Hole Blocking Layer with Fullerene Composite for Organic Photoelectric Conversion
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Solution Overview
Problem
Existing organic photoelectric conversion devices with hole blocking layers using fullerenes or fullerene derivatives suffer from slow response speed and residual image issues due to reduced carrier transport rates, which compromise sensitivity and signal-to-noise ratio.
Innovation Solution
Incorporating a hole blocking layer with a fullerene or fullerene derivative and a transparent hole transport material having an ionization potential of 5.5 eV or more, with a volume content of 30-80% and a thickness of 5-100 nm, to suppress hole injection from electrodes while maintaining carrier transport efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hole blocking layer using fullerene or fullerene derivative is provided to suppress hole injection from electrode, then dark current is reduced and S/N ratio is improved, but response speed becomes slow and residual image occurs
Solution Approach 1:
The hole blocking layer is formed as a composite material combining fullerene (or fullerene derivative) with electron transport material. This composite structure allows the layer to simultaneously block holes effectively (improving S/N ratio) while maintaining carrier transport capability (preserving response speed). The synergistic combination of materials with different properties resolves the contradiction between hole blocking performance and carrier transport efficiency.
Solution Approach 2:
The invention optimizes specific parameters of the hole blocking layer including the volume content ratio of fullerene to electron transport material (1:4 to 4:1), layer thickness (5-100 nm), and ionization potential of the electron transport material (5.5 eV or more). By adjusting these parameters, the layer achieves optimal balance between hole blocking capability and carrier transport rate, resolving the speed-S/N ratio contradiction.
2Reliability
If hole blocking layer thickness is increased to improve hole blocking performance, then dark current suppression is enhanced, but carrier transport rate is reduced
Solution Approach 1:
The invention optimizes the thickness parameter of the hole blocking layer within 5-100 nm range. This controlled thickness provides sufficient hole blocking performance to suppress dark current while maintaining adequate carrier transport rate. The specific thickness range balances the conflicting requirements of dark current suppression and carrier transport efficiency.
Solution Approach 2:
The composite structure of fullerene and electron transport material enables the hole blocking layer to achieve effective hole blocking at reduced thickness compared to pure fullerene layers. The electron transport material component maintains carrier transport pathways, allowing thinner layers that suppress dark current without severely impacting carrier transport rate.
3Reliability
If only electron transport material is used in hole blocking layer, then hole injection is suppressed, but hole transport rate within layer is reduced
Solution Approach 1:
The hole blocking layer combines fullerene (excellent hole blocking properties) with electron transport material (good carrier transport properties). This composite structure suppresses hole injection from the electrode while maintaining adequate hole transport rate within the layer. The electron transport material provides pathways that prevent carrier accumulation and maintain response speed.
Solution Approach 2:
The invention creates local quality differentiation within the hole blocking layer by combining materials with complementary properties. Fullerene provides localized hole blocking at the electrode interface, while electron transport material provides localized carrier transport pathways throughout the layer. This spatial differentiation of functions resolves the contradiction between hole injection suppression and hole transport rate.
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 enhances sensitivity, maintains a favorable signal-to-noise ratio, and achieves fast response speeds by effectively blocking holes without reducing carrier transport rates, thereby improving overall photoelectric conversion device performance.
Implementation Method 1
a charge blocking layer for preventing carrier (charge) injection from an electrode due to an external electric field is provide between the electrode and the organic photoelectric conversion layer
Implementation Method 2
hole blocking layer that includes a fullerene and/or a fullerene derivative and an insulating material
Implementation Method 3
an organic photoelectric conversion device having a photoelectric conversion layer formed of an organic layer
Data Source
AI summary
An organic photoelectric conversion device having a pair of electrodes and a light receiving layer which includes at least a photoelectric conversion layer and is sandwiched by the electrodes, the device including an electron blocking layer provided between the photoelectric conversion layer and one of the electrodes, and a hole blocking layer provided between the photoelectric conversion layer and the other of the electrodes, in which the hole blocking layer is a layer that includes a fullerene and/or a fullerene derivative and a transparent hole transport material having an ionization potential of 5.5 eV or more.