectroscopy applications. This work not only opens a window to explore novel broadband SWIR phosphors but also provides a synergetic strategy to remarkably improve the performance of artificial SWIR LED light sources.
TL;DR: The key technological advancements and performance of these new-generation display devices, including virtual reality, augmented reality, quantum dot light-emitting diode, and organic light-embodied diode are discussed.
Abstract: The remarkable progress of virtual reality, augmented reality, quantum dot light-emitting diode, and organic light-emitting diode as next-generation displays has overcome the leadership of the liquid crystal display during the last two years. This paper discusses the key technological advancements and performance of these new-generation display devices.
TL;DR: In this paper , the performance evaluation and reliability validation at the system-level applications seriously limits their further development and even future commercialization, and a beveled-mesa NiO/Ga was implemented in a 500-W power factor correction (PFC) system circuit.
Abstract: The technical progress of Ga 2 O 3 power diodes is now stuck at a critical point where a lack of performance evaluation and reliability validation at the system-level applications seriously limits their further development and even future commercialization. In this letter, by implementing beveled-mesa NiO/Ga 2 O 3 p–n heterojunction diodes (HJDs) into a 500-W power factor correction (PFC) system circuit, high conversion efficiency of 98.5% with 100-min stable operating capability has been demonstrated. In particular, rugged reliability is validated after over 1 million times dynamic breakdown with a 1.2-kV peak overvoltage. Meanwhile, superior device performance is achieved, including a static breakdown voltage (BV) of 1.95 kV, a dynamic BV of 2.23 kV, a forward current of 20 A (2 kA/cm 2 current density), and a differential specific on -resistance of 1.9 mΩ·cm 2 . These results indicate that Ga 2 O 3 power HJDs are developing rapidly with their own advantages, presenting the enormous potential in high-efficiency, high-power, and high-reliability applications.
TL;DR: Based on the results of temperature-dependent electroluminescence and theoretical analysis, the authors revealed that holes can be successfully injected into quantum-dots via thermal-assisted thermionic-emission mechanism, thereby enabling the sub-bandgap turn-on and up-conversion electrolUMinescence of the devices.
Abstract: Up-conversion electroluminescence, in which the energy of a emitted photon is higher than that of the excitation electron, is observed in quantum-dot light-emitting diodes. Here, we study its mechanism by investigating the effect of thermal energy on the charge injection dynamic. Based on the results of temperature-dependent electroluminescence and theoretical analysis, we reveal that at sub-bandgap voltage, holes can be successfully injected into quantum-dots via thermal-assisted thermionic-emission mechanism, thereby enabling the sub-bandgap turn-on and up-conversion electroluminescence of the devices. Further theoretical deduction and experimental results confirm that thermal-assisted hole-injection is the universal mechanism responsible for the up-conversion electroluminescence. This work uncovers the charge injection process and unlocks the sub-bandgap turn-on mechanism, which paves the road for the development of up-conversion devices with power conversion efficiency over 100%.