Organic Buffer Layer in Photoelectric Conversion for Low Dark Current
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Solution Overview
Problem
Existing photoelectric conversion devices face challenges with reduced sensitivity due to small pixel sizes, high binding energy, and recombination behavior of organic materials, making it difficult to accurately predict and control their characteristics for efficient photoelectric conversion.
Innovation Solution
A photoelectric conversion device is designed with a first and second electrode, a photoelectric conversion layer comprising a p-type and n-type semiconductor, and an organic buffer layer with an organic buffer material having at least three carbazole moieties, optimizing energy level differences to enhance charge carrier extraction and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic material is used to replace silicon photodiode, then sensitivity and integration are improved, but remaining charge carriers and dark current increase due to high binding energy and recombination behavior
Solution Approach 1:
An organic buffer layer is introduced as an intermediary between the electrode and the organic photodiode. This buffer layer mediates the interaction between the electrode and the photodiode, facilitating efficient charge carrier extraction while blocking harmful effects. The buffer layer's energy levels are specifically designed to create favorable energy offsets for electron extraction, thereby reducing remaining charge carriers and dark current without compromising sensitivity.
Solution Approach 2:
The energy level parameters of the organic buffer layer are optimized to resolve the contradiction. By selecting materials with specific HOMO and LUMO energy levels, the patent creates appropriate energy offsets at the interfaces. The LUMO level of the buffer layer is positioned to facilitate electron extraction, while the HOMO level is positioned to block holes, thereby reducing dark current and remaining charge carriers while maintaining high sensitivity.
2Measurement precision
If pixel size is reduced to achieve higher resolution, then sensor resolution is improved, but absorption area decreases leading to deteriorated sensitivity
Solution Approach 1:
The patent optimizes the energy level parameters of the organic buffer layer to enhance charge carrier extraction efficiency. By creating favorable energy offsets, the buffer layer ensures that even in small pixels with limited absorption area, the generated charge carriers are efficiently extracted, thereby maintaining sensitivity despite reduced pixel size.
3Productivity
If organic buffer layer with optimized energy levels is introduced, then charge carrier extraction and thermal stability are improved, but device complexity increases
Solution Approach 1:
The organic buffer layer serves as a simple intermediary component that provides multiple functions simultaneously: it facilitates charge carrier extraction, blocks harmful carriers, and enhances thermal stability. By introducing this single buffer layer, the patent achieves multiple improvements without significantly increasing device complexity.
Solution Approach 2:
The organic buffer layer is designed to perform multiple functions within a single component: it acts as a charge carrier extraction layer, a blocking layer for harmful carriers, and a thermal stability enhancer. This multi-functionality allows the patent to achieve improved charge carrier extraction and thermal stability without proportionally increasing device complexity.
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 proposed solution effectively reduces remaining charge carriers and dark current, while improving photoelectric conversion efficiency, charge carrier extraction characteristics, and thermal stability of the device.
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
Implementation Method 3
The organic buffer material includes at least three carbazole moieties... improving photoelectric conversion efficiency, charge carrier extraction characteristics, and thermal stability
Data Source
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.