Organic Photoelectric Conversion Layer With Halogen Interlayer Stability
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Solution Overview
Problem
Solid-state imaging elements with organic semiconductor materials face challenges in enhancing electric characteristics and responsivity due to modifications of organic materials during film formation, particularly with the desorption of halogen atoms from the photoelectric conversion layer affecting dark current characteristics.
Innovation Solution
Incorporating an upper inter-layer with a halogen atom concentration between 0.01 volume % and 0.05 volume % between the top-electrode and the photoelectric conversion layer, or using an organic semiconductor material with a halogen atom binding energy of 5.4 eV or higher, and maintaining a distance of 5 nm to 20 nm between the top-electrode and the photoelectric conversion layer to suppress material modification during film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a photoelectric conversion layer using organic semiconductor material is formed, then charge generation and transport efficiency is improved, but modification of organic materials during film formation occurs causing deterioration of electric characteristics
Solution Approach 1:
An upper inter-layer is introduced as an intermediary between the top-electrode and the photoelectric conversion layer. This inter-layer acts as a protective barrier that prevents modification of the organic semiconductor materials during film formation processes, while still allowing efficient charge transport. The inter-layer contains organic semiconductor material with halogen atoms at a specific concentration (0.01 volume % or more and less than 0.05 volume %), which suppresses material modification without significantly impeding charge generation and transport efficiency.
2Stability of the object's composition
If halogen atoms are present in the photoelectric conversion layer, then material stability is improved, but desorption of halogen atoms during film formation occurs causing modification of organic materials
Solution Approach 1:
The concentration of halogen atoms in the upper inter-layer is precisely controlled within a specific range (0.01 volume % or more and less than 0.05 volume %). This parameter optimization ensures that enough halogen atoms are present to stabilize the organic semiconductor material and suppress desorption during film formation, while preventing excessive halogen content that would cause harmful desorption effects and material modification.
3Device complexity
If the top-electrode is positioned close to the photoelectric conversion layer, then device structure is simplified, but material modification occurs during film formation
Solution Approach 1:
The device structure is segmented by introducing an upper inter-layer between the top-electrode and the photoelectric conversion layer. This segmentation adds a thin functional layer that physically separates the electrode from the sensitive organic semiconductor material, preventing direct interaction and modification during film formation. Although this adds a layer, the overall device complexity remains manageable as the inter-layer can be formed using standard deposition techniques.
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
These measures improve the electric characteristics and responsivity of the solid-state imaging elements by reducing dark current and enhancing the stability of organic materials, leading to better performance in charge generation and transport.
Implementation Method 1
the desorption of halogen atoms from the photoelectric conversion layer affecting dark current characteristics
Implementation Method 2
a photoelectric conversion layer that uses an organic semiconductor material
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
[Solving Means] A first solid-state imaging element according to an embodiment of the present disclosure includes a bottom-electrode; a top-electrode opposed to the bottom-electrode; a photoelectric conversion layer provided between the bottom-electrode and the top-electrode and including a first organic semiconductor material; and an upper inter-layer provided between the top-electrode and the photoelectric conversion layer, and including a second organic semiconductor material having a halogen atom in a molecule at a concentration in a range from 0 volume % or more to less than 0.05 volume %.