Transparent OLED Pixel Electrode Design for Light Transmittance
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Solution Overview
Problem
Transparent organic light emitting displays face challenges with low light transmittance and image distortion due to the scattering of light through gaps in conductive patterns, which are close to visible light wavelengths, and lack of optical resonant effects in dual-emission types.
Innovation Solution
The design incorporates a substrate with pixels featuring separate emission and transmission areas, using transparent conductive layers and reflective layers made from specific metals and metal oxides, with the second emission area overlapping the transmission area to enhance light transmittance and prevent distortion by positioning conductive patterns on the emission areas rather than the transmission areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conductive patterns are placed in transmission areas to enable dual-emission functionality, then light emitting capability is improved, but light transmittance deteriorates due to scattering from conductive patterns
Solution Approach 1:
The pixel structure is segmented into distinct first emission areas with conductive patterns and second emission areas without conductive patterns. This segmentation allows different regions to serve different functions: the first emission areas provide light emission capability while the second emission areas maintain high light transmittance, thereby resolving the contradiction between light emitting capability and light scattering.
2Object-affected harmful factors
If transparent conductive layers are used in pixel electrodes, then light transmittance is improved, but electrical conductivity deteriorates compared to opaque conductors
Solution Approach 1:
The pixel electrode is constructed as a composite structure combining transparent conductive layers (such as ITO or IZO) with reflective layers (such as aluminum or silver). This composite material approach allows the electrode to simultaneously achieve sufficient electrical conductivity for device operation and high light transmittance for transparent display functionality, resolving the contradiction between these two properties.
3Productivity
If the display is designed as dual-emission type with emission areas on both sides, then light extracting efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The display structure implements local quality differentiation where the first emission areas contain complete dual-emission structures with conductive patterns and organic light emitting elements on both sides, while the second emission areas have simplified structures without conductive patterns. This localized approach allows the display to achieve high light extracting efficiency in emission regions while maintaining manufacturing feasibility through selective simplification in transmission regions.
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 improves light transmittance and prevents image distortion by minimizing the impact of conductive patterns on the transmission area, allowing for a dual-emission and transparent display with enhanced light extracting efficiency.
Implementation Method 1
a plurality of first pixel electrodes disposed on the first emission areas of the pixels, electrically connected to the pixel circuit units, and comprising transparent conductive layers and reflective layers
Implementation Method 2
organic layers disposed between the first pixel electrode and the first opposite electrode and between the second pixel electrode and the second opposite electrode, and comprising emission layers
Data Source
AI summary
An organic light emitting display is disclosed. In one embodiment, the display includes 1) a substrate, 2) a plurality of pixels formed on the substrate, wherein each of the pixels comprises at least one circuit region including i) a first light emission area, ii) a second light emission area iii) at least one transmission area transmitting external light, and iv) a pixel circuit unit and 3) a first pixel electrode formed in the first light emission area and electrically connected to the pixel circuit unit, wherein the first pixel electrode comprises a first transparent conductive layer and a reflective layer. The display may further include 1) a second pixel electrode formed in the second light emission area and electrically connected to the first pixel electrode, wherein the second pixel electrode comprises a second transparent conductive layer, 2) a first opposite electrode substantially directly below or above the first pixel electrode, 3) a second opposite electrode substantially directly below or above the second pixel electrode and 4) an organic emission layer formed between the first pixel electrode and the first opposite electrode and between the second pixel electrode and the second opposite electrode.