Transparent OLED Pixel Electrode Design for High Transmittivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Transparent organic light emitting display devices face challenges with low transmittivity and outcoupling efficiency due to the presence of patterns like TFTs and wirings, leading to image distortion and difficulty in manufacturing.
Innovation Solution
The design includes a substrate with a transmission area and pixel areas, featuring first pixel electrodes with a reflection layer and a second pixel electrode made of light-transmissible conductive material, an organic layer, and an opposite electrode, optimized to increase transmittivity and outcoupling efficiency by reducing light diffusion and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transparent TFT and transparent conductive materials are used to achieve transparency, then the device transparency is improved, but the transmittivity is reduced due to the presence of patterns and small spaces between components
Solution Approach 1:
A filling layer is introduced as an intermediary component to fill the spaces between patterns (TFTs and wirings). This filling layer has a refractive index higher than the surrounding medium, which reduces light diffusion and improves transmittivity without compromising the transparency achieved through transparent TFT and conductive materials. The filling layer acts as a mediator that optically connects the patterns to the surrounding medium, reducing the harmful optical effects of the spaces between components.
2Illumination intensity
If transparent anode is used to maintain high transmittivity, then the transmittivity is improved, but the outcoupling efficiency is reduced due to inability to use reflective anode and optical resonance effects
Solution Approach 1:
The patent applies different optical properties to different regions of the pixel electrode. The pixel electrode includes a reflective layer in certain areas to enhance outcoupling efficiency through optical resonance effects, while maintaining transparent conductive material in other areas to preserve transmittivity. This local differentiation of optical properties allows the device to simultaneously achieve high transmittivity and high outcoupling efficiency by optimizing each region for its specific function.
3Adaptability or versatility
If patterns (TFTs and wirings) are present in the transmission area, then the device functionality is improved, but light diffusion occurs causing image distortion
Solution Approach 1:
The filling layer serves as an optical intermediary that reduces the refractive index mismatch between the patterns (TFTs and wirings) and the surrounding medium. By filling the spaces with material having an appropriate refractive index, light diffusion is minimized, thereby reducing image distortion while preserving the necessary patterns for device functionality.
Solution Approach 2:
The patent changes the refractive index parameter of the filling material to optimize optical performance. By selecting a filling layer with a refractive index higher than the surrounding medium, the patent reduces light diffusion and improves image quality. This parameter optimization allows the patterns to maintain their functional necessity while minimizing their harmful optical effects.
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 transmittivity and outcoupling efficiency, providing a clearer and brighter image with reduced distortion, while maintaining the display's transparency and functionality.
Implementation Method 1
a first pixel electrode formed on the passivation layer and respectively electrically connected to the plurality of TFTs, the electrodes being overlapped with the plurality of TFTs so as to cover the plurality of TFTs and including a reflection layer formed of a light-reflecting conductive material
Implementation Method 2
an organic layer interposed between the plurality of first and second pixel electrodes and the opposite electrode and including an emission layer
Data Source
AI summary
An organic light emitting display device comprises: a substrate; a plurality of thin film transistors (TFTs) formed on a first surface of the substrate; a passivation layer covering the plurality of TFTs; a plurality of first pixel electrodes formed on the passivation layer and respectively electrically connected to the plurality of TFTs, and overlapping with the plurality of TFTs so as to cover the plurality of TFTs, and including a reflection layer formed of a light-reflecting conductive material; a second pixel electrode formed of a light-transmitting conductive material and disposed on the passivation layer so as to be electrically connected to the plurality of first pixel electrodes; an opposite electrode formed such that light is transmitted or reflected therethrough, and disposed opposite the plurality of first pixel electrodes and the second pixel electrode; and an organic layer interposed between the plurality of first pixel electrodes and the second pixel electrode, and including an emission layer. Accordingly, transmittivity of the organic light emitting display device is increased, and optical outcoupling efficiency of the organic light emitting display device is also increased during double-sided emission.