Pixel Electrode Layout With Sub-Common Electrode for Higher Luminance
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Solution Overview
Problem
Existing display devices face challenges in improving light emission efficiency of pixels.
Innovation Solution
The display device incorporates a pixel structure with a sub-common electrode covering the top surface and a portion of the side surface of the light emitting stack structure, along with an insulating film covering the outer circumferential surface, and a voltage configuration where the sub-common electrode's voltage level is between the common electrode and pixel electrode levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional electrode structure is used, then the device complexity is low, but the light emission efficiency is insufficient
Solution Approach 1:
The common electrode is divided into two separate electrodes: a common electrode and a sub-common electrode. This segmentation allows independent optimization of their functions - the common electrode provides the main common potential while the sub-common electrode specifically addresses the light emission efficiency issue by covering the light emitting stack structure, thereby resolving the contradiction between improved productivity and increased device complexity
Solution Approach 2:
The sub-common electrode is positioned to cover specifically the light emitting stack structure (including the top surface and side surfaces of the light emitting element), providing localized electrical field optimization where it is most needed for light emission, rather than uniformly across the entire device, thus improving light emission efficiency without unnecessarily increasing overall complexity
2Productivity
If the sub-common electrode covers the side surface of the light emitting stack structure, then the light emission efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The sub-common electrode extends in multiple dimensions - covering not only the top surface but also the side surfaces of the light emitting stack structure. This three-dimensional coverage approach ensures comprehensive electrical field optimization from multiple angles, improving light emission efficiency while the extended coverage area provides manufacturing tolerance to positioning variations
3Reliability
If the insulating film covers the outer circumferential surface, then the electrical insulation is improved, but the device complexity increases
Solution Approach 1:
The insulating film serves multiple functions simultaneously: it provides electrical insulation between the sub-common electrode and surrounding conductive elements, protects the light emitting stack structure, and maintains the structural integrity of the device. This multi-functionality justifies the added layer while delivering reliable electrical insulation without proportionally increasing complexity
Data Source
AI summary
A display device includes a pixel circuit layer including a sub-pixel circuit having at least one transistor, an electrode layer disposed on the pixel circuit layer and including a pixel electrode electrically connected to the sub-pixel circuit and a common electrode spaced apart from the pixel electrode, a light emitting stack structure disposed on the electrode layer and including a first semiconductor layer, a second semiconductor layer disposed on the first semiconductor layer, and an active layer interposed between the first and second semiconductor layers, a first bonding electrode connected to the first semiconductor layer and electrically connected to the pixel electrode, a second bonding electrode connected to a portion of the second semiconductor layer not overlapping the first semiconductor layer and the active layer and electrically connected to the common electrode, and a sub-common electrode covering at least a top surface of the light emitting stack structure.