Hybrid OLED with Quantum Dots for Exciton Yield
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Solution Overview
Problem
Organic light emitting devices (OLEDs) face inefficiencies in light emission due to the low ratio of singlet excitons participating in light emission, as they are quantum-statistically outnumbered by triplet excitons, limiting the maximum yield of singlet excitons to about 25% of total excitons.
Innovation Solution
Incorporating second light emitting members with compound semiconductors and light emitting impurities, such as quantum dots, in a mixed configuration with first light emitting members, to increase the generation rate of singlet and triplet excitons by supplying energy and altering the internal conversion rates, thereby enhancing the efficiency of light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only first light emitting members are used in the OLED, then the device structure is simple, but the internal quantum efficiency is limited to about 25% due to the low ratio of singlet excitons
Solution Approach 1:
The patent combines first light emitting members (organic materials) and second light emitting members (compound semiconductors with quantum dots) into a hybrid structure. The second light emitting members are disposed between neighboring first light emitting members and contact them, creating a mixed configuration that leverages the advantages of both material systems to improve exciton generation and light emission efficiency.
Solution Approach 2:
The patent employs composite light emitting members consisting of organic compounds and compound semiconductors with quantum dots. The second light emitting members include compound semiconductors such as InN, GaAs, GaInAs, InP, GaSb, and quantum dots like CdSe, CdTe, ZnS, CdS, PdS, PbSe, and CdHgTe, forming a composite structure that enhances the generation rate of singlet and triplet excitons.
2Loss of energy
If second light emitting members with compound semiconductors and quantum dots are added to improve light emission efficiency, then the internal quantum efficiency increases, but the device complexity increases
Solution Approach 1:
The patent implements local quality by strategically positioning second light emitting members between neighboring first light emitting members rather than uniformly distributing all components throughout the device. This localized arrangement allows the complex hybrid structure to be concentrated in specific regions where it most effectively enhances exciton generation, while maintaining simpler structures in other areas.
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 increases the yield of singlet and triplet excitons, improving the internal quantum efficiency of OLEDs by altering the energy levels and intersystem crossing rates, leading to enhanced light emission efficiency.
Implementation Method 1
One of the two electrodes injects holes and the other of the two electrodes injects electrons into the light emitting layer. The injected electrons and holes are combined to form excitons, and the excitons release energy in the form of emitted light.
Implementation Method 2
second light emitting members being in contact with the first light emitting members and emitting light having a wavelength. The wavelength is in a range of about 600 nm to about 2500 nm
Implementation Method 3
The quantum dot may include at least one of CdSe, CdTe, ZnS, CdS, PdS, PbSe, and CdHgTe
Data Source
AI summary
An organic light emitting diode (OLED) display including a first electrode formed on a substrate, a second electrode facing the first electrode, first light emitting members disposed between the first electrode and the second electrode and emitting light included in a visible spectrum, and second light emitting members being in contact with the first light emitting members and emitting light having a wavelength. The wavelength is in a range of about 600 nm to about 2500 nm.