Thin-Film Light-Emitting Device Charge Generating Junction Layer

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Solution Overview

Problem

Existing thin-film light-emitting devices face challenges in achieving high power efficiency and current efficiency due to the complexity of forming a charge generating junction layer, particularly in large-area displays, where vacuum deposition processes are cumbersome and increase material costs, and the number of layers leads to higher driving voltage, reducing efficiency.

Innovation Solution

A thin-film light-emitting device with a charge generating junction layer composed of an annealed p-type semiconductor layer and an n-type semiconductor layer, formed using a solution process, which adjusts the concentration of oxygen vacancies at the interface between the p-type and n-type semiconductor layers, improving power and current efficiency, and is fabricated using oxide semiconductors to enhance resistance to oxygen and moisture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a charge generating junction layer is formed using vacuum deposition process, then the layer can be fabricated, but the process time is long (about 1 hour) and material costs increase

Engineering Contradiction:

Improvecharge generating junction layer fabricationVSAvoidprocess time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the vacuum deposition process with a solution process for fabricating the charge generating junction layer. This substitution eliminates the need for complex vacuum equipment and long processing times, reducing the fabrication time from about 1 hour to a much shorter duration while maintaining layer quality

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fabrication method from physical vapor deposition to chemical solution processing. This parameter change in the fabrication approach allows for faster processing and reduced material costs while achieving the same functional result of forming the charge generating junction layer

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the number of layers in light-emitting units is increased, then the device performance can be improved, but the driving voltage increases and efficiency decreases

Engineering Contradiction:

Improvedevice performanceVSAvoiddriving voltage

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent introduces a charge generating junction layer that modifies the electrical parameters at the interface between light-emitting units. This parameter change in the junction characteristics reduces the overall driving voltage required for multi-layer devices, thereby improving energy efficiency while maintaining enhanced device performance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If different materials are used to form each light-emitting unit, then the device performance can be optimized, but material costs increase

Engineering Contradiction:

Improvedevice performanceVSAvoidmaterial costs

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The charge generating junction layer serves multiple functions: it facilitates charge transfer between light-emitting units, reduces driving voltage, and can be fabricated using a universal solution process. This multi-functionality reduces the need for specialized expensive materials while maintaining optimized device performance

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enables a high-performance thin-film light-emitting device with improved power and current efficiency, reduced process time, and increased lifespan by stabilizing charge generation and injection, while also allowing for a low-cost tandem structure fabrication.

Implementation Method 1

a concentration of oxygen vacancies at an interface between the p-type and n-type semiconductor layers is adjusted by annealing the n-type semiconductor layer

Methodology Applied

Scientific EffectAnnealing: Annealing

Implementation Method 2

charge is generated at the interface between the p-type and n-type semiconductor layers, thereby stabilizing generation and injection of charge

Methodology Applied

Scientific EffectCharge generation at junction interface: Photovoltaic Effect

Data Source

PatentUS11638381B2Thin-film light-emitting device including charge generating junction layer and method of fabricating thin-film light-emitting device

Publication Date: 2023.04.25 UNIVERSITY INDUSTRY COOPERATION GROUP OF KYUNG HEE UNIVERSITY

AI summary

The present invention discloses a thin-film light-emitting device including a charge generating junction layer and a method of fabricating the thin-film light-emitting device. The thin-film light-emitting device including a charge generating junction layer according to one embodiment of the present invention includes a negative electrode; at least one light-emitting unit formed on the negative electrode and including a charge generating junction layer, an electron injection/transport layer, a thin-film light-emitting layer, and a hole injection/transport layer in a sequential order; and a negative electrode formed on the light-emitting unit. In the thin-film light-emitting device of the present invention, the charge generating junction layer has a layer-by-layer structure in which a p-type semiconductor layer and an n-type semiconductor layer are formed, and the concentration of oxygen vacancies at the interface between the p-type and n-type semiconductor layers is adjusted by annealing the n-type semiconductor layer.