OLED Exciton Blocking Layer Design for Luminous Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In organic light-emitting diode (OLED) array substrates, the lack of an exciton blocking layer results in low luminous efficiency due to the quenching of triplet state excitons, and adding such a layer complicates the fabrication process and increases costs, as it requires additional vapor deposition devices.
Innovation Solution
Incorporating an exciton blocking layer made of a host material with the highest highest occupied molecular orbital (HOMO) and triplet state energy level among the light-emitting layers, which also serves as a hole blocking layer for other colors, improving quenching of triplet state excitons and luminous efficiency without the need for additional fabrication devices or costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an exciton blocking layer is added to improve luminous efficiency by increasing triplet state exciton quenching, then luminous efficiency is improved, but the fabrication device complexity and cost increase due to requiring additional vapor deposition devices
Solution Approach 1:
The patent applies the universality principle by designing the exciton blocking layer to serve multiple functions simultaneously: it blocks excitons to improve triplet state quenching while also acting as a hole blocking layer for other color light-emitting layers. This multi-functionality eliminates the need for separate dedicated exciton blocking layers for each color, thereby improving luminous efficiency without proportionally increasing fabrication device complexity
Solution Approach 2:
The patent merges the exciton blocking function with the hole blocking function into a single layer structure. By combining these two functions that were previously required to be implemented by separate layers, the patent reduces the total number of layers needed while achieving both exciton quenching improvement and hole blocking, thus improving luminous efficiency without linearly increasing fabrication complexity
2Loss of energy
If an exciton blocking layer is added to improve triplet state exciton quenching, then luminous efficiency is improved, but the number of layers and fabrication steps increase
Solution Approach 1:
The exciton blocking layer is designed with universal functionality to serve multiple purposes: exciton blocking for triplet state quenching and hole blocking for carrier management. This multi-functionality reduces the total number of separate layers needed, thereby improving fabrication process efficiency while still achieving the luminous efficiency improvement through triplet state quenching
Solution Approach 2:
The patent utilizes parameter changes in the energy levels of the host material (specifically HOMO energy level and triplet state energy level) to achieve multiple functions in a single layer. By selecting materials with appropriate energy level parameters, the exciton blocking layer can simultaneously block excitons and holes, improving luminous efficiency without adding excessive fabrication steps
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 implementation of the exciton blocking layer enhances luminous efficiency by increasing the quenching of triplet state excitons and balances carrier transport, improving the overall performance of OLEDs without adding complexity or cost to the fabrication process.
Implementation Method 1
when an electron and a hole are transported to the light-emitting layer, an exciton (an excited state molecule) is generated in the guest material. When the exciton falls back to a ground state, energy is released in a form of light, that is, light is emitted
Implementation Method 2
a HOMO energy level and a triplet state energy level of the layer cannot be less than the HOMO energy level and the triplet state energy level of the host material of the light-emitting layer; in this way, the triplet state excitons are limited in the light-emitting layer, the possibility of quenching among the triplet state excitons is increased, and the luminous efficiency is improved
Data Source
AI summary
An organic light-emitting diode (OLED) array substrate and a display apparatus are provided. The OLED array substrate includes a plurality of OLEDs; the OLED includes an anode, a light-emitting layer and a cathode which are provided sequentially; the light-emitting layers are divided into a plurality of types by color (that is, the light-emitting layers are configured for emitting light of a plurality of colors), and are made of a host material and a guest material doped in the host material; and the OLED further includes an exciton blocking layer provided between the cathode and the light-emitting layer and in contact with the light-emitting layer, which is made of a host material of one light-emitting layer, and the host material of the one light-emitting layer has the biggest highest occupied molecular orbital energy level and the biggest triplet state energy level in the host materials of all light-emitting layers.