Dual-Layered Buffer Layer for Organic Photodiode Dark Current Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic photodiodes suffer from higher dark current and lower external quantum efficiency compared to silicon photodiodes due to impurities, leading to increased current leakage and decreased sensitivity, which is not adequately addressed by existing buffer layers.
Innovation Solution
A photodiode with a dual-layered buffer layer structure comprising an organic layer and an inorganic layer, where the organic layer is closer to the anode and includes materials like 2TNATA, and the inorganic layer includes MoOx, improving dark current reduction and external quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a buffer layer is added between the anode and photoelectric layer to reduce dark current, then dark current is reduced, but the reduction degree is insufficient
Solution Approach 1:
The buffer layer is divided into multiple sub-layers with different materials and functions. Specifically, it includes a first buffer layer (e.g., MoO3) adjacent to the anode for hole extraction, a second buffer layer (e.g., Alq3) for electron blocking, and optionally a third buffer layer (e.g., BCP) for additional electron blocking. This segmentation allows each sub-layer to optimize its function, achieving significant dark current reduction that a single-layer buffer cannot accomplish.
Solution Approach 2:
The buffer layer employs composite material structure combining different organic and inorganic materials. The inorganic layer (e.g., MoO3) provides excellent hole extraction capability, while the organic layers (e.g., Alq3, BCP) provide superior electron blocking properties. This composite approach leverages the complementary strengths of different material types to achieve optimal dark current reduction performance.
2Volume of moving object
If organic photodiode uses organic materials with higher absorption coefficient, then size can be reduced, but external quantum efficiency for visible light becomes lower than silicon photodiode
Solution Approach 1:
The patent optimizes the thickness parameters of the photoelectric conversion layer and buffer layers to balance absorption efficiency and quantum efficiency. By carefully controlling layer thicknesses (e.g., photoelectric conversion layer: 50-200 nm, buffer layers: 10-100 nm each), the device achieves sufficient light absorption in a compact size while maintaining high external quantum efficiency through optimized optical and electrical parameters.
Solution Approach 2:
The buffer layers act as intermediaries between the anode and photoelectric conversion layer, facilitating efficient charge extraction and reducing recombination losses. This intermediary structure improves electron-hole separation efficiency, thereby enhancing external quantum efficiency without increasing device size, as the buffer layers are ultra-thin (10-100 nm) and do not significantly add to the overall device volume.
3Volume of moving object
If organic photodiode uses organic materials, then size can be reduced, but dark current increases due to impurity in organic materials
Solution Approach 1:
The buffer layer is segmented into multiple functional sub-layers that collectively address impurity-related dark current issues. The first buffer layer (inorganic MoO3) provides a clean interface with the anode, the second buffer layer (organic Alq3) blocks electrons, and the third buffer layer (organic BCP) provides additional electron blocking. This segmentation isolates and addresses different sources of dark current generated by impurities in organic materials.
Solution Approach 2:
The composite buffer layer structure combines inorganic and organic materials to counteract the harmful effects of organic material impurities. The inorganic MoO3 layer provides excellent interface quality and hole extraction, while the organic Alq3 and BCP layers provide electron blocking. This composite approach compensates for impurity-related dark current in organic materials, achieving low dark current in a compact organic photodiode structure.
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 dual-layered buffer layer significantly reduces dark current and enhances external quantum efficiency, maintaining performance even at elevated temperatures and over extended storage periods.
Implementation Method 1
a photoelectric conversion layer disposed between the anode and the cathode
Implementation Method 2
a buffer layer disposed between the photoelectric conversion layer and the anode and having a dual-layered structure including an organic layer and an inorganic layer
Data Source
AI summary
A photodiode may include an anode, a cathode, a photoelectric conversion layer between the anode and the cathode, and a buffer layer between the photoelectric conversion layer and the anode. The buffer layer may have a dual-layered structure including an organic layer and an inorganic layer.