Organic Light-Emitting Apparatus Insulating Layer Optimization
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Solution Overview
Problem
Conventional organic light-emitting apparatuses face issues with non-uniform emission luminance and reduced pixel aperture ratio due to conductive layers affecting capacitance and optical interference, especially when dealing with organic light-emitting elements of different emission colors.
Innovation Solution
An organic light-emitting apparatus with a conductive layer between the substrate and the first electrode, electrically connected to a light-transmissive second electrode, and an insulating layer varying in thickness or material depending on emission colors to optimize light emission for each color, while minimizing voltage drop and capacitance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive layer is provided below the pixel electrode to reduce voltage drop, then conductivity is improved, but capacitance is generated between the conductive layer and pixel electrode causing non-uniform emission luminance
Solution Approach 1:
An insulating layer is introduced as an intermediary between the first electrode (pixel electrode) and the conductive layer. This insulating layer prevents direct electrical contact, thereby eliminating the harmful capacitance effect while still allowing the conductive layer to function as a reflective base that improves overall conductivity and reduces voltage drop in the electrode structure.
2Object-generated harmful factors
If the insulating layer thickness is increased to reduce capacitance, then capacitance effect is reduced, but optical interference changes affecting light emission of different colors
Solution Approach 1:
The thickness of the insulating layer is precisely controlled and optimized as a critical parameter. By adjusting the thickness within a specific range, the patent simultaneously achieves two objectives: maintaining sufficiently low capacitance effect to ensure uniform emission luminance, and preserving appropriate optical interference conditions to enhance light extraction efficiency for different emission colors.
Solution Approach 2:
The insulating layer is designed with color-specific optimization. Different regions corresponding to different emission colors (red, green, blue sub-pixels) may have different insulating layer thicknesses, allowing each color to be optimized independently for both capacitance reduction and light emission enhancement.
3Illumination intensity
If a transparent conductive film is used for the common electrode, then light transmission is improved, but sheet resistance causes voltage drop and non-uniform current distribution
Solution Approach 1:
The electrode structure employs a composite configuration combining transparent conductive films with highly reflective metal layers. The transparent conductive film (such as ITO) provides light transmission, while the underlying metal layer provides high conductivity and low sheet resistance. This composite structure achieves both light transmission and voltage uniformity by leveraging the complementary properties of different materials.
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 ensures uniform emission luminance and improved light extraction efficiency for organic light-emitting elements of different colors by addressing voltage drop, capacitance, and optical interference, maintaining high pixel aperture ratio and enhancing optical path differences for enhanced light emission.
Implementation Method 1
an organic EL element having light-emitting layers formed of an organic light-emitting material... electrons injected from the cathode into the EL emission layer and holes injected from the anode to the EL emission layer are recombined to generate excitons. The organic EL element emits light by utilizing light emitted when the excitons return to a ground state.
Implementation Method 2
the influence of optical interference is not considered in Japanese Patent Application Laid-Open No. 2005-158493. In particular, in the case of an organic light-emitting apparatus with organic light-emitting elements of different emission colors, the conditions of optical interference vary depending on the emission color
Implementation Method 3
an insulating layer which is varied in one of thickness and material depending on the emission colors... by addressing voltage drop, capacitance, and optical interference, maintaining high pixel aperture ratio and enhancing optical path differences for enhanced light emission
Data Source
AI summary
Provided is an organic light-emitting apparatus which can allow each of a plurality of organic light-emitting elements of different emission colors to emit light under optimum conditions. The organic light-emitting apparatus includes: a substrate; a plurality of organic light-emitting elements of different emission colors disposed on the substrate and each having formed sequentially on the substrate, a first electrode formed independently for each of the plurality of organic light-emitting elements, an organic functional layer, and a light-transmissive second electrode continuously formed extending over the plurality of organic light-emitting elements; a conductive layer formed between the substrate and the first electrode and electrically connected to the second electrode; and an insulating layer formed between the conductive layer and the first electrode, in which the insulating layer is different in at least one of thickness and material for each of the different emission colors.