Plasmonic Nanostructures for Optical-to-Electrical Power Conversion

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Solution Overview

Problem

Existing methods for converting optical power to electrical power using plasmonic nanostructures suffer from low efficiency due to the short excited state lifetime of electrons in metals, which limits the ability to harness high energy density effectively.

Innovation Solution

The plasmoelectric effect is utilized, where charge transport is induced by changes in internal charge density of plasmonic nanostructures through off-resonant irradiation, eliminating the need for semiconductor or insulating components and allowing for efficient conversion of optical power to direct current (DC) electrical power using an all-metal circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If resonant optical absorption is used in plasmonic nanostructures to generate high internal energy density, then the energy density is improved, but the optical-to-electrical power conversion efficiency deteriorates due to short excited state lifetime

Engineering Contradiction:

Improveinternal energy densityVSAvoidoptical-to-electrical power conversion efficiency

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent changes the irradiation parameter from resonant frequency to off-resonant frequency to alter the excitation mechanism. This parameter change extends the excited state lifetime of electrons while still generating sufficient charge separation to drive current through the circuit, thereby resolving the contradiction between energy density and conversion efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic control of charge transport by applying external bias voltage to the plasmonic nanostructure. This dynamic control allows optimization of electron extraction timing and efficiency, enabling better utilization of the extended excited state lifetime to improve power conversion efficiency while maintaining energy density

Inventive Principle:

Principle #15Dynamics

2Reliability

If semiconductor or insulating components are used to rectify excited electrons, then the conversion mechanism is established, but the interface barrier height and transit time cannot be optimized due to fast electronic relaxation

Engineering Contradiction:

Improveconversion mechanismVSAvoidinterface optimization

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the semiconductor or insulating interface components from the system. By using only plasmonic metal nanostructures with off-resonant irradiation, the patent removes the interface barrier problem entirely while maintaining the charge separation and rectification functions through the plasmonic effect alone, thereby achieving both reliability and ease of manufacture

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an external bias voltage as an intermediary control mechanism to replace the need for semiconductor interfaces. This voltage mediator enables optimization of electron transport and rectification without requiring physical interface barriers, solving the contradiction between reliable conversion and ease of manufacture

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 approach significantly enhances the optical-to-electrical power conversion efficiency by maximizing plasmoelectric potential differences and currents, overcoming the limitations of short electron lifetimes and resonant absorption inefficiencies.

Implementation Method 1

When incident light (e.g., from a light beam) interacts with a plasmonic material, stimulated valence electrons on the surface of the material (sometimes referred to as plasmons or surface plasmons) collectively ripple to create electromagnetic waves on the boundary between the surface of the material and the surrounding medium

Methodology Applied

Scientific EffectPlasmon resonance: Resonance

Implementation Method 2

Plasmonic nanostructures exhibit high internal energy density when irradiated with light. This high internal energy density arises from the coupling of their resonant free electron oscillations to the incident light

Methodology Applied

Scientific EffectResonant optical absorption: Absorption (EM radiation)

Implementation Method 3

charge transport can be induced solely by changes in their internal charge density. This distinctive behavior is described herein as the 'plasmoelectric effect.' The plasmoelectric effect induces 'plasmoelectric potentials' in the nanostructures

Methodology Applied

Scientific EffectPlasmoelectric effect:

Data Source

PatentUS10075104B2Plasmonic nanostructures for conversion of optical power to electrical power

Publication Date: 2018.09.11 CALIFORNIA INST OF TECH

AI summary

A plasmoelectric device for conversion of optical power to direct current (DC) electrical power includes a first plasmonic nanostructure having a first resonance value and a second plasmonic nanostructure having a second resonance value. The first and second plasmonic nanostructures are electrically coupled and the first plasmonic nanostructure is configured to receive irradiation at a first irradiation value and the second plasmonic nanostructure is configured to receive irradiation at a second irradiation value, to induce charge transfer between the first and second plasmonic nanostructures.