Nanopatterned Electrode Light Absorption in Organic Image Sensors
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Solution Overview
Problem
Silicon photodiodes have limited sensitivity due to small absorption areas, necessitating the development of organic materials that can enhance light absorption and potentially replace both photodiodes and color filters in image sensors.
Innovation Solution
An organic photoelectronic device with a first electrode featuring nanopatterns arranged at regular intervals, which selectively reflects light to an active layer that absorbs light in specific wavelength regions, such as blue, red, and green, thereby increasing light absorbance without increasing the active layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If silicon photodiodes are used to achieve high resolution, then pixel size can be reduced, but light absorption area decreases and sensitivity deteriorates
Solution Approach 1:
The first electrode is designed with nanopatterns (protrusions and depressions) that create localized optical field enhancements at specific positions. This local structural modification increases light absorption in the active layer without requiring larger pixel areas, thus maintaining high resolution while improving sensitivity.
Solution Approach 2:
Instead of increasing absorption area in the planar dimension, the invention introduces vertical dimensionality through nanopatterns on the electrode surface. The protrusions and depressions create multiple light reflection paths and enhance optical path length within the active layer, effectively increasing absorption without increasing pixel footprint.
2Adaptability or versatility
If organic material is used to replace silicon photodiode and color filter, then sensitivity and integration can be improved, but light absorption efficiency needs enhancement
Solution Approach 1:
The nanopatterned first electrode creates localized optical field enhancements that concentrate light energy at specific positions within the active layer. This local field enhancement compensates for the inherently lower light absorption efficiency of organic materials, enabling effective light harvesting without increasing layer thickness or compromising device integration.
Solution Approach 2:
The nanopatterns on the first electrode create optical resonance effects that trap and concentrate light within the active layer. This optical 'vibration' or resonance enhances the interaction between light and organic material, significantly improving absorption efficiency despite the thin active layer required for device integration.
3Reliability
If active layer thickness is increased to improve light absorption, then absorption area increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Rather than uniformly increasing active layer thickness, the invention introduces local structural variations in the first electrode (nanopatterns). These localized features enhance light absorption through optical field concentration and multiple reflection paths, achieving high absorption efficiency without increasing overall device complexity or manufacturing difficulty.
Solution Approach 2:
The invention replaces the mechanical approach of simply thickening the active layer with an optical approach using nanopatterned electrodes. The optical field manipulation through sub-wavelength structures achieves enhanced light absorption without the mechanical complexity of thicker layers, maintaining device simplicity while improving performance.
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
The organic photoelectronic device enhances light absorbance, improving the efficiency of image sensors by selectively reflecting and absorbing light in targeted wavelength regions, thus overcoming the sensitivity limitations of silicon photodiodes.
Implementation Method 1
The first electrode may selectively reflect light to the active layer in a wavelength region absorbed by the active layer
Implementation Method 2
an active layer between the first electrode and the second electrode, the active layer absorbing light in at least one wavelength region of a visible ray region
Implementation Method 3
A photoelectronic device converts light into an electrical signal using photoelectronic effects
Data Source
AI summary
An organic photoelectronic device includes a first electrode having a plurality of nanopatterns arranged at a regular interval, a second electrode facing the first electrode and an active layer between the first electrode and the second electrode, the active layer absorbing light in at least one wavelength of a visible ray region.