Organic EL Light Emitting Layer Ionization Potential Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current organic electroluminescent devices face challenges in achieving high light emission efficiency and driving durability while operating at low driving voltage, particularly due to the requirement of high voltage for brightness and the resulting power consumption and durability issues.
Innovation Solution
The device incorporates a light emitting layer with specific ionization potential and electron affinity ranges for its main constituent materials, along with intermediate layers, and includes a compound with a lower ionization potential within the light emitting layer to control hole and electron mobility, ensuring efficient light emission and low driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high voltage is applied to achieve high brightness, then light emission efficiency is improved, but electrical power consumption increases and driving durability deteriorates
Solution Approach 1:
The patent modifies the energy level parameters of the light emitting layer by selecting materials with specific ionization potentials (5.8-6.2 eV) and electron affinities (2.0-2.8 eV), and by controlling hole mobility (10^-6 to 10^-4 cm²/Vs) and electron mobility (10^-5 to 10^-3 cm²/Vs) within defined ratios, enabling efficient light emission at reduced operating voltages
Solution Approach 2:
The patent employs composite material design by combining a host material with a dopant material in the light emitting layer, where the host provides the base structure and the dopant (0.1-20 wt%) enhances charge carrier generation and transport properties, achieving high brightness efficiency at low voltage
2Illumination intensity
If high voltage is applied to achieve high brightness, then light emission efficiency is improved, but driving durability deteriorates
Solution Approach 1:
The patent establishes specific parameter ranges for the light emitting layer materials (ionization potential 5.8-6.2 eV, electron affinity 2.0-2.8 eV, hole mobility 10^-6 to 10^-4 cm²/Vs, electron mobility 10^-5 to 10^-3 cm²/Vs) that enable high brightness operation while maintaining stable device performance and extended driving durability through optimized charge carrier dynamics
3Illumination intensity
If compound with lower ionization potential is incorporated to control hole mobility, then light emission efficiency is improved, but device complexity increases
Solution Approach 1:
The patent incorporates a dopant material with lower ionization potential than the host material to modulate hole mobility within the target range (10^-6 to 10^-4 cm²/Vs), optimizing light emission efficiency while maintaining a relatively simple single-layer light emitting structure without additional complex components
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 enables high light emission efficiency and satisfactory driving durability at low driving voltage, enhancing the performance and longevity of the organic electroluminescent device.
Implementation Method 1
organic electroluminescent devices using a thin film material that is excited by passing an electric current therethrough and emits light
Data Source
Figure 1
AI summary
An organic electroluminescent device comprising: a positive electrode and a negative electrode; a light emitting layer interposed between the electrodes; at least one positive electrode-side intermediate layer interposed between the positive electrode and the light emitting layer; and at least one negative electrode-side intermediate layer interposed between the negative electrode and the light emitting layer, wherein expressions (1) Ip(EML) - 0.1 eV < Ip(li) < Ip(EML) + 0.1 eV and (2) Ea(EML) - 0.1 eV < Ea(2i) < Ea(EML) + 0.1 eV are satisfied; expression (3) 0.1 ≤ µh/µe ≤ 10 is satisfied; and the light emitting layer contains a compound having an ionization potential lower than the ionization potential Ip(EML) of the main constituent material of the light emitting layer in an amount of from 0.5% by mass to 20% by mass relative to the total mass of the light emitting layer.