OLED Display Substrate Layer Structure for Interface Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing OLED display technologies face challenges with interface degradation and material defects, particularly at the electron block layer, leading to short service life and color drift issues due to excessive electron accumulation and material bond distortions.
Innovation Solution
The implementation of a display substrate with a hole block layer and electron transport layer having specific electromigration rates and energy level differences, along with a light modulation layer with controlled refractive indices, to manage electron and hole migration, thereby stabilizing the electron block layer and improving device longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OLED structures are used, then device simplicity is maintained, but interface degradation and material defects occur leading to short service life
Solution Approach 1:
The patent divides the electron block layer into two separate functional layers: a hole block layer (HBL) and an electron transport layer (ETL). This segmentation allows each layer to be optimized independently for its specific function, preventing interface degradation that occurs in conventional single-layer structures and thereby extending device service life.
Solution Approach 2:
The hole block layer serves as an intermediary layer between the emitting layer and the electron transport layer. It mediates the interaction between holes and electrons, preventing excessive electron accumulation at interfaces while maintaining proper charge balance, thus reducing material bond distortions and improving reliability.
2Illumination intensity
If electron injection density is increased to improve luminance efficiency, then brightness is enhanced, but excessive electron accumulation causes interface degradation and color drift
Solution Approach 1:
The patent optimizes the electromigration rates of electrons and holes in the HBL and ETL layers, establishing specific relationships between these parameters (EETL/EHBL>1, |HOMOETL-HOMOHBL|≥0.1 eV, |LUMOETL-LUMOHBL|≥0.2 eV). These parameter changes enable controlled electron injection density that maintains high luminance efficiency while preventing excessive electron accumulation that causes color drift.
Solution Approach 2:
Different regions of the light emitting structure are given different material properties. The HBL has specific HOMO and LUMO energy levels optimized for hole blocking, while the ETL has different energy levels optimized for electron transport. This local quality differentiation allows precise control of charge distribution to maintain color stability at high luminance.
3Ease of manufacture
If traditional material structures are used, then manufacturing simplicity is maintained, but material bond distortions occur leading to performance degradation
Solution Approach 1:
The patent employs composite material structures where the HBL and ETL are formed from specific organic compounds with tailored molecular structures (containing aryl and heteroaryl groups). These composite material designs prevent material bond distortions by ensuring proper energy level alignment and molecular packing, thereby improving material stability while remaining compatible with existing OLED manufacturing processes.
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 enhances the stability and service life of OLED devices by controlling electron injection density and recombination regions, reducing material deterioration, and improving luminance efficiency.
Implementation Method 1
the hole block layer and the electron transport layer satisfy: EETL/EHBL>1; where EETL is the electromigration rate of the electron transport layer, and EHBL is the electromigration rate of the hole block layer
Implementation Method 2
The light emitting principle of the OLED is that holes and electrons are injected into the emitting layer from the anode and the cathode respectively, when the electrons and the holes meet in the emitting layer, the electrons and the holes are recombined to produce excitons, and when transitioning from an excited state to a ground state, these excitons emit light
Implementation Method 3
the light modulation layer has a refractive index nR in a wavelength range of 600 nm to 640 nm, a refractive index nG in a wavelength range of 510 nm to 550 nm, and a refractive index nB in a wavelength range of 440 nm to 480 nm
Data Source
AI summary
Provided are a display substrate and a display apparatus. The display substrate includes a drive circuit layer and a light emitting structure layer stacked on a substrate. The light emitting structure layer includes an anode, a cathode, and an emitting layer, a hole block layer, and an electron transport layer disposed between the anode and the cathode; the hole block layer and the electron transport layer satisfy: EETL/EHBL>1; where EETL is the electromigration rate of the electron transport layer, and EHBL is the electromigration rate of the hole block layer.