Metal halide perovskite materials are an emerging class of solution-processable semiconductors with considerable potential for use in optoelectronic devices1–3. For example, light-emitting diodes (LEDs) based on these materials could see application in flat-panel displays and solid-state lighting, owing to their potential to be made at low cost via facile solution processing, and could provide tunable colours and narrow emission line widths at high photoluminescence quantum yields4–8. However, the highest reported external quantum efficiencies of green- and red-light-emitting perovskite LEDs are around 14 per cent7,9 and 12 per cent8, respectively—still well behind the performance of organic LEDs10–12 and inorganic quantum dot LEDs13. Here we describe visible-light-emitting perovskite LEDs that surpass the quantum efficiency milestone of 20 per cent. This achievement stems from a new strategy for managing the compositional distribution in the device—an approach that simultaneously provides high luminescence and balanced charge injection. Specifically, we mixed a presynthesized CsPbBr3 perovskite with a MABr additive (where MA is CH3NH3), the differing solubilities of which yield sequential crystallization into a CsPbBr3/MABr quasi-core/shell structure. The MABr shell passivates the nonradiative defects that would otherwise be present in CsPbBr3 crystals, boosting the photoluminescence quantum efficiency, while the MABr capping layer enables balanced charge injection. The resulting 20.3 per cent external quantum efficiency represents a substantial step towards the practical application of perovskite LEDs in lighting and display. A strategy for managing the compositional distribution in metal halide perovskite light-emitting diodes enables them to surpass 20% external quantum efficiency—a step towards their practical application in lighting and displays.

/pdf/perovskite-light-emitting-diodes-with-external-quantum-4xijmv6ocq.pdf

Perovskite light-emitting diodes with external quantum efficiency exceeding 20 per cent

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.

Quantum Dot Light-Emitting Diodes Based on Inorganic Perovskite Cesium Lead Halides (CsPbX3)

A single-junction polymer solar cell with an efficiency of 10.1% is demonstrated by using deterministic aperiodic nanostructures for broadband light harvesting with optimum charge extraction. The performance enhancement is ascribed to the self-enhanced absorption due to collective effects, including pattern-induced anti-reflection and light scattering, as well as surface plasmonic resonance, together with a minimized recombination probability.

Single-Junction Polymer Solar Cells Exceeding 10% Power Conversion Efficiency

Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjug...

Organic Optoelectronic Materials: Mechanisms and Applications

Solution-processed CsPbBr3 quantum-dot light-emitting diodes with a 50-fold external quantum efficiency improvement (up to 6.27%) are achieved through balancing surface passivation and carrier injection via ligand density control (treating with hexane/ethyl acetate mixed solvent), which induces the coexistence of high levels of ink stability, photoluminescence quantum yields, thin-film uniformity, and carrier-injection efficiency.

50-Fold EQE Improvement up to 6.27% of Solution-Processed All-Inorganic Perovskite CsPbBr3 QLEDs via Surface Ligand Density Control

The invention belongs to the technical field of display application and provides a light intensity modulator. The light intensity modulator comprises a first electrode, a planar optical waveguide, a second electrode, a coupling module and a decoupling module, and the planar optical waveguide comprises at least one quantum dot layer and at least one dielectric layer which are stacked and combined.The electro-absorption efficiency of a quantum dot material in the quantum dot layer is one magnitude order higher than that of a body material of the same material, so that the electro-absorption efficiency of the light intensity modulator is greatly improved. Meanwhile, by using the stacked quantum dot layer and the dielectric layer, control over refractive index distribution in the waveguide can be effectively improved, so that the tolerance of the waveguide to a light guide mode is reduced, and the light intensity modulation efficiency is improved.

Light intensity modulator

The light extraction efficiency in organic light-emitting devices was enhanced using polymer microlens arrays fabricated by a soft lithography method. A maximum of 2.6-fold increase in efficiency was achieved in the top-emitting device geometry.

Enhancing OLED Light Extraction with Polymer Microlens Arrays

The invention provides a preparation method of a functional layer of a QLED device. The method comprises the following steps of providing a pre-patterned pixel channel; providing inkjet printing equipment provided with two nozzles for containing functional layer ink and solvent vapor separately; and firstly spraying and dripping functional layer ink droplets on a substrate layer of the pixel channel through one spray head, then spraying the solvent vapor on the surfaces of the functional layer ink droplets through the other spray head and carrying out drying and film forming to prepare a functional layer, wherein the functional layer comprises a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and an electron injection layer; thefunctional layer ink comprises a functional layer material and an ink solvent; the flow of the solvent vapor meets the condition that local bias pressure is greater than vapor pressure at corresponding temperature; a solvent used for the solvent vapor meets the condition that the liquid phase surface tension of the solvent is smaller than that of the ink solvent; the solvent vapor and the ink solvent are mutually dissolved; and the functional layer material can be dissolved.

Preparation method of functional layer of QLED device

The invention discloses a cross-linked nanoparticle film and amanufacturing method thereof, and a thin film optoelectronic device The method comprises the following steps of dispersing nanoparticlesin a solvent, stirring uniformly and acquiring a nanoparticle solution; and through a solution method, manufacturing the nanoparticle solution into a nanoparticle film, injecting a combined gas to urge cross-linked reaction generation, and acquiring the cross-linked nanoparticle film In the invention, when the nanoparticles form a film, the combined gas is injected so that the particles are urgedto carry out mutual crosslinking Therefore, the electrical coupling among the particles is increased, the barrier of carrier transmission is reduced, a carrier mobility is increased, and electric performance is greatly improved

Cross-linked nanoparticle film and manufacturing method thereof, and thin film optoelectronic device

A p-i-n structure-based QLED device, comprising a substrate (10), a bottom electrode (20), a hole transport layer (30), an electron blocking layer (40), a quantum dot light emitting layer (50), a hole blocking layer (60), an electron transport layer (70), and a top electrode (80). On one hand, a p-type material is used as a hole transport layer and an n-type material is used as an electron transport layer to reduce a driving voltage of the QLED device, thereby effectively reduce the quenching of quantum dot light emitting due to the Stark effect. On the other hand, an intrinsic matrix material (100) is introduced into a quantum dot light emitting layer to reduce the cross relaxation between quantum dots (90) and to increase the probability of radiative recombination; meanwhile, injected electrons and holes can further be effectively trapped to improve the current efficiency, thereby improving the light emitting efficiency of the device and increasing the service life and the stability of the device.

Cao Weiran

Papers

Light intensity modulator

Enhancing OLED Light Extraction with Polymer Microlens Arrays

Preparation method of functional layer of QLED device

Cross-linked nanoparticle film and manufacturing method thereof, and thin film optoelectronic device

P-i-n structure-based qled device and manufacturing method therefor