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Breaking the theoretical limits of external quantum efficiency (EQE) and obtaining quantum dot light‐emitting diodes (QLEDs) with high brightness, high efficiency, and low operating voltage is the basis of commercial applications in display and illumination. Devices with an EQE of over 20% can be realized by carrier equilibrium injection and light out‐coupling enhancement. However, it is difficult to synergistically enhance the performance of QLEDs by combining the light out‐coupling and the hole enhancement injection. In this paper, the injection enhancement of holes and the light out‐coupling are realized simultaneously only by nano‐imprint lithography (NIL). The π─π bonds of the PEDOT: PSS film treated by NIL demonstrate a molecular orientation perpendicular to the substrate, which improves the injection of the hole. The PEDOT: PSS patterned by NIL further presents improved light out‐coupling. Consequently, the EQE of red‐QLED is 30.42% with a synergistic enhancement factor of 61%, accompanying the maximum brightness increased by 8% to 125 200 cd m−2 at 4.6 V (Vturn‐on, 1.74 V). The EQE and brightness of green‐QLED increased by 38.9% and 34.3% to 24.16% and 279 700 cd m−2, respectively. Therefore, NIL will provide new insights into synergistically enhancing light out‐coupling and internal quantum efficiency to break through the performance of electroluminescence (EL). [ABSTRACT FROM AUTHOR]

The low hole injection efficiency severely constrains the operational capability of blue quantum‐dot light‐emitting diodes (QLEDs). Constructing the structure of stepped energy levels is an effective approach to enhance the hole injection efficiency. Here, the dual hole injection structure is fabricated through the introduction of Ti3C2Tx film, in which its function is modulated by controlling the size of Ti3C2Tx nanosheets. Benefitting from a matched Fermi energy of Ti3C2Tx film, the Ti3C2Tx‐modified devices achieve a peak external quantum efficiency (EQE) of 15.89%, exhibiting a 67% increase compared to the reference devices with an EQE of 9.72%. The enhanced EQE can be attributed to the reduced energy barrier between indium tin oxide (ITO) and PEDOT:PSS, resulting from the incorporation of a Ti3C2Tx hole injection layer. In addition, the Ti3C2Tx layer effectively avoids the corrosion of the ITO electrode by acidic PEDOT:PSS, thereby enhancing the electrical stability of the ITO/PEDOT:PSS interface. The results provide a new approach to realize the high‐performance blue QLEDs devices. [ABSTRACT FROM AUTHOR]

Quantum‐dot light‐emitting diodes (QLEDs) are proposed as one of the most promising candidates for next‐generation displays, but their commercial application is seriously limited due to the poor performance of blue QLEDs (B‐QLEDs). Herein, this work uses Ti3C2Tx nanosheets to tune the work function (WF) of ZnMgO and to engineer the quantum dot (QD)/electron transport layer (ETL) interface. The B‐QLEDs with ZnMgO‐Ti3C2Tx hybrid ETL exhibit a maximum EQE of 15.81% and a remarkable T50 operation lifetime of 3284 h at 100 cd m−2. In addition to that, ultraviolet photoemission spectroscopy and density functional theory calculations both confirm that the addition of Ti3C2Tx to ZnMgO can effectively tune the ZnMgO's work function, further give rise to the reduction of QD/ETL energy barrier, which finally results in the alleviation of charge accumulation at the QD/ETL interface. The findings of interface engineering by Ti3C2Tx not only provide a promising strategy for the application of 2D materials in optoelectronic devices, but also pave the way to construct high‐performance light‐emitting diodes. [ABSTRACT FROM AUTHOR]

Quantum dot light‐emitting diodes (QLEDs), based on the solution‐processable colloidal quantum dots (QDs), are the high potential candidate for next generation display and lighting due to their high color purity, wide color gamut, low power consumption, and wide angle of view. Efforts have been made to improve the performance of the devices in order to achieve the goals of practical applications. This review focuses on the research progress in the materials and device physics of QLEDs, with the aims to accelerate the process of overcoming the obstacles to commercialization. Herein, the unique optical properties of QDs and the evolution of device structures are first reviewed. Then carrier dynamics, which has a decisive impact on device performance, is discussed in detail. In addition, the main obstacle to commercialization is emphasized as device stability, including operational stability, shelf stability, and efficiency roll‐off. Finally, unresolved issues in device physics are discussed, along with suggestions for future research directions. This review is expected to encourage further research in device physics and promote the development of QLEDs in the field of display and solid‐state lighting. [ABSTRACT FROM AUTHOR]

The article in Advanced Optical Materials discusses the successful suppression of defects in Te-doped Cs2ZrCl6 perovskite nanoparticles, resulting in highly efficient and thermally stable white light-emitting diodes. The nanoparticles were designed with a high photoluminescence quantum yield of up to 96% through crystallization and surface control. The white light-emitting diodes based on these nanoparticles achieved a color coordinate of (0.31, 0.33) and a color rendering index of 86. The research was conducted by a team from Henan University. [Extracted from the article]

The brightness of white quantum dot light‐emitting diodes (W‐QLEDs) is one of the most important indicators for their commercialization. However, the brightness of W‐QLEDs is severely limited by the light trapped in the substrate mode. In this work, a prototype W‐QLED with the original brightness of 88 181 cd m−2 is fabricated by using a mixture of red‐, green‐, and blue‐emitting quantum dots as a light emitting layer. Then, a tailored wrinkle pattern is attached on the bottom of the glass substrate of W‐QLEDs for the further light extraction. Different from the widely used external periodic patterns, the wrinkle patterns with richer Fourier spectra can outcouple the tricolor light trapped in the substrate mode simultaneously. In this case, the brightness of W‐QLEDs has a 54.4% enhancement to an ultra‐high value 136 207 cd m−2, and realizes the quasi‐Lambertian emission. The external quantum efficiency is improved from 9.68% to 13.41%. Meanwhile, correlated color‐temperature can cover a wider span transforming from pure white light (5115 K) to cold white light (6912 K). This work proposes a unique and efficient approach for the light extraction and color control of W‐QLEDs for their real application. [ABSTRACT FROM AUTHOR]

Nickel oxide (NiO), as a kind of p-type transition metal oxide (TMO) has shown promising applications in photoelectric devices. In our work, the NiO nanocrystals (NCs) are fabricated by a simple solvothermal method using tert-butyl alcohol and nickel acetylacetonate as precursors at 200 °C for different reaction times. The diameters and valence band edge of the prepared NiO NCs are increased with the increase reaction time from 12 h, 24 h–36 h. The band gaps of the NiO NCs were decreased with the increase time. Selected area electron diffraction (SAED) shows that the NiO NCs is polycrystalline structure. X-ray diffraction (XRD) indicates that the NiO NCs is cubic crystal form. X-ray photoelectron spectroscopy (XPS) shows that the as-prepared NiO NCs have a core of NiO and some form of Ni 2 O 3 and NiOOH states on its surface. Further, the obtained NiO NCs is applied on quantum dot light-emitting diode (QLED) as hole injection layer (HILs), showing excellent hole injection properties. Particularly, the NiO NCs for 24 h obtains the best results due to its high band gap and pure cubic crystal phase. Highly bright orange-red QLED with peak luminance up to ∼25580 cd m −2 , and current efficiency (CE) of 5.38 cd A −1 are achieved successfully based on the high performance NiO HIL, further, the device obtained relative long operational lifetime of 11491 h, which has been improved by more than 6- fold as compared to 1839 h for the device based on PEDOT. [ABSTRACT FROM AUTHOR]

The low hole injection efficiency severely constrains the operational capability of blue quantum‐dot light‐emitting diodes (QLEDs). Constructing the structure of stepped energy levels is an effective approach to enhance the hole injection efficiency. Here, the dual hole injection structure is fabricated through the introduction of Ti3C2Tx film, in which its function is modulated by controlling the size of Ti3C2Tx nanosheets. Benefitting from a matched Fermi energy of Ti3C2Tx film, the Ti3C2Tx‐modified devices achieve a peak external quantum efficiency (EQE) of 15.89%, exhibiting a 67% increase compared to the reference devices with an EQE of 9.72%. The enhanced EQE can be attributed to the reduced energy barrier between indium tin oxide (ITO) and PEDOT:PSS, resulting from the incorporation of a Ti3C2Tx hole injection layer. In addition, the Ti3C2Tx layer effectively avoids the corrosion of the ITO electrode by acidic PEDOT:PSS, thereby enhancing the electrical stability of the ITO/PEDOT:PSS interface. The results provide a new approach to realize the high‐performance blue QLEDs devices. [ABSTRACT FROM AUTHOR]