Polymer Hole Transport Layer for OLED Thermal Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current organic light emitting devices face challenges with materials that lack thermal stability, hinder efficient hole and electron transfer, and have inadequate chemical stability, charge mobility, and interface characteristics, limiting their efficiency and service life.
Innovation Solution
A polymer is developed, comprising specific units and end groups, which allows for adjustable electrical characteristics by including a first unit and a second unit with different electrical properties, thereby improving hole mobility and enhancing the performance and life characteristics of organic light emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If NPB is used as hole transport material, then the device can be manufactured, but the glass transition temperature is 100°C or less making it difficult to use in high electric current devices
Solution Approach 1:
The patent uses a composite material consisting of NPB as the base hole transport material combined with a specific guest molecule (compounds with formulas 1-1 to 1-20) that has high thermal stability. This guest-host system allows the material to achieve a glass transition temperature of 150°C or higher while maintaining the hole transport functionality of NPB, thus resolving the contradiction between manufacturability and thermal stability.
2Ease of manufacture
If PEDOT:PSS is used as hole transport material, then the device can be manufactured by solution application method, but the LUMO energy level is lower than the light emitting layer material causing poor interface characteristics and reduced efficiency
Solution Approach 1:
The patent changes the energy level parameters of the hole transport material by selecting guest molecules with appropriate HOMO and LUMO energy levels that are higher than those of the light emitting layer material. This parameter adjustment ensures proper energy level alignment at the interface, preventing electron leakage and improving device efficiency while maintaining solution processability.
3Device complexity
If a single type of unit is used in the polymer, then the structure is simple, but the electrical characteristics cannot be finely adjusted
Solution Approach 1:
The patent applies local quality by incorporating different types of units (first unit, second unit, and third unit) with distinct electrical properties into the polymer chain. Each unit type contributes different electrical characteristics, allowing fine adjustment of the overall polymer's electrical properties. The first unit provides hole transport capability, the second unit modifies electrical characteristics, and the third unit ensures solubility and processability, achieving both structural complexity and electrical versatility.
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 polymer effectively improves hole mobility and the overall performance and service life of organic light emitting devices, particularly when applied to hole transport layers, by finely adjusting electrical characteristics and ensuring stable interface properties.
Implementation Method 1
the material used in the organic light emitting device needs to have appropriate hole or electron mobility so as to make a balance between densities of holes and electrons in a light emitting layer
Data Source
Figure 1~2
AI summary
The present specification relates to a polymer comprising: a first unit represented by Chemical Formula 1; a second unit represented by Chemical Formula 1 and different from the first unit; a third unit represented by Chemical Formula 2; and an end group represented by Chemical Formula 3, and an organic light emitting device using the same.