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.

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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 discloses a thin film transistor and a manufacturing method thereof. The semiconductor layer material of the thin film transistor is a cross-linked nano-particle film formed through carrying out crosslinking treatment on a nanoparticle film. The cross-linked nano-particle film is applied in the semiconductor layer of the thin film transistor so that a hot carrier effect can be effectively reduced and the performance of the thin film transistor is greatly increased.

Thin film transistor and manufacturing method thereof

44.4: Invited Paper: Study on the Degradation Mechanisms of Quantum‐Dot Light‐Emitting Diodes

The invention discloses an electroluminescent device and a manufacturing method thereof. The method comprises the following steps of step A, depositing a hole injection layer on a first electrode; step B, depositing a hole transporting layer on the hole injection layer; step C, depositing a luminescent layer on the hole transporting layer; step D, depositing an electron transporting layer on the luminescent layer, wherein the material of the electron transporting layer is a cross-linked nano-particle film formed through carrying out crosslinking treatment on a nanoparticle film; and step E, evaporating a second electrode on the luminescent layer and acquiring the electroluminescent device. In the invention, the acquired cross-linked nano-particle film is applied in the electroluminescent device manufactured through a solution method, the amount of an electron current injected into the luminescent layer under a same condition can be greatly increased, which is good for improving carrierbalance in the electroluminescent device, and then, the luminescence efficiency of the device is increased and the service life of the device is prolonged.

Electroluminescent device and manufacturing method thereof

본 발명은 가교 나노입자 박막 및 그의 제조방법과 박막 광전자 소자를 개시하였다. 그 중, 제조방법은 나노입자를 용매에 분산시키고 고르게 혼합하여 나노입자 용액을 획득하는 단계; 용액법을 통해 나노입자 용액을 나노입자 박막으로 제조하고, 조성 가스를 통입하여 가교반응의 발생을 촉진시킴으로써 가교 나노입자 박막을 획득하는 단계를 포함한다. 나노입자로 막을 형성 시, 조성 가스를 통입하여 입자 간의 상호 가교를 촉진시킴으로써 입자 간의 전기적 결합을 증가시키고, 캐리어 수송의 전위 장벽을 낮추어 캐리어 이동도를 증가시키며, 이에 따라 박막의 전기적 성능이 대폭 향상된다.

가교 나노 입자 박막 및 제조방법과 박막 광전자 소자

The invention discloses a four-footed quantum dot and a preparation method thereof. The method includes the steps that (A) under inert gas atmosphere, a zinc precursor is heated and then is injected into a InP quantum dot solution, then a sulfur precursor is injected to the InP quantum dot solution, and reaction is performed for 5-120 minutes to obtain a reaction solution; (B) after the reaction solution is cooled to room temperature, the product is repeatedly dissolved, precipitated and centrifugally purified, and the InP/ZnS four-footed quantum dot with a core-shell structure is obtained. The InP/ZnS four-footed quantum dot prepared by adopting the method is controllable in crystal type and size, holes are bound in the three-dimensional direction, and electrons are bound in the two-dimensional direction. In addition, the quantum dot structure can effectively improve the luminous efficiency, accordingly can be used as luminescent materials for photoelectric and electroluminescent devices.

Cao Weiran

Papers

Thin film transistor and manufacturing method thereof

44.4: Invited Paper: Study on the Degradation Mechanisms of Quantum‐Dot Light‐Emitting Diodes

Electroluminescent device and manufacturing method thereof

가교 나노 입자 박막 및 제조방법과 박막 광전자 소자

Four-footed quantum dot and preparation method thereof