OLED Host-Dopant Deposition via Joule Heating Segmentation
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Solution Overview
Problem
Existing methods for depositing organic materials in OLEDs face issues with uneven mixing of hosts and dopants, leading to low luminance characteristics due to partial uneven mixing during the deposition process.
Innovation Solution
A method utilizing two donor substrates for planar deposition by joule heating, where hosts and dopants are premixed, separated into layers based on vaporization temperature, and then uniformly mixed on a target substrate, ensuring even deposition and increased luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hosts and dopants are mixed in a liquid state for deposition, then the deposition process is simple, but the mixing uniformity is poor leading to low luminance characteristics
Solution Approach 1:
The patent divides the deposition process into two separate stages using two different donor substrates: first depositing the host material, then depositing the dopant material. This segmentation allows each material to be deposited under optimized conditions, ensuring uniform distribution and improving mixing uniformity while maintaining process simplicity.
Solution Approach 2:
The patent performs preliminary separation of hosts and dopants into different layers on the first donor substrate before deposition. By pre-organizing the materials in distinct layers, the subsequent deposition process automatically achieves uniform mixing without requiring complex liquid-state mixing procedures.
2Device complexity
If a single donor substrate is used for deposition, then the device structure is simple, but the mixing uniformity of hosts and dopants is poor
Solution Approach 1:
The patent uses two separate donor substrates to segment the deposition process, with each substrate dedicated to depositing a specific material (host or dopant). This segmentation of the donor substrate system enables precise control over material distribution and achieves uniform mixing without requiring complex single-substrate structures.
Solution Approach 2:
The first donor substrate acts as an intermediary that temporarily holds separated layers of host and dopant materials before final deposition onto the target substrate. This intermediary structure facilitates uniform material transfer and ensures consistent mixing ratios.
3Productivity
If hosts and dopants are deposited simultaneously, then the deposition process is fast, but the mixing uniformity is poor due to uneven vaporization
Solution Approach 1:
The patent segments the deposition of hosts and dopants into sequential steps using two different donor substrates. This segmentation allows each material to vaporize and deposit at its optimal rate, ensuring uniform distribution while maintaining overall deposition efficiency.
Solution Approach 2:
The patent changes the deposition parameters by using separate donor substrates with different thermal properties optimized for each material. This allows independent control of vaporization temperatures and deposition rates for hosts and dopants, achieving uniform mixing without sacrificing productivity.
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 approach significantly enhances luminous efficiency and enables the production of large-area organic light-emitting devices like OLED lighting with improved luminance characteristics.
Implementation Method 1
heating the premix by applying an electric field to the first donor substrate
Implementation Method 2
heating the host and the dopant by applying an electric field to the second donor substrate
Implementation Method 3
depositing the host and the dopant that are uniformly mixed on a target substrate
Data Source
AI summary
The present invention relates to method for depositing an organic material for an organic light emitting device and an organic light emitting device manufactured thereby. The method includes the steps of: applying a premix in which a host and a dopant are premixed, to a first donor substrate; heating the premix by applying an electric field to the first donor substrate; depositing the host and the dopant separated into different layers on a second donor substrate, with the host or the dopant having a relatively low vaporization temperature first deposited from the premix onto the second donor substrate and then the dopant or the host having a relatively high vaporization temperature deposited later onto the second donor substrate; heating the host and the dopant by applying an electric field to the second donor substrate; and depositing the host and the dopant that are uniformly mixed on a target substrate.