Organic Photodiode Buffer Layer for Lower Leakage and Voltage
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Solution Overview
Problem
Organic photoelectronic devices using organic materials face challenges with high driving voltage, leakage current, and efficiency deterioration due to recombination behavior and low photoelectronic conversion efficiency compared to silicon-based devices.
Innovation Solution
The use of a photoelectronic conversion layer with a p-n junction and a buffer layer comprising a first light absorbing material and a non-absorbing material, where the buffer layer includes multiple layers with varying compositions of the light absorbing and non-absorbing materials, and a thickness of 2 nm to 40 nm, to reduce driving voltage and leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic material is used to replace silicon in photodiodes, then sensitivity is improved and color filter functionality is integrated, but photoelectronic conversion efficiency deteriorates due to recombination behavior
Solution Approach 1:
A buffer layer comprising a first light absorbing material and a non-absorbing material is introduced between the electrode and the photoelectronic conversion layer. This buffer layer acts as an intermediary that modifies charge carrier transport, reduces recombination losses at the interface, and improves overall photoelectronic conversion efficiency while preserving the sensitivity advantages of organic materials.
Solution Approach 2:
The buffer layer changes the physical and chemical parameters at the electrode-photoelectronic conversion layer interface by incorporating both light absorbing and non-absorbing materials in specific ratios. This parameter modification optimizes charge separation and transport properties, reducing recombination behavior and improving conversion efficiency without sacrificing the inherent sensitivity of organic photoelectronic materials.
2Measurement precision
If pixel size is reduced to achieve high resolution, then image quality is improved, but absorption area decreases leading to deteriorated sensitivity
Solution Approach 1:
The buffer layer uses a composite material system combining light absorbing and non-absorbing materials. The light absorbing component enhances photon capture in the reduced pixel area, while the non-absorbing component optimizes charge transport. This composite approach allows small pixels to maintain both high resolution and adequate sensitivity through synergistic material properties.
3Loss of energy
If buffer layer thickness is increased to improve charge transport, then photoelectronic conversion efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The buffer layer thickness is optimized to a specific range (2 nm to 40 nm) where it achieves sufficient charge transport and recombination reduction without excessive complexity. This parameter optimization balances performance improvement with manufacturing feasibility, ensuring the buffer layer is thin enough for simple fabrication but thick enough to provide the necessary functional benefits.
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
This configuration lowers driving voltage and leakage current while enhancing photoelectronic conversion efficiency by improving charge movement and reducing recombination, thereby improving overall device performance.
Implementation Method 1
A photoelectronic device may convert light into an electrical signal using photoelectric effects
Implementation Method 2
An organic material has a relatively high extinction coefficient and selectively absorbs light in a particular wavelength region depending on a molecular structure
Data Source
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AI summary
An organic photoelectronic device may include a photoelectronic conversion layer between a first electrode and a second electrode and a buffer layer on the photoelectronic conversion layer. The photoelectronic conversion layer may be between a first electrode and a second electrode, and the buffer layer may be between the first electrode and the photoelectronic conversion layer. The photoelectronic conversion layer may include at least a first light absorbing material and a second light absorbing material configured to provide a p-n junction. The buffer layer may include the first light absorbing material and a non-absorbing material associated with a visible wavelength spectrum of light. The non-absorbing material may have a HOMO energy level of about 5.4 eV to about 5.8 eV. The non-absorbing material may have an energy bandgap of greater than or equal to about 2.8 eV.