Tandem QLED P-N Layer Merging for Thickness Reduction

Solution Overview

Problem

Tandem-structured quantum-dot light-emitting diodes (QLEDs) require a carrier generation layer, increasing their thickness and turn-on voltage due to the need for a carrier generation layer between light-emitting layers.

Innovation Solution

A light-emitting element configuration with a P-type quantum-dot light-emitting layer and an N-type quantum-dot light-emitting layer adjacent to each other, functioning as a carrier generation layer, eliminates the need for a separate carrier generation layer, reducing thickness and turn-on voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a carrier generation layer is provided between light-emitting layers in a tandem-structured QLED, then external quantum efficiency is improved, but device thickness and turn-on voltage increase

Engineering Contradiction:

Improveexternal quantum efficiencyVSAvoiddevice thickness

Core Design Contradiction:

Loss of energyVSLength of stationary object

Solution Approach 1:

The patent merges the carrier generation layer function with the light-emitting layers by using P-type and N-type quantum-dot light-emitting layers that are adjacent to each other. The P-type layer generates holes and the N-type layer generates electrons, eliminating the need for a separate carrier generation layer and reducing device thickness while maintaining external quantum efficiency.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The P-type and N-type quantum-dot light-emitting layers serve multiple functions: they act as both light-emitting layers and carrier generation layers. The P-type layer generates holes for carrier injection, the N-type layer generates electrons, and both layers emit light, thereby reducing the overall device structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Loss of energy

If a carrier generation layer is provided between light-emitting layers in a tandem-structured QLED, then external quantum efficiency is improved, but turn-on voltage increases

Engineering Contradiction:

Improveexternal quantum efficiencyVSAvoidturn-on voltage

Core Design Contradiction:

Loss of energyVSPower

Solution Approach 1:

The patent merges the carrier generation layer function with the light-emitting layers by using P-type and N-type quantum-dot light-emitting layers that are adjacent to each other. The P-type layer generates holes and the N-type layer generates electrons, eliminating the need for a separate carrier generation layer and reducing device thickness while maintaining external quantum efficiency.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If a separate carrier generation layer is used, then carrier injection is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecarrier injectionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the carrier generation layer function with the light-emitting layers by using P-type and N-type quantum-dot light-emitting layers that are adjacent to each other. The P-type layer generates holes and the N-type layer generates electrons, eliminating the need for a separate carrier generation layer and reducing device thickness while maintaining external quantum efficiency.

Inventive Principle:

Principle #5Merging (Combining)

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

This configuration improves external quantum efficiency and reduces manufacturing complexity and yield, while enabling multiple photon emission from a single light-emitting element with fewer stacked layers.

Implementation Method 1

the at least one pair of light-emitting layers includes a P-type quantum-dot light-emitting layer, and an N-type quantum-dot light-emitting layer including a second quantum dot (50, 152)

Methodology Applied

Scientific EffectCharge separation:

Implementation Method 2

a light-emitting element that includes quantum dots in its light-emitting layer

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS20240081086A1Ligh-emitting element and light-emitting device

Publication Date: 2024.03.07 SHARP KK

AI summary

A light-emitting element according to the present disclosure includes at least one pair of light-emitting layers formed between a cathode and an anode and the at least one pair of light-emitting layers includes, in a stated order from the cathode, a P-type light-emitting layer and an N-type light-emitting layer adjacent to each other.