Nitride Buffer Layer Electron Blocking in Optoelectronic Devices
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Solution Overview
Problem
Organic optoelectronic devices suffer from low external quantum efficiency and high dark current due to internal impurities, leading to reduced sensitivity and accuracy in the visible light region, which affects their performance and noise levels.
Innovation Solution
Incorporating a buffer layer with specific nitride materials, such as silicon nitride or silicon oxynitride, between the electrodes and the photoelectric conversion layer, with tailored energy bandgap and thickness to effectively block electrons and reduce dark current, while maintaining photoelectric conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buffer layer with nitride materials is introduced between the electrode and photoelectric conversion layer, then dark current is reduced and sensitivity is improved, but device structure becomes more complex
Solution Approach 1:
A buffer layer comprising nitride materials (such as silicon nitride or silicon oxynitride) is introduced as an intermediary between the second electrode and the photoelectric conversion layer. This buffer layer acts as a mediator that blocks electrons from the electrode from entering the photoelectric conversion layer, thereby reducing dark current while maintaining the overall functional integrity of the device.
Solution Approach 2:
The buffer layer is designed with specific parameter ranges: a thickness of 1 nm to 30 nm and an energy bandgap of -3.8 eV to -1.5 eV. By optimizing these parameters, the buffer layer effectively blocks electrons (reducing dark current) while allowing sufficient light transmission and maintaining photoelectric conversion efficiency, thus resolving the contradiction between reliability improvement and device complexity.
2Reliability
If the buffer layer thickness is increased to block more electrons, then dark current is reduced, but light transmission and photoelectric conversion efficiency are reduced
Solution Approach 1:
The buffer layer thickness is optimized within the range of 1 nm to 30 nm. This parameter optimization ensures that the layer is thick enough to effectively block electrons and reduce dark current, while remaining thin enough to allow sufficient light transmission and maintain high photoelectric conversion efficiency. The energy bandgap is also optimized to -3.8 eV to -1.5 eV to achieve effective electron blocking.
Solution Approach 2:
The buffer layer comprises nitride materials such as silicon nitride (SiNx) or silicon oxynitride (SiOyNz), which possess unique properties combining high electron blocking capability with good optical transparency. These composite material characteristics enable the buffer layer to simultaneously reduce dark current and maintain photoelectric conversion efficiency without requiring excessive thickness.
3Ease of manufacture
If organic materials are used in the photoelectric conversion layer, then device flexibility and manufacturing are improved, but external quantum efficiency decreases and dark current increases due to internal impurities
Solution Approach 1:
The buffer layer comprising nitride materials serves as a protective intermediary between the electrode and the organic photoelectric conversion layer. It blocks electrons from the electrode from entering the organic layer, thereby preventing electron-induced degradation and reducing dark current caused by internal impurities in the organic materials, while allowing the organic materials to maintain their manufacturing advantages.
Solution Approach 2:
The buffer layer is designed with an energy bandgap of -3.8 eV to -1.5 eV, which is specifically optimized to block electrons while being transparent to visible light. This parameter optimization ensures that organic optoelectronic devices can achieve high external quantum efficiency and low dark current, resolving the contradiction between ease of manufacture and reliability.
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 significantly reduces dark current and enhances sensitivity and performance of optoelectronic devices, improving their external quantum efficiency and reducing noise, as demonstrated by the reduced current densities and increased efficiency across various examples.
Implementation Method 1
a buffer layer between the anode and the photoelectric conversion layer, wherein the buffer layer includes a nitride
Implementation Method 2
excitons are generated in a photoelectric conversion layer by photons from an external light source; the excitons are separated into electrons and holes
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An optoelectronic device (100) includes a first electrode (20) and a second electrode (10) facing each other, a photoelectric conversion layer (30) between the first electrode and the second electrode and a buffer layer (40) between the photoelectric conversion layer (30) and the second electrode (10), wherein the buffer layer (40) includes a nitride selected from silicon nitride (SiNx, 0 < x < 1), silicon oxynitride (SiOyNz, 0 < y < 0.5, 0 < z < 1), and a combination thereof.