Light-Emitting Device Inorganic Oxide Refractive Index Control
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Solution Overview
Problem
Organic light-emitting devices face challenges in achieving long lifespan blue color coordinates with short wavelength and adjusting color coordinates while maintaining high quantum efficiency.
Innovation Solution
A light-emitting device structure is implemented with specific refractive index relationships between layers, including an oxide of an inorganic compound, to enhance quantum efficiency by controlling light intensity, featuring a first electrode, a second electrode, and an interlayer with layers A, B, and C, where refractive indices satisfy certain equations, and the interlayer includes a capping layer, hole transport region, and electron transport region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an optical cavity is formed using only organic material layers, electrodes, and capping layers, then the device structure is simple, but blue color coordinates with long lifespan cannot be achieved
Solution Approach 1:
The patent introduces inorganic oxide layers (layers A, B, and C) to form a composite structure with organic emission layers. This composite approach enables achievement of blue color coordinates with long lifespan while maintaining reasonable device structure, resolving the contradiction between structural simplicity and color stability.
2Illumination intensity
If phosphorescent blue dopant is used, then short wavelength blue light is achieved, but difficulty in adjusting color coordinates occurs
Solution Approach 1:
The patent changes the optical parameters (refractive indices) of the inorganic oxide layers to achieve color coordinate adjustment. By controlling the refractive index relationships between layers A, B, and C, the device can achieve both short wavelength blue light and adjustable color coordinates.
Solution Approach 2:
The composite structure of inorganic oxide layers with organic emission layers provides both the short wavelength blue light emission and the ability to adjust color coordinates through optical cavity effects, resolving the limitation of using phosphorescent blue dopant alone.
3Loss of energy
If refractive index relationships are controlled between inorganic oxide layers, then quantum efficiency increases, but device manufacturing complexity increases
Solution Approach 1:
The patent optimizes specific parameters (refractive indices and thicknesses) of the inorganic oxide layers to enhance quantum efficiency. By carefully selecting materials with appropriate refractive indices and controlling layer thicknesses, high quantum efficiency is achieved while keeping the manufacturing process feasible.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device achieves increased quantum efficiency and improved light extraction through controlled refractive index relationships, leading to enhanced light-emitting performance and color stability.
Implementation Method 1
relationships between a refractive index a of the layer A, a refractive index b of the layer B, and a refractive index c of the layer C satisfy the following Equations (1) and (2): b−a=0.1 to 0.6 (1); and c−a=0.1 to 0.6 (2)
Data Source
AI summary
A light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an interlayer disposed between the first electrode and the second electrode and including an emission layer; wherein the interlayer further includes: a layer A including an oxide of an inorganic compound; a layer B adjacent to an upper portion of the layer A and including an oxide of an inorganic compound; and a layer C adjacent to a lower portion of the layer A and including an oxide of an inorganic compound, and relationships between a refractive index a of the layer A, a refractive index b of the layer B, and a refractive index c of the layer C satisfy the Equations (1) and (2) defined herein.