Stacked OLED Charge Generation Layers for Lower Driving Voltage
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Solution Overview
Problem
Current organic light-emitting devices face challenges in achieving high efficiency and long lifespan due to limitations in charge generation and transfer processes, leading to suboptimal luminescence efficiency and increased driving voltage.
Innovation Solution
The organic light-emitting device incorporates multiple light-emitting units with interposed charge generation layers, including n-type and p-type charge generation layers with specific doping layers composed of organic and inorganic materials, enhancing charge generation and transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional charge generation layers are used in organic light-emitting devices, then device structure is simple, but luminescence efficiency is low and driving voltage is high
Solution Approach 1:
The charge generation layer is divided into multiple distinct layers (first charge generation layer, second charge generation layer, third charge generation layer) with different material compositions and functions. Each layer is optimized for specific charge generation tasks, improving overall luminescence efficiency while maintaining manufacturability through systematic layering
Solution Approach 2:
The patent employs composite material structures in the charge generation layers, combining organic compounds (e.g., mCP, TCTA, BCP) with specific molecular structures and properties. These composite organic materials are designed to optimize charge generation, transport, and recombination processes, thereby enhancing luminescence efficiency
2Ease of manufacture
If conventional charge generation layers are used in organic light-emitting devices, then device structure is simple, but driving voltage is high
Solution Approach 1:
The charge generation system is segmented into multiple specialized layers, each with optimized material properties for specific voltage reduction functions. This segmentation allows for better charge balance and reduced energy barriers, lowering driving voltage while maintaining structural organization suitable for manufacturing
Solution Approach 2:
The patent optimizes molecular parameters of the organic compounds used in charge generation layers, including HOMO/LUMO energy levels, carrier mobility, and recombination rates. By carefully selecting and tuning these material parameters, the device achieves lower driving voltage requirements
3Loss of energy
If multiple light-emitting units are stacked with charge generation layers, then luminescence efficiency is improved, but device complexity increases
Solution Approach 1:
The device is segmented into multiple light-emitting units (first, second, third light-emitting units) with charge generation layers positioned between them. This segmentation enables independent optimization of each emitting unit while maintaining overall device functionality, improving luminescence efficiency through structured charge management
Solution Approach 2:
The charge generation layers are nested between the light-emitting units in a compact stacked configuration. This nested structure allows multiple functional layers to be integrated in a space-efficient manner, improving luminescence efficiency without proportionally increasing device volume or complexity
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 improves luminescence efficiency and reduces driving voltage by efficient charge generation and transfer, leading to a higher performance and longer lifespan of the organic light-emitting device.
Implementation Method 1
at least one of the m−1 p-type charge generation layers includes a first doping layer and a second doping layer... including a first organic material and a first inorganic material, the second doping layer includes a second organic material and a second inorganic material
Implementation Method 2
Carriers (such as the holes and electrons) may recombine in the emission layer to produce excitons. These excitons may transition from an excited state to the ground state to thereby generate light
Data Source
AI summary
An electronic apparatus includes an organic light-emitting device including: a first electrode, a second electrode facing the first electrode, m light-emitting units stacked between the first electrode and the second electrode and including at least one emission layer; and m−1 charge generating layers, each located between two neighboring light-emitting units of the m light-emitting units and including an n-type charge generating layer and a p-type charge generation layer, wherein m is an integer of 2 or more, at least one of the m−1 p-type charge generation layers includes a first doping layer and a second doping layer, the first doping layer includes a first organic material and a first inorganic material, the second doping layer includes a second organic material and a second inorganic material, and the first inorganic material and the second inorganic material are different from each other.