Flexible Substrate Doping with TiO2 Nanoparticles for Light Extraction
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Solution Overview
Problem
Flexible OLEDs suffer from low light extraction efficiency due to a higher proportion of light being trapped in waveguide and plasma modes, resulting in a lower proportion of light being externally emitted.
Innovation Solution
Incorporating titanium dioxide nano-particles with diameters between 200 to 400 nanometers into the flexible substrate and organic photoresist layer to refract light emitted from the organic light-emitting layer, enhancing light scattering and extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light emitting from double-sides is used in flexible OLEDs, then the viewing angle and brightness are improved, but the light extraction rate decreases due to higher proportion of waveguide mode and plasma mode
Solution Approach 1:
The patent changes the optical parameters of the flexible substrate by doping it with titanium dioxide nano-particles (200-400 nm in diameter). This modification alters the refractive index and optical properties of the substrate, enabling effective refraction of light from waveguide and plasma modes into the external mode, thereby improving light extraction rate while maintaining the double-sided emission structure
Solution Approach 2:
The titanium dioxide nano-particles act as an intermediary medium between the organic light emitting layer and the external environment. These nano-particles facilitate the conversion of trapped light modes (waveguide and plasma) into externally extractable light through refraction, solving the contradiction between maintaining double-sided emission and improving light extraction efficiency
2Loss of energy
If nano-particles are added to increase light extraction efficiency, then the light extraction rate improves, but the device complexity increases
Solution Approach 1:
The patent merges the optical enhancement function into the existing flexible substrate by doping it with titanium dioxide nano-particles. Rather than adding a separate complex optical extraction layer, the nano-particles are integrated directly into the substrate material, simplifying the overall device structure while achieving improved light extraction efficiency
Solution Approach 2:
The use of nano-particles creates a porous or heterogeneous structure within the flexible substrate at the nanoscale. This porous-like distribution of titanium dioxide particles provides numerous refraction interfaces for light extraction without significantly increasing the macroscopic device complexity or thickness
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 addition of nano-particles increases light extraction efficiency from 40% to 60%, improving the external light emission and overall performance of flexible OLEDs.
Implementation Method 1
the flexible substrate is doped with a plurality of nano-particles that are configured to refract the light emitted from the organic light-emitting layer to an external environment
Data Source
AI summary
A flexible display apparatus is provided in the present disclosure and includes a flexible substrate, an organic electroluminescent device, and a plurality of thin film transistors disposed between the flexible substrate and the organic electroluminescent device. The organic electroluminescent device is controlled by the thin film transistors to emit light. The flexible substrate is doped with a plurality of nano-particles that are configured to refract the light emitted from the organic light-emitting layer to an external environment.