Organic Light-Emitting Layer Molecular Orientation for Efficiency
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Solution Overview
Problem
Existing organic electroluminescence devices face challenges in enhancing device performance, particularly in achieving high light emission efficiency and preventing deactivation due to the overlap of emission and absorption spectra between the hole transport and organic light-emitting layers.
Innovation Solution
The organic electroluminescence device is configured with a hole transport layer, an organic light-emitting layer made of material with a specific molecular orientation degree (0.66<S′<0.75), and an electron transport layer, where the light emission region is positioned on the electron transport layer side, reducing deactivation and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the hole transport layer and organic light-emitting layer are configured with overlapping emission and absorption spectra, then the device structure is simplified and manufacturing is easier, but deactivation occurs and light emission efficiency decreases
Solution Approach 1:
The patent applies parameter changes by controlling the molecular orientation degree of the organic light-emitting material within a specific range (0.66<S′<0.75) and positioning the light emission region at a specific location within the organic light-emitting layer. This parameter optimization reduces the overlap between emission and absorption spectra, thereby minimizing deactivation while maintaining the coated film structure for ease of manufacture.
2Loss of energy
If the molecular orientation degree of the organic light-emitting material is increased to reduce deactivation, then light emission efficiency improves, but the selection of suitable materials becomes more restricted
Solution Approach 1:
The patent defines a specific parameter range for molecular orientation degree (0.66<S′<0.75) that balances light emission efficiency and material selection flexibility. This parameter optimization allows sufficient freedom in material selection while ensuring the light emission region is properly positioned to minimize deactivation.
3Loss of energy
If the light emission region is positioned on the electron transport layer side to reduce deactivation, then light emission efficiency improves, but the device structure becomes more complex
Solution Approach 1:
The patent positions the light emission region within the organic light-emitting layer at a specific location closer to the electron transport layer side. This positional parameter optimization reduces deactivation from the hole transport layer while maintaining the standard five-layer device structure, thus improving efficiency without significantly increasing structural 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 enhances light emission efficiency by minimizing deactivation from the hole transport layer and allows for easier selection of materials with wider energy gaps, thereby improving device performance even in coated organic electroluminescence devices.
Implementation Method 1
an organic light-emitting layer configured by a coated film, the organic light-emitting layer being made of an organic light-emitting material
Data Source
AI summary
An organic electroluminescence device includes, in order, a first electrode, a hole transport layer, an organic light-emitting layer, an electron transport layer, and a second electrode. The hole transport layer is configured by a coated film. The organic light-emitting layer is configured by a coated film. The organic light-emitting layer is made of an organic light-emitting material that has a molecular orientation degree specified by a parameter S′. The parameter S′ satisfies an inequality: 0.66<S′<0.75, provided that S′={(2×ko)/(ke+2ko)}. In this expression, ko denotes an extinction coefficient in a film-plane direction of the organic light-emitting layer, and ke denotes an extinction coefficient in a film-thickness direction of the organic light-emitting layer.