Photoelectric Conversion Device with Carbazole Buffer Layer
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Solution Overview
Problem
Silicon photodiodes face challenges with deteriorated sensitivity due to small pixel sizes, and organic materials, while promising, are difficult to predict and control for accurate photoelectric conversion properties.
Innovation Solution
A photoelectric conversion device with a specific organic buffer layer having a defined energy level difference with p-type and n-type semiconductors, utilizing an organic buffer material with at least three carbazole moieties, reduces charge carriers and dark current, enhancing efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon photodiodes are used for photoelectric conversion, then the device structure is simple and manufacturing isๆ็, but sensitivity deteriorates due to small absorption area in small pixels
Solution Approach 1:
The patent changes the material parameter from silicon to organic material, which has fundamentally different optical properties including higher extinction coefficient, enabling effective light absorption in thinner layers and small pixel areas while maintaining or improving sensitivity
Solution Approach 2:
The patent uses composite material structure combining organic buffer layer with specific organic photoelectric conversion materials, where the buffer layer with tailored HOMO/LUMO energy levels interfaces with the photoelectric conversion layer to optimize charge carrier extraction and reduce recombination, thereby improving sensitivity
2Reliability
If organic materials are used to replace silicon photodiodes, then sensitivity and integration are improved, but it becomes difficult to predict and control photoelectric conversion characteristics due to high binding energy and recombination behavior
Solution Approach 1:
The patent systematically adjusts and optimizes critical parameters including HOMO and LUMO energy levels of the organic buffer layer, thickness of buffer layer, and molecular structure of organic materials to achieve desired photoelectric conversion characteristics, making the system controllable despite organic material complexity
Solution Approach 2:
The organic buffer layer acts as an intermediary between the electrode and the photoelectric conversion layer, mediating charge carrier transport and extraction. By carefully designing the buffer layer's energy levels (HOMO and LUMO), it facilitates efficient charge extraction while blocking recombination, thereby improving predictability and control of overall device characteristics
3Reliability
If organic buffer layer with specific energy levels is introduced, then charge carrier extraction and thermal stability are improved, but device structure becomes more complex
Solution Approach 1:
The organic buffer layer serves as a functional intermediary that simplifies the overall device performance by providing optimized charge carrier extraction pathways. Although it adds a layer, it eliminates the need for complex electrode structures or additional charge extraction layers, as the buffer layer itself performs multiple functions including charge extraction, energy level matching, and recombination prevention
Solution Approach 2:
The organic buffer layer performs multiple functions simultaneously: it provides energy level matching between electrode and photoelectric conversion layer, facilitates hole extraction (or electron extraction depending on configuration), prevents charge recombination, and enhances thermal stability. This multi-functionality reduces the need for additional specialized layers, making the overall structure more efficient despite the added layer
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 device effectively reduces remaining charge carriers and dark current, improving photoelectric conversion efficiency and charge carrier extraction characteristics, while maintaining thermal stability.
Implementation Method 1
A photoelectric conversion device converts light into an electrical signal using photoelectric effects
Implementation Method 2
A difference between a LUMO energy level of the organic buffer material and a LUMO energy level of the n-type semiconductor is greater than or equal to about 1.2 eV
Data Source
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AI summary
Disclosed are a photoelectric conversion device includes a first electrode and a second electrode, a photoelectric conversion layer between the first electrode and the second electrode, the photoelectric conversion layer including a p-type semiconductor and an n-type semiconductor, and an organic buffer layer between the first electrode and the photoelectric conversion layer, the organic buffer layer including an organic buffer material, wherein a difference between a LUMO energy level of the organic buffer material and a LUMO energy level of the n-type semiconductor is greater than or equal to about 1.2 eV and the organic buffer material includes at least three carbazole moieties, and a sensor, and an electronic device including the same.