OLED Cathode Contact via Insulating Layer Stair Gap
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Solution Overview
Problem
In OLED displays, the contact between the cathode and power wiring in non-display areas can lead to defects due to film separation, necessitating effective prevention of cathode contact portion separation.
Innovation Solution
The OLED display design includes a thin film transistor on a display substrate with insulating layers forming contact holes to expose power wirings, allowing a wiring electrode to connect the second electrode to power wirings, ensuring electrical contact while preventing film separation through the formation of a stair gap and specific pattern layer placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the cathode and power wiring are placed in close proximity in non-display areas to reduce device size, then the device dimensions are reduced, but film separation occurs at the cathode contact portion causing display defects
Solution Approach 1:
The patent introduces an intermediary structure consisting of contact holes through insulating layers and wiring electrodes that mediate between the cathode and power wiring. This intermediary connection path allows the cathode and power wiring to be positioned closer together while preventing direct contact that would cause film separation, thus resolving the contradiction between device size reduction and film separation resistance.
Solution Approach 2:
The patent utilizes vertical stacking of multiple insulating layers with contact holes penetrating through them, transitioning from a planar arrangement to a three-dimensional structure. This dimensional change allows the cathode and power wiring to be in close horizontal proximity while maintaining vertical separation through the insulating layers, enabling size reduction without film separation.
2Reliability
If multiple insulating layers with contact holes are introduced to prevent film separation, then film separation resistance is improved, but the device structure becomes more complex
Solution Approach 1:
The insulating layers serve multiple functions simultaneously: they provide electrical isolation between conductive elements, structurally support the contact holes for wiring connections, and prevent film separation at the cathode contact portion. This multi-functionality reduces the need for separate dedicated structures, thereby limiting the increase in device complexity while achieving improved film separation resistance.
Data Source
AI summary
An organic light-emitting diode (OLED) display and a method of manufacturing an OLED display are disclosed. In one aspect, the display includes a display substrate including a display area and a non-display area surrounding the display area. Also included is a thin film transistor (TFT) formed over the display area and including a semiconductor active layer, a gate electrode, a source electrode, and a drain electrode. An OLED is formed over the display area and includes a first electrode electrically connected to the TFT, an intermediate layer, and a second electrode. A plurality of power wirings are formed over the non-display area and are electrically connected to the second electrode so as to form an electrode contact. The display also includes a plurality of insulating layers formed over the display substrate and configured to insulate the TFT, the OLED, and the power wirings from one another.