Photoelectric Conversion Element With Graded Ligand Contacts

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Solution Overview

Problem

In photoelectric conversion elements, the presence of organic ligands between charge transport materials and electrodes forms electrostatic capacities, leading to prolonged retention of electric charges after the element is turned off.

Innovation Solution

A carrier transport layer with varying organic ligand distribution, ensuring a larger minimum distance between particles near the photoelectric conversion layer and a smaller distance near the electrode, facilitating better electrical contacts and reducing charge retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If organic ligands are present in the carrier transport layer to facilitate charge transport, then charge transport efficiency is improved, but electrostatic capacity forms between the carrier transport particles and electrode, leading to prolonged charge retention

Engineering Contradiction:

Improvecharge transport efficiencyVSAvoidcharge retention time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local quality by creating a non-uniform distribution of organic ligands within the carrier transport layer. Specifically, the ligand concentration is higher near the photoelectric conversion layer and lower near the electrode, allowing different regions to fulfill different functions: the high ligand region ensures stable charge transport, while the low ligand region minimizes electrostatic capacity and charge retention at the electrode interface.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of organic ligand concentration across the thickness of the carrier transport layer. By controlling the gradient of ligand distribution (using different ratios of first and second ligands with varying lengths), the electrostatic capacity is reduced near the electrode while maintaining charge transport efficiency in the bulk of the layer.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If organic ligands are coordinated to carrier transport particles to stabilize the structure, then structural stability is improved, but electrical contact between particles and electrode deteriorates due to increased insulation

Engineering Contradiction:

Improvestructural stabilityVSAvoidelectrical contact quality

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent uses local quality by differentiating the ligand environment at different positions within the carrier transport layer. Near the photoelectric conversion layer, sufficient ligands provide structural stability, while near the electrode, reduced ligand concentration improves electrical contact without compromising overall structural integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining two different organic ligands (first ligand and second ligand) with different characteristics. The first ligand provides structural stability, while the second ligand (with shorter chain length) reduces insulation effects near the electrode, achieving a balance between stability and electrical contact through material composition optimization.

Inventive Principle:

Principle #40Composite materials

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 electrical contacts and reduces charge retention time in the electroluminescent element, improving performance.

Implementation Method 1

a carrier transport layer containing a plurality of carrier transport particles and a plurality of organic ligands capable of being coordinated to each of the plurality of carrier transport particles

Methodology Applied

Scientific EffectCoordination: Chemical Bonding

Implementation Method 2

Since the organic ligands are dielectric, defects could occur in electrical contacts between the nanoparticles and the electrode, which in turn would form an electrostatic capacity.

Methodology Applied

Scientific EffectElectrostatic capacity: Capacitance

Implementation Method 3

Since the organic ligands are dielectric, defects could occur in electrical contacts between the nanoparticles and the electrode

Methodology Applied

Scientific EffectDielectric: Dielectric

Data Source

PatentUS12414430B2Photoelectric conversion element, display device, and method of manufacturing photoelectric conversion element

Publication Date: 2025.09.09 SHARP KK

AI summary

A photoelectric conversion element includes: a first electrode and a second electrode; a photoelectric conversion layer between the first electrode and the second electrode; and a carrier transport layer between the photoelectric conversion layer and the second electrode, the carrier transport layer containing a plurality of carrier transport particles and a plurality of organic ligands, the carrier transport layer having a first end potion located close to the photoelectric conversion layer in a thickness direction of the carrier transport layer and a second end potion located close to the second electrode in the thickness direction of the carrier transport layer, wherein a first minimum distance between the plurality of carrier transport particles in the first end potion and the photoelectric conversion layer is larger than a second minimum distance between the plurality of carrier transport materials particles in the second end potion and the second electrode.