Light Emitting Device Electrode Segmentation for Uniformity
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Solution Overview
Problem
The existing light emitting devices face challenges with luminance non-uniformity due to variations in electric potential across the substrate, caused by electrode resistance, and the need for a larger window frame region to accommodate positioning tolerance, which hinders size reduction and increases the risk of electrode breakage and moisture ingress.
Innovation Solution
The design includes a light emitting device with a second electrode that extends beyond the auxiliary electrode and insulating layer, reducing resistance and positioning tolerance, and using a highly accurate positioning mechanism for the auxiliary electrode to minimize luminance non-uniformity and prevent moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the auxiliary electrode is formed using a highly accurate positioning mechanism to reduce resistance, then luminance uniformity is improved, but the positioning tolerance requirement increases and manufacturing complexity increases
Solution Approach 1:
The electrode system is segmented into two functional parts: the auxiliary electrode that extends through gaps between light emitting elements (requiring high positioning accuracy) and the common electrode that covers the entire effective region (allowing larger positioning tolerance). This segmentation allows each part to be optimized for its specific function while managing positioning requirements differently.
Solution Approach 2:
Different regions of the electrode system have different quality requirements. The auxiliary electrode in the gap regions requires high positioning precision and low resistance material properties, while the common electrode in the effective region can tolerate larger positioning variations. This local differentiation resolves the contradiction by applying strict precision only where necessary.
2Area of stationary object
If the window frame region is reduced to minimize device size, then the area is reduced, but the positioning tolerance for the common electrode becomes more critical
Solution Approach 1:
The electrode function is segmented between the auxiliary electrode (handling positioning-critical gap regions) and the common electrode (handling the effective emission region). This allows the window frame region to be minimized while the auxiliary electrode absorbs the positioning tolerance requirements, protecting the common electrode from stringent positioning demands.
Solution Approach 2:
The auxiliary electrode acts as an intermediary element that mediates between the common electrode and the gap regions. It absorbs the positioning tolerance requirements and electrical resistance issues, allowing the common electrode to be formed with larger tolerance while the auxiliary electrode compensates for positioning variations to maintain overall system performance.
3Reliability
If the insulating layer has a step structure to isolate electrodes from circuit elements, then electrical insulation is improved, but the risk of electrode breakage or cracking increases
Solution Approach 1:
The auxiliary electrode serves as an intermediary that is positioned to overlap the insulating layer step, absorbing the mechanical stress and preventing crack propagation to the common electrode. This intermediary positioning protects the common electrode from breakage while maintaining the necessary electrical insulation through the stepped insulating layer.
Data Source
AI summary
A light emitting device includes a substrate, a light emitting elements that have a first electrode, a second electrode and a light emitting layer, an element layer, an auxiliary electrode that is electrically connected to the second electrode, and an insulating layer. The second electrode is commonly provided for the light emitting elements. The insulating layer has a portion arranged in a lower layer under the second electrode and the auxiliary electrode. The auxiliary electrode is formed partly in a peripheral region of the light emitting device. In the peripheral region, an end portion of the second electrode is located on an inner side along a plane of the substrate than an end portion of the auxiliary electrode and located on an outer side than an end portion of the insulating layer.