Photoelectric Conversion Layers Using Indolocarbazole for Low Dark Current
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Solution Overview
Problem
Existing photoelectric conversion devices for imaging applications, such as digital cameras and smartphones, face challenges in achieving higher sensitivity and resolution due to inefficiencies in light utilization and pixel resolution, particularly when using inorganic semiconductors.
Innovation Solution
The use of an indolocarbazole compound with a specific amine skeleton in the photoelectric conversion device to enhance charge separation and electron/hole mobility, improving the contrast ratio and reducing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic semiconductor is used for photoelectric conversion device, then device structure is well-established and can be manufactured, but light utilization efficiency is low and sensitivity is insufficient
Solution Approach 1:
The patent changes the material parameter from inorganic semiconductor to organic semiconductor, which fundamentally alters the light absorption characteristics and charge transport properties. This parameter change enables higher light utilization efficiency while maintaining functional device structure through careful selection of organic semiconductor materials with appropriate HOMO-LUMO energy levels.
Solution Approach 2:
The patent employs composite material structure by combining organic semiconductor layers with specific functional layers (hole blocking layer, electron blocking layer, electrodes) to create a hybrid photoelectric conversion device. This composite approach leverages the advantages of organic materials for light absorption while using carefully designed interface layers to optimize charge extraction and reduce recombination losses.
2Adaptability or versatility
If RGB color filters are disposed on light receiving part to obtain color image, then color imaging capability is achieved, but resolution is reduced and light utilization efficiency is low
Solution Approach 1:
The patent transitions from the conventional planar arrangement of RGB color filters to a vertical stacking configuration of multiple photoelectric conversion layers. This dimensional change from 2D plane to 3D stack enables each layer to capture specific wavelength ranges independently, achieving color imaging without compromising pixel resolution or light utilization efficiency.
Solution Approach 2:
The patent segments the photoelectric conversion function into multiple specialized layers, each optimized for specific wavelength ranges or charge transport functions. This segmentation allows parallel processing of different spectral components without spatial overlap, thereby maintaining high resolution while achieving full-color imaging capability.
3Productivity
If bias voltage is applied to accelerate charge separation and movement, then photoelectric conversion efficiency is improved, but leakage current from electrodes increases
Solution Approach 1:
The patent introduces intermediary functional layers (hole blocking layer and electron blocking layer) positioned between the photoelectric conversion layer and electrodes. These intermediary layers act as selective barriers that facilitate desired charge transport while blocking unwanted charge carriers, thereby reducing leakage current without significantly impeding the photoelectric conversion process.
Solution Approach 2:
The patent applies local quality optimization by assigning different functional properties to different regions of the device. The hole blocking layer and electron blocking layer are strategically positioned at specific interfaces where they provide localized charge selectivity. This spatial differentiation of material properties enables efficient charge separation while minimizing leakage pathways.
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 indolocarbazole compound enables high sensitivity and low dark current values, resulting in a photoelectric conversion device with improved contrast ratio and reduced leakage current.
Implementation Method 1
light having a desired wavelength is absorbed in the photoelectric conversion layer to generate an exciton, and then charge separation of the exciton generates a hole and an electron
Implementation Method 2
the hole and the electron move toward each electrode to convert the light into an electric signal
Data Source
AI summary
Provided is a material for a photoelectric conversion device for imaging and a photoelectric conversion device for imaging that achieve higher sensitivity and higher resolution. A material for a photoelectric conversion device represented by the general formula (1) or (2), and a photoelectric conversion device for imaging, including a photoelectric conversion layer and an electron blocking layer between two electrodes, wherein at least one of these layers contains the above material.The ring E independently represents a heterocyclic ring condensed with an adjacent ring at any position and represented by the formula (1a). Ar1, Ar2, Ar5, and Ar6 each independently represent a diarylamino group having 12 to 30 carbon atoms, an arylheteroarylamino group having 12 to 30 carbon atoms, a diheteroarylamino group having 12 to 30 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms, or a heteroaromatic group having 4 to 18 carbon atoms, and at least one of Ar1, Ar2, Ar5, or Ar6 represents the amino group or a group in which the amino group is further condensed.