Organic Photoelectronic Device with Charge Buffer Layers

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Solution Overview

Problem

Silicon photodiodes used in image sensors have limited sensitivity due to their small absorption area, necessitating the development of alternative materials that can enhance photoelectric conversion efficiency and wavelength selectivity.

Innovation Solution

An organic photoelectronic device is designed with an organic layer containing a specific visible light-absorbing compound and charge buffer materials, which includes a hole buffer material and an electron buffer material, optimized to absorb light in the green wavelength region with high selectivity, thereby improving sensitivity and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If silicon photodiode is used to achieve high resolution, then pixel size can be reduced, but sensitivity deteriorates due to small absorption area

Engineering Contradiction:
ImproveresolutionVSAvoidsensitivity
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent changes the material parameter from silicon to organic compound, which fundamentally alters the absorption characteristics. The organic compound has higher extinction coefficient and can be tuned to absorb specific wavelengths, thereby improving sensitivity without requiring larger pixel area, thus resolving the contradiction between high resolution and sensitivity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material structure combining organic compound with charge buffer materials (hole buffer and electron buffer). This composite approach enhances the photoelectric conversion efficiency by separating and transporting charges effectively, thereby improving sensitivity while maintaining small pixel size for high resolution

Inventive Principle:
Principle #40Composite materials

2Reliability

If organic material is used to replace silicon, then sensitivity and integration are improved, but photoelectric conversion efficiency and wavelength selectivity need to be optimized

Engineering Contradiction:
ImprovesensitivityVSAvoidphotoelectric conversion efficiency
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The patent applies local quality by introducing charge buffer materials with specific properties at strategic locations within the organic photoelectronic device. The hole buffer material and electron buffer material are positioned to facilitate charge separation and transport, thereby optimizing photoelectric conversion efficiency in specific regions of the device

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent optimizes wavelength selectivity by selecting organic compounds with specific molecular structures that absorb in the green wavelength region. By tuning the molecular structure and energy levels of the organic material and buffer materials, the device achieves high photoelectric conversion efficiency at specific wavelengths

Inventive Principle:
Principle #35Parameter changes

3Power

If organic layer with charge buffer materials is used to improve photoelectric conversion efficiency, then device complexity increases

Engineering Contradiction:
Improvephotoelectric conversion efficiencyVSAvoidstructure complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into the organic layer structure. The organic layer simultaneously serves as the light-absorbing active layer and incorporates charge buffer materials for hole and electron transport. This integration reduces the need for separate buffer layers, thereby improving photoelectric conversion efficiency while minimizing device complexity

Inventive Principle:
Principle #5Merging (Combining)

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 organic photoelectronic device achieves high photoelectric conversion efficiency and wavelength selectivity, enabling the development of advanced image sensors with improved sensitivity and reduced crosstalk by selectively absorbing light in specific wavelength regions.

Implementation Method 1

The organic photoelectronic device converts light into an electrical signal using photoelectronic effects

Methodology Applied
Scientific EffectPhotoelectric conversion: Photovoltaic Effect

Implementation Method 2

The organic layer including a compound represented by the following Chemical Formula 1 as a visible light-absorbing body

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP2927981B1Organic photoelectronic device and image sensor
Publication Date: 2021.03.10 SAMSUNG ELECTRONICS CO LTD
  • EP2927981B1 patent drawingFigure 1~2
  • EP2927981B1 patent drawingFigure 3~4
  • EP2927981B1 patent drawingFigure 5

AI summary

An organic photoelectronic device includes an anode and a cathode facing each other, and an organic layer between the anode and the cathode, the organic layer including a compound represented by Chemical Formula 1 as a visible light-absorbing body, and at least one of a hole buffer material having an energy bandgap of greater than or equal to about 2.8 eV and a HOMO level between a work function of the anode and a HOMO level of the compound represented by the Chemical Formula 1, and an electron buffer material having an energy bandgap of greater than or equal to about 2.8 eV and a LUMO level between a work function of the cathode and a LUMO level of the compound represented by the Chemical Formula 1.