Inverted blue light quantum-dot thin film electroluminescence device and manufacturing method thereof

Abstract

An inverted blue light quantum-dot thin film electroluminescence device disclosed by the present invention comprises a substrate, a cathode, an electronic transmission layer, a blue light quantum-dot luminescent layer, hole transport layers and an anode which are laminated orderly, and the hole transport layers comprise a third hole transport layer, a second hole transport layer and a first hole transport layer which are laminated orderly. The thickness of the third hole transport layer is between 5 nm and 10 nm, and the HOMO energy level of the second hole transport layer is greater than the HOMO energy level of the first hole transport layer, thereby forming the ladder-like potential barrier between the blue light quantum-dot luminescent layer and the anode, improving the hole-injection ability of the hole transport layers gradually, and satisfying the hole injection requirement of the blue light quantum-dot thin film electroluminescence device. The electroluminescence device of the present invention is low in hole injection barrier and high in carrier direct injection mechanism and luminous efficiency. The present invention also provides a method for preparing the above inverted blue light quantum-dot thin film electroluminescence device.

Description

technical field [0001] The invention relates to the technical field of electroluminescent devices, in particular to an inverted blue light quantum dot thin film electroluminescent device and a manufacturing method thereof. Background technique [0002] Semiconductor quantum dots (QDs, Quantum Dots) materials with a diameter between 2nm and 10nm belong to quasi-zero-dimensional nanomaterials, also known as nanocrystals. Since 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 radius is equal or smaller, the localization and coherence of electrons are enhanced, the absorption coefficient of the exciton band increases, strong absorption of excitons occurs, strong fluorescence can be emitted after excitation, and it has a narrow and symmetrical emission spectrum, wide and continuous Absorptio...

AI Technical Summary

Problems solved by technology

[0005] The QLEDs devices in the prior art have the following problems: the main problem of the QLED devices prepared by the core-shell structure CdSe@ZnS material is that the highest molecular orbital position (HOMO, Highest Occupied Molecular Orbital) of the QDs material itself is relatively high ( >6.0eV), especially for green and blue QDs, their HOMO energy levels are greater than 6.5eV, while the HOMO energy levels of commonly used hole transport materials are generally between 5.5eV and 6.0eV, which results in QLEDs devices The higher hole injection barrier restricts the process of direct carrier injection to form excitons. At the same time, QDs have a wide and continuous absorption spectrum that makes it easy to absorb external energy to form excitons. Therefore, the light-emitting excitons in QLEDs The formation of carriers is mainly affected by the joint action of two mechanisms: direct carrier injection and energy transfer.

The improvement of direct carrier injection will generally enhance the luminous efficiency of QLEDs devices; and the energy transfer mechanism is generally carried out from high energy gap materials to low energy gap materials. Therefore, for high energy gap blue light and green light, the energy transfer mechanism The occurrence of often restricts the improvement of its luminous efficiency

Images