LED Charge Control Layer for Balanced Injection
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Solution Overview
Problem
Quantum-dot light emitting diodes (QLEDs) suffer from low luminous efficiency and short luminous lifetime due to charge imbalance and leakage, which affects the performance of OLED and QLED display devices.
Innovation Solution
Incorporating a charge control layer made of metal, such as post-transition metals or metal oxides, between the emitting material layer and the charge transfer layer to balance charge injection and prevent leakage, thereby enhancing luminous efficiency and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If current densities are increased or driving voltages are raised to improve luminance in OLED, then luminance is improved, but luminous lifetime becomes shorter due to thermal degradation and organic material deterioration
Solution Approach 1:
A charge control layer comprising a metal is introduced as an intermediary between the emitting material layer and the charge transfer layer. This charge control layer mediates charge injection and transport, enabling balanced charge injection without requiring excessive current densities or driving voltages, thereby improving luminance while extending luminous lifetime by reducing thermal degradation and organic material deterioration
Solution Approach 2:
The charge control layer changes the electrical parameters (charge injection balance, charge transport efficiency) of the device structure. By adjusting the metal composition and properties of the charge control layer, optimal charge balance is achieved, allowing operation at lower current densities and driving voltages that maintain high luminance while reducing thermal stress and extending device lifetime
2Loss of energy
If inorganic luminescence particles such as quantum dots are introduced to achieve high quantum yield and strong fluorescence, then luminous efficiency is improved, but charge injection balance deteriorates and charge leakage increases
Solution Approach 1:
The charge control layer acts as an intermediary between the inorganic quantum dot emitting material layer and the organic charge transfer layer. It facilitates balanced charge injection into the quantum dots while preventing charge leakage into adjacent layers, thereby maintaining high luminous efficiency with improved charge injection balance and reduced charge leakage
Solution Approach 2:
The device employs a composite structure combining inorganic quantum dots in the emitting material layer with an organic charge control layer comprising a metal. This composite material approach leverages the high quantum yield of inorganic particles while the organic charge control layer provides balanced charge injection, achieving both high luminous efficiency and reliable charge management
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 introduction of a metal charge control layer ensures balanced charge injection and reduced leakage, leading to improved luminous efficiency and extended luminous lifetime in QLEDs, as demonstrated by the fabrication and analysis of LEDs using Indium, Gallium, and Aluminum charge control layers.
Implementation Method 1
charges can be injected in balance and which minimize a charge leakage... the charge control layer comprises a metal... ensures balanced charge injection and reduced leakage
Implementation Method 2
an emitting material layer disposed between the first and second electrodes... QD or QR is an inorganic luminescence particle that emits light as unstable stated excitons shift from its conduction band to its valence band
Implementation Method 3
the charge control layer prevents holes leaking into or trapping at the charge transfer layer from the emitting material layer... minimize a charge leakage
Data Source
AI summary
The present disclosure relates to a light emitting diode (LED) that includes a charge control layer made of metal component and disposed between a first electrode and a second electrode and a light emitting device including the diode. Charges can be injected into an emitting material layer of the LED in a balanced manner, thus the luminous efficiency and a luminous lifetime of the LED and the light emitting device can be improved.