OLED Electron Transport Layer Doping for Voltage Reduction
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Solution Overview
Problem
Conventional organic light emitting devices face challenges in reducing driving voltage and improving light emission efficiency while maintaining a long lifespan.
Innovation Solution
The organic light emitting device incorporates two or more light emitting units with a charge generation layer and electron transport layers doped with n-type dopants and metal salts or metal oxides, which facilitate efficient charge generation and transport, reducing driving voltage and enhancing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional single-layer electron transport layers are used, then device structure is simple, but driving voltage is high and light emission efficiency is low
Solution Approach 1:
The electron transport layer is divided into multiple sub-layers with different doping types (n-type, p-type, and undoped regions). This segmentation allows each sub-layer to perform specific functions: n-type regions facilitate electron injection, p-type regions facilitate hole blocking, and undoped regions provide electron transport. The segmented structure reduces overall driving voltage while improving electron transport efficiency compared to a conventional single-layer structure.
Solution Approach 2:
Different regions of the electron transport layer are assigned different doping characteristics tailored to local functional requirements. The n-type doped region near the electron injection interface has high electron mobility, the p-type doped region has high hole blocking capability, and the undoped region provides balanced transport. This local quality optimization resolves the contradiction by improving power efficiency without requiring a completely complex multi-layer structure.
2Device complexity
If conventional electron transport layers are used, then device structure is simple, but light emission efficiency is low
Solution Approach 1:
The electron transport layer is segmented into functional zones including n-type doped regions for efficient electron injection, p-type doped regions for hole blocking, and undoped regions for electron transport. This segmentation improves light emission efficiency by ensuring balanced charge carrier injection and transport, reducing non-radiative recombination, and improving exciton formation efficiency in the light emitting layer.
Solution Approach 2:
The doping concentration and doping type are varied across different regions of the electron transport layer. n-type regions have electron-donating dopants with specific concentration ranges, p-type regions have hole-donating dopants, and undoped regions have zero doping. These parameter changes optimize charge carrier densities and mobilities in different zones, significantly improving light emission efficiency without requiring excessive structural complexity.
3Productivity
If higher driving voltage is applied to improve light emission efficiency, then light emission efficiency improves, but device lifespan decreases
Solution Approach 1:
By optimizing the doping concentration parameters in the electron transport layer, the device achieves efficient charge carrier transport at lower driving voltages. The n-type doped regions provide high electron mobility, the p-type doped regions provide effective hole blocking, and the undoped regions provide balanced transport. This parameter optimization allows the device to maintain high light emission efficiency while operating at reduced voltages, thereby extending device lifespan by reducing electrical stress and heat generation.
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 significantly reduces driving voltage, improves light emission efficiency, and extends the device's lifespan compared to conventional devices.
Implementation Method 1
an electron transport layer is provided between the charge generation layer and the light emitting unit placed closer to the first electrode of the two adjacent light emitting units, and the electron transport layer includes a first electron transport layer doped with an n-type dopant, and a second electron transport layer doped with a metal salt, metal oxide or organic metal salt
Implementation Method 2
the electron transport layer includes a first electron transport layer doped with an n-type dopant, and a second electron transport layer doped with a metal salt, metal oxide or organic metal salt
Data Source
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AI summary
The present disclosure provides an organic light emitting device that includes a first electrode, a second electrode, and two or more light emitting units provided between the first electrode and the second electrode, wherein a charge generation layer is provided between, among the light emitting units, two light emitting units that are adjacent to each other, an electron transport layer is provided between the charge generation layer and the light emitting unit placed closer to the first electrode of the two adjacent light emitting units, and the electron transport layer includes a first electron transport layer doped with an n-type dopant, and a second electron transport layer doped with a metal salt, metal oxide or organic metal salt.