Organic Photodiode Layer Structure for Filterless Multi-Spectral Sensing
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Solution Overview
Problem
Existing organic photodiodes exhibit a single absorption spectrum determined by the inherent light absorption characteristics of organic materials, limiting their photoelectric conversion characteristics to a single profile, and require color filters for wavelength selectivity.
Innovation Solution
An organic photodiode design incorporating a reflective layer, semi-transmissive layer, and a photoelectric conversion layer with a buffer layer, allowing for multiple external quantum efficiency (EQE) spectra with narrow full width at half maximum, enabling wavelength selectivity without external color filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single absorption spectrum is used in organic photodiodes, then the device structure is simple, but the photoelectric conversion characteristics are limited to a single profile
Solution Approach 1:
The device is segmented into multiple functional layers including a reflective layer, semi-transmissive layer, buffer layer, and photoelectric conversion layer. This segmentation enables the generation of multiple EQE spectra with narrow FWHM by creating distinct optical paths and interference patterns within each layer, thereby achieving multi-profile photoelectric conversion characteristics without requiring multiple separate photodiode devices.
Solution Approach 2:
The invention transitions from a single absorption spectrum (one-dimensional characteristic) to multiple EQE spectra (multi-dimensional characteristics) by introducing vertical layering and controlling optical interference in the vertical dimension. The buffer layer thickness and refractive index are optimized to create constructive and destructive interference patterns that generate distinct EQE peaks at different wavelengths, effectively adding spectral dimensionality to the photoelectric conversion response.
2Adaptability or versatility
If color filters are added for wavelength selectivity, then wavelength selectivity is achieved, but the device complexity increases
Solution Approach 1:
The invention merges the functions of color filtering and photoelectric conversion into a single integrated structure. The buffer layer and electrode layers are designed to provide both the wavelength-selective filtering function and the photoelectric conversion function simultaneously, eliminating the need for separate color filter components. The optical interference effects in the buffer layer create wavelength selectivity while the photoelectric conversion layer converts the selected wavelengths to electrical signals in one unified device.
Solution Approach 2:
The buffer layer serves multiple functions: it provides optical interference for wavelength selectivity, acts as an electrical buffer for charge transport, and contributes to the overall device structure. This multi-functionality reduces the need for additional dedicated color filter layers, as the buffer layer simultaneously performs both optical filtering and electrical buffering roles, thereby reducing overall device complexity while maintaining wavelength selectivity.
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 design achieves multiple EQE spectra with distinct peaks and intervals, enhancing photoelectric conversion efficiency and enabling applications in multi-spectral and hyperspectral image sensors and cameras.
Implementation Method 1
a first electrode including a reflective layer
Implementation Method 2
a photoelectric conversion layer between the first electrode and the second electrode and including an organic light absorbing material
Implementation Method 3
a second electrode including a semi-transmissive layer
Data Source
AI summary
An organic photodiode includes a first electrode including a reflective layer, a second electrode including a semi-transmissive layer, a photoelectric conversion layer between the first electrode and the second electrode and including an organic light absorbing material, and a buffer layer that is at least one of between the reflective layer and the photoelectric conversion layer or between the semi-transmissive layer and the photoelectric conversion layer. The organic photodiode is configured to exhibit at least three external quantum efficiency (EQE) spectra in a wavelength region of about 380 nm to about 3000 nm and each EQE spectrum of the at least three EQE spectra has a full width at half maximum of about 2 nm to about 100 nm.