Quantum Dot Photoelectric Conversion Layer with Organic Matrix

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Solution Overview

Problem

Photoelectric conversion elements using quantum dots in the long-wavelength region suffer from increased dark current and residual images due to oxidation and aggregation, which are not effectively addressed by existing technologies.

Innovation Solution

A photoelectric conversion element comprising a quantum dot and an organic compound, where specific mobility and ionization potential conditions are met, along with an interface layer to reduce dark current and residual images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If quantum dots are used for long-wavelength photoelectric conversion, then sensitivity in the long-wavelength region is improved, but dark current increases due to oxidation and aggregation

Engineering Contradiction:

Improvesensitivity in the long-wavelength regionVSAvoiddark current

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

An organic compound is introduced as an intermediary substance between quantum dots to prevent direct contact and aggregation. The organic compound forms a protective interface that suppresses oxidation while maintaining photoelectric conversion efficiency, thereby reducing dark current caused by aggregation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The photoelectric conversion layer is designed as a composite material system containing quantum dots dispersed in an organic compound matrix. This composite structure combines the long-wavelength sensitivity of quantum dots with the stabilizing properties of the organic compound, preventing oxidation and aggregation while maintaining reliability

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If quantum dots with large particle diameter are used for long-wavelength sensitivity, then sensitivity in the long-wavelength region is improved, but aggregation occurs due to large surface area

Engineering Contradiction:

Improvesensitivity in the long-wavelength regionVSAvoidaggregation

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The organic compound acts as a spacer and protective layer between quantum dot particles, preventing them from aggregating despite their large surface area. This intermediary substance maintains particle dispersion while allowing the quantum dots to retain their long-wavelength sensitivity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the physical and chemical parameters of the quantum dot environment by introducing the organic compound, which modifies surface interactions and prevents aggregation while preserving the optical properties necessary for long-wavelength detection

Inventive Principle:

Principle #35Parameter changes

3Productivity

If both bulk semiconductor and quantum dot have photoelectric conversion capability, then photoelectric conversion efficiency is improved, but carrier inflow from bulk semiconductor causes recombination and suppresses efficiency

Engineering Contradiction:

Improvephotoelectric conversion efficiencyVSAvoidrecombination loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The bulk semiconductor component is extracted from the photoelectric conversion layer, leaving only quantum dots dispersed in the organic compound. This eliminates the source of carrier inflow and recombination loss while maintaining photoelectric conversion efficiency through the quantum dot-organic compound system

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The photoelectric conversion layer is designed with localized quantum dot structures embedded in the organic compound matrix, creating specific regions for photoelectric conversion that avoid the harmful carrier inflow effects from bulk semiconductor while maintaining high efficiency

Inventive Principle:

Principle #3Local quality

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 solution effectively reduces dark current and residual images, enhancing photoelectric conversion efficiency and sensitivity in the long-wavelength region.

Implementation Method 1

a photoelectric conversion element includes a first electrode, a photoelectric conversion layer, and a second electrode, in this order

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 2

μhorg (cm2/Vs): hole mobility of the organic compound in the photoelectric conversion layer

Methodology Applied

Scientific EffectCharge carrier transport: Conduction (electrical)

Data Source

PatentUS12389737B2Photoelectric conversion element

Publication Date: 2025.08.12 CANON KK

AI summary

A photoelectric conversion element including a first electrode, a photoelectric conversion layer, and a second electrode, in this order, wherein the photoelectric conversion layer contains a quantum dot and an organic compound, satisfies formula (1), a predetermined carrier mobility, and a predetermined energy level, and reduces a residual image, E2>E1 formula (1). E1 (eV) is the energy at a short-wavelength edge in a wavelength region of light detected by the photoelectric conversion element. E2 (eV) is the band gap of the organic compound.