Singlet Fission Image Sensor Structure for Small-Pixel Sensitivity

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Solution Overview

Problem

The challenge is to enhance the resolution and sensitivity of image sensors while maintaining high integration, as the smaller pixel size limits the absorption area of silicon, thereby reducing sensitivity.

Innovation Solution

The proposed solution involves an image sensor design that includes a semiconductor substrate with photodiodes, a color filter layer, an organic intermediate layer containing a singlet fission material, and an inorganic intermediate layer. The organic intermediate layer has an extinction coefficient greater than or equal to 1×10^4 cm^-1 and a singlet fission efficiency greater than 50%, which enhances photoelectric conversion efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the pixel size is reduced to increase integration, then the resolution and integration are improved, but the absorption area of silicon is reduced, which deteriorates the sensitivity

Engineering Contradiction:

ImproveintegrationVSAvoidsensitivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces an organic intermediate layer with singlet fission material between the inorganic photodiode and color filter layer. This composite structure combines inorganic photodiodes with organic materials that have complementary light absorption characteristics, enabling the organic layer to absorb photons in regions where silicon has low absorption efficiency and generate excitons that can be transferred to the photodiode, thereby maintaining high sensitivity even with reduced pixel size

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the optical parameters of the pixel structure by introducing materials with specific optical properties - the organic intermediate layer has high absorption coefficient and singlet fission efficiency, allowing it to absorb a broader spectrum of light including wavelengths where silicon absorption is weak, thus compensating for the reduced absorption area in smaller pixels

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the pixel size is reduced to increase integration, then the integration is improved, but the photoelectric conversion efficiency is reduced, which deteriorates the sensitivity

Engineering Contradiction:

ImproveintegrationVSAvoidphotoelectric conversion efficiency

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The organic intermediate layer acts as a composite material that enhances photoelectric conversion by absorbing photons and generating excitons through singlet fission, which can then be transferred to the inorganic photodiode. This composite approach enables efficient photoelectric conversion even when the inorganic photodiode area is reduced due to higher integration

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The organic intermediate layer serves as an intermediary between the incident light and the inorganic photodiode. It absorbs photons that would otherwise pass through or be poorly absorbed by the reduced-size photodiode, converts them to excitons via singlet fission, and transfers these excitons to the photodiode, thereby maintaining high photoelectric conversion efficiency in highly integrated structures

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design achieves high external quantum efficiency, exceeding that of inorganic photodiodes, thereby improving the sensitivity and integration capabilities of the image sensor.

Implementation Method 1

an organic intermediate layer between the semiconductor substrate and the color filter layer and including a singlet fission material

Methodology Applied

Scientific EffectSinglet fission:

Implementation Method 2

an organic intermediate layer including an organic material configured to absorb light transmitted through the color filter layer, to convert the absorbed light into photoelectricity

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 3

an inorganic intermediate layer between the organic intermediate layer and the inorganic photodiode and including at least one of an oxide, nitride, oxynitride, fluoride or oxyfluoride including a metal or a semi-metal

Methodology Applied

Scientific EffectCharge transfer:

Implementation Method 4

a color filter layer on the semiconductor substrate and including a plurality of color filters arranged along an in-plane direction of the semiconductor substrate

Methodology Applied

Scientific EffectSelective light transmission: Absorption (EM radiation)

Data Source

PatentUS20250185395A1Image sensor and electronic device

Publication Date: 2025.06.05 SAMSUNG ELECTRONICS CO LTD

AI summary

An image sensor includes a semiconductor substrate including a plurality of photodiodes, a color filter layer on the semiconductor substrate and including a plurality of color filters arranged along an in-plane direction of the semiconductor substrate, and an organic intermediate layer between the semiconductor substrate and the color filter layer and including a singlet fission material. An extinction coefficient of the organic intermediate layer at a maximum absorption wavelength is greater than or equal to 1×104 cm−1, and a singlet fission efficiency of the organic intermediate layer is greater than 50%.