Organic Light Emitting Device Low Refractive Conductive Layer
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Solution Overview
Problem
The outcoupling efficiency of organic light emitting devices is limited, typically ranging from 15 to 20%, which restricts their quantum and power efficiency, affecting power consumption and lifetime.
Innovation Solution
An organic light emitting device is designed with a substrate, a uniformly patterned first electrode layer, a low refractive conductive layer with a lower refractive index than the organic layer, and a second electrode layer, featuring a taper angle between 15 to 90 degrees and a microlens array on the substrate, enhancing light emission directionality and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light is emitted in random directions with homogeneous angular distribution, then the device structure is simple, but the outcoupling efficiency is limited to 15-20%
Solution Approach 1:
The first electrode layer is segmented into a periodic pattern structure rather than being continuous. This segmentation creates multiple interfaces that scatter light and break waveguide modes, increasing the probability of photons escaping the organic layer. The periodic pattern with intervals greater than the light wavelength effectively segments the electrode function while maintaining electrical conductivity through the transparent material.
Solution Approach 2:
A low refractive index conductive material is applied locally at the interface between the first electrode layer and the organic layer. This localized modification of refractive index creates optimal optical conditions at the critical interface for light extraction, while other layers maintain their original properties. The low refractive index material specifically addresses the optical mismatch at this interface without requiring changes to the entire device structure.
2Loss of energy
If the first electrode layer is uniformly patterned with periodic intervals greater than light wavelength, then the outcoupling efficiency increases, but the device complexity increases
Solution Approach 1:
The periodic interval of the first electrode layer pattern is specifically designed to be greater than the wavelength of emitted light. This parameter change is critical because it allows the patterned structure to effectively scatter visible light wavelengths while maintaining electrical conductivity. By tuning this geometric parameter, the design achieves enhanced light extraction without requiring complex nanoscale patterning that would increase manufacturing difficulty.
3Loss of energy
If a low refractive index conductive material is used at the interface, then the outcoupling efficiency increases, but the manufacturing complexity increases
Solution Approach 1:
The low refractive index conductive material serves multiple functions simultaneously: it provides electrical conductivity for charge injection, creates optimal refractive index matching at the interface for light extraction, and can be deposited using standard thin-film techniques. This multi-functionality reduces the need for additional specialized components or complex manufacturing steps, as one material layer accomplishes what would otherwise require multiple separate components.
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 solution significantly increases the outcoupling efficiency, external quantum efficiency, and power efficiency of the organic light emitting device, reducing wavelength dependence and inactive electrical areas, thereby extending the device's lifetime and maintaining high brightness.
Implementation Method 1
a low refractive conductive layer disposed on the first electrode layer, and including a conductive material with a lower refractive index than a refractive index of an organic layer
Implementation Method 2
a microlens array on the substrate, enhancing light emission directionality and efficiency
Implementation Method 3
a taper angle between an end of a pattern of the first electrode layer and a surface of the substrate may be in the range of about 15 to about 90 degrees
Data Source
AI summary
An organic light emitting device having increased outcoupling efficiency, a lighting apparatus including the organic light emitting device, and an organic light emitting display apparatus including the organic light emitting device. The organic light emitting device includes a substrate, a first electrode layer that is uniformly patterned on the substrate, a low refractive conductive layer disposed on the first electrode layer, and having a conductive material with a lower refractive index than a refractive index of an organic layer that is disposed on the low refractive conductive layer, and a second electrode layer formed on the organic layer.