Perovskite quantum-dot-based light-emitting diodes (QLEDs) possess the features of wide gamut and real color expression, which have been considered as candidates for high-quality lightings and ...displays. However, massive defects are prone to be reproduced during the quantum dot (QD) film assembly, which would sorely affect carrier injection, transportation and recombination, and finally degrade QLED performances. Here, we propose a bilateral passivation strategy through passivating both top and bottom interfaces of QD film with organic molecules, which has drastically enhanced the efficiency and stability of perovskite QLEDs. Various molecules were applied, and comparison experiments were conducted to verify the necessity of passivation on both interfaces. Eventually, the passivated device achieves a maximum external quantum efficiency (EQE) of 18.7% and current efficiency of 75 cd A
. Moreover, the operational lifetime of QLEDs is enhanced by 20-fold, reaching 15.8 h. These findings highlight the importance of interface passivation for efficient and stable QD-based optoelectronic devices.
Halide perovskite quantum dots (Pe‐QDs) have been considered as outstanding candidates for photodetector, light‐emitting diode, and lasing applications, but these perspectives are being impeded by ...the severe stability, including both chemical and optical degradations. This study reports on amino‐mediated anchoring Pe‐QDs onto the surfaces of monodisperse silica to effectively depress the optical degradation of their photoluminescence (PL) and random lasing stabilities, hence achieving highly stable and low‐threshold lasing. An amination‐mediated nucleation and growth process is designed for the general and one‐pot synthesis of Pe‐QDs on the surfaces of silica spheres. The facile synthetic process, which can be finished within several minutes, insures scalable production. Surprisingly, almost no PL degradation is observed after 40 d storage under ambient conditions, even 80% PL intensity can be maintained after persistently illuminated by UV lamps for 108 h. Subsequently, extremely stable random lasing is achieved after storage for 2 months or over continuously optical pumping for 8 h. Such high PL and lasing stabilities originate from the isolation effects due to the effective anchoring, which separate the Pe‐QDs from each other and inhibit the photoinduced regrowth and deterioration. This work will also open the window of perovskite‐based multifunctional systems.
Amino‐mediated anchoring of perovskite quantum dots (QDs) onto the surfaces of monodisperse silica spheres separates the QDs from each other and inhibits the photoinduced regrowth and deterioration effectively, which also contributes to highly stable and low‐threshold random lasing. The general and one‐pot synthetic procedures ensure scalable production and open the window of perovskite‐based multifunctional systems.
At present, electric lighting accounts for ~15% of global power consumption and thus the adoption of efficient, low-cost lighting technologies is important. Halide perovskites have been shown to be ...good emitters of pure red, green and blue light, but an efficient source of broadband white electroluminescence suitable for lighting applications is desirable. Here, we report a white light-emitting diode (LED) strategy based on solution-processed heterophase halide perovskites that, unlike GaN white LEDs, feature only one broadband emissive layer and no phosphor. Our LEDs operate with a peak luminance of 12,200 cd m−2 at a bias of 6.6 V and a maximum external quantum efficiency of 6.5% at a current density of 8.3 mA cm−2. Systematic in situ and ex situ characterizations reveal that the mechanism of efficient electroluminescence is charge injection into the α phase of CsPbI3, α to δ charge transfer and α–δ balanced radiative recombination. Future advances in fabrication technology and mechanistic understanding should lead to further improvements in device efficiency and luminance.Heterophase CsPbI3 perovskite gives rise to bright white phosphor-free LEDs.
The typical two‐dimensional (2D) semiconductors MoS2, MoSe2, WS2, WSe2 and black phosphorus have garnered tremendous interest for their unique electronic, optical, and chemical properties. However, ...all 2D semiconductors reported thus far feature band gaps that are smaller than 2.0 eV, which has greatly restricted their applications, especially in optoelectronic devices with photoresponse in the blue and UV range. Novel 2D mono‐elemental semiconductors, namely monolayered arsenene and antimonene, with wide band gaps and high stability were now developed based on first‐principles calculations. Interestingly, although As and Sb are typically semimetals in the bulk, they are transformed into indirect semiconductors with band gaps of 2.49 and 2.28 eV when thinned to one atomic layer. Significantly, under small biaxial strain, these materials were transformed from indirect into direct band‐gap semiconductors. Such dramatic changes in the electronic structure could pave the way for transistors with high on/off ratios, optoelectronic devices working under blue or UV light, and mechanical sensors based on new 2D crystals.
Unlike black phosphorus, both arsenic and antimony are typical semimetals in their natural, layered bulk state. However, monolayered arsenene and antimonene are indirect wide‐band‐gap semiconductors, and under strain, they become direct band‐gap semiconductors. Owing to these band‐gap transitions, these materials could find applications in nano‐ and optoelectronic devices.
As new members of carbon material family, carbon and graphene quantum dots (CDs, GQDs) have attracted tremendous attentions for their potentials for biological, optoelectronic, and energy related ...applications. Among these applications, bio‐imaging has been intensively studied, but optoelectronic and energy devices are rapidly rising. In this Feature Article, recent exciting progresses on CD‐ and GQD‐based optoelectronic and energy devices, such as light emitting diodes (LEDs), solar cells (SCs), photodetctors (PDs), photocatalysis, batteries, and supercapacitors are highlighted. The recent understanding on their microstructure and optical properties are briefly introduced in the first part. Some important progresses on optoelectronic and energy devices are then addressed as the main part of this Feature Article. Finally, a brief outlook is given, pointing out that CDs and GQDs could play more important roles in communication‐ and energy‐functional devices in the near future.
Carbon dots and graphene quantum dots have been investigated for several years and researchers' interest is moving from photoluminescence towards device applications. In this Feature Article, applications in optoelectronic and energy devices of carbon dots and graphene quantum dots are summarized, as well as their optical properties. Future directions, challenges, and other possible applications are also put forward.
Carbon neutrality, energy savings, and lighting costs and quality have always led to urgent demand for lighting technology innovation. White light-emitting diodes (WLEDs) based on a single emissive ...layer (SEL) fabricated by the solution method have been continuously researched in recent years; they are advantageous because they have a low cost and are ultrathin and flexible. Here, we reviewed the history and development of SEL-WLEDs over recent years to provide inspiration and promote their progress in lighting applications. We first introduced the emitters and analysed the advantages of these emitters in creating SEL-WLEDs and then reviewed some cases that involve the above emitters, which were formed via vacuum thermal evaporation or solution processes. Some notable developments that deserve attention are highlighted in this review due to their potential use in SEL-WLEDs, such as perovskite materials. Finally, we looked at future development trends of SEL-WLEDs and proposed potential research directions.
As the development of oxygen evolution co-catalysts (OECs) is being actively undertaken, the tailored integration of those OECs with photoanodes is expected to be a plausible avenue for achieving ...highly efficient solar-assisted water splitting. Here, we demonstrate that a black phosphorene (BP) layer, inserted between the OEC and BiVO
can improve the photoelectrochemical performance of pre-optimized OEC/BiVO
(OEC: NiOOH, MnO
and CoOOH) systems by 1.2∼1.6-fold, while the OEC overlayer, in turn, can suppress BP self-oxidation to achieve a high durability. A photocurrent density of 4.48 mA·cm
at 1.23 V vs reversible hydrogen electrode (RHE) is achieved by the NiOOH/BP/BiVO
photoanode. It is found that the intrinsic p-type BP can boost hole extraction from BiVO
and prolong holes trapping lifetime on BiVO
surface. This work sheds light on the design of BP-based devices for application in solar to fuel conversion, and also suggests a promising nexus between semiconductor and electrocatalyst.
Recently, Kovalenko and co‐workers and Li and co‐workers developed CsPbX3 (X = Cl, Br, I) inorganic perovskite quantum dots (IPQDs), which exhibited ultrahigh photoluminescence (PL) quantum yields ...(QYs), low‐threshold lasing, and multicolor electroluminescence. However, the usual synthesis needs high temperature, inert gas protection, and localized injection operation, which are severely against applications. Moreover, the so unexpectedly high QYs are very confusing. Here, for the first time, the IPQDs' room‐temperature (RT) synthesis, superior PL, underlying origins and potentials in lighting and displays are reported. The synthesis is designed according to supersaturated recrystallization (SR), which is operated at RT, within few seconds, free from inert gas and injection operation. Although formed at RT, IPQDs' PLs have QYs of 80%, 95%, 70%, and FWHMs of 35, 20, and 18 nm for red, green, and blue emissions. As to the origins, the observed 40 meV exciton binding energy, halogen self‐passivation effect, and CsPbX3@X quantum‐well band alignment are proposed to guarantee the excitons generation and high‐rate radiative recombination at RT. Moreover, such superior optical merits endow them with promising potentials in lighting and displays, which are primarily demonstrated by the white light‐emitting diodes with tunable color temperature and wide color gamut.
A room‐temperature supersaturated recrystallization method is developed to rapidly synthesize all‐inorganic halide perovskite QDs with blue, green, and red luminescent quantum yields of 70%–95% and line‐widths less than 35 nm. The origins of the optical superiority are proposed to be the observed 40 meV exciton binding energy, surface self‐passivation effect, and quantum‐well band alignment. Such superior optical merits endow them with promising potentials in healthy lighting and wide‐color‐gamut displays, which are primarily demonstrated by the color‐temperature‐tunable white light‐emitting diodes.
Novel quantum‐dot light‐emitting diodes based on all‐inorganic perovskite CsPbX3 (X = Cl, Br, I) nanocrystals are reported. The well‐dispersed, single‐crystal quantum dots (QDs) exhibit high quantum ...yields, and tunable light emission wavelength. The demonstration of these novel perovskite QDs opens a new avenue toward designing optoelectronic devices, such as displays, photodetectors, solar cells, and lasers.
2D phosphorene, arsenene, antimonene, and bismuthene, as a fast‐growing family of 2D monoelemental materials, have attracted enormous interest in the scientific community owing to their intriguing ...structures and extraordinary electronic properties. Tuning the monoelemental crystals into bielemental ones between group‐VA elements is able to preserve their advantages of unique structures, modulate their properties, and further expand their multifunctional applications. Herein, a review of the historical work is provided for both theoretical predictions and experimental advances of 2D V‐V binary materials. Their various intriguing electronic properties are discussed, including band structure, carrier mobility, Rashba effect, and topological state. An emphasis is also given to their progress in fabricated approaches and potential applications. Finally, a detailed presentation on the opportunities and challenges in the future development of 2D V‐V binary materials is given.
2D V‐V binary materials, as the internal combination of group‐VA elements (N, P, As, Sb, Bi), have become a popular research topic. Through the interaction among charge, orbital, lattice, and spin degrees of freedom, the favorable and superior properties in 2D V‐V binary materials can be further modulated, extending their application in novel electronic, optoelectronic, and energy devices.
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