Inverted Blue Quantum Dot Thin Film Electroluminescent Device

Abstract

The invention discloses an inverted blue light quantum dot thin film electroluminescent device, which comprises a substrate, a cathode, an electron transport layer, a blue light quantum dot luminescent layer, a hole balance layer, a hole transport layer and an anode stacked in sequence. The hole transport layer includes a third hole transport layer, a second hole transport layer and a first hole transport layer stacked in sequence. The thickness of the hole balancing layer is 5nm˜10nm. The HOMO energy levels of the third hole transport layer, the second hole transport layer, and the first hole transport layer decrease sequentially, thereby forming a stepped barrier between the blue light quantum dot light-emitting layer and the anode to gradually increase the hole density. The hole injection capability of the transport layer meets the hole injection requirements of blue light quantum dot thin film electroluminescent devices. Further, the hole balance layer can prevent the direct contact between the high-mobility first hole transport material and the blue light quantum dot light-emitting layer, so as to avoid luminescence quenching.

Description

technical field [0001] The invention relates to the technical field of light-emitting devices, in particular to an electroluminescent device with an inverted blue quantum dot thin film. Background technique [0002] Quantum dots (QDs, quantum dots) are some extremely small semiconductor nanocrystals that cannot be seen by the naked eye, and the particle size is generally less than 10nm. When stimulated by light or electricity, quantum dots can emit colored light. The color of light is determined by the composition, material, size and shape of quantum dots. This feature enables quantum dots to change the color of light emitted by the light source. Because electrons, holes, and excitons are quantum-confined in the three-dimensional direction, the energy band structure of QDs changes from a bulk continuous structure to a discrete energy level structure with molecular characteristics. When the particle size of QDs is equal to or smaller than the Bohr radius of Wannier excitons ...

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Problems solved by technology

[0003] However, holes in traditional quantum dot thin film electroluminescent devices (QLED) are not easy to inject, and hole injection materials with high HOMO (Highest Occupied Molecular Orbital, highest occupied molecular orbital) energy level are needed to help hole injection

Especially for blue light quantum dot thin film electroluminescent devices, the HOMO energy level of blue light quantum dots is generally large, about 6.8eV, while the work function of general transparent anodes is less than 5.0eV, the difference between the two is far, resulting in QLED The hole injection barrier in the device is generally high, and the HOMO energy level of commonly used hole injection materials is generally 5.0eV ~ 5.5eV, which cannot meet the requirements of hole injection.

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