Multilayer Transparent Electrode for Visible and Infrared Transmission
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Solution Overview
Problem
Existing transparent electrical conductors are only transparent in the visible spectrum and highly reflective in the infrared spectral region, lacking transparency and conductivity in both visible and infrared regions.
Innovation Solution
A multilayer thin film structure comprising an adhesion-enhancing optical-matching layer, a metallic conduction layer, and an overcoat layer, with specific thicknesses and materials such as silicon and silver, deposited on a substrate to achieve high transparency and low sheet resistance across the visible and infrared spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thicker metallic layers are used to reduce sheet resistance, then electrical conductivity improves, but optical transparency deteriorates due to increased reflectivity and absorption
Solution Approach 1:
The patent divides the total metallic thickness into multiple thin sequential layers (e.g., several 5-15 nm silver layers instead of one 50 nm layer). This segmentation maintains the total conductive path length needed for low sheet resistance while ensuring each individual layer remains thin enough to allow light transmission, preventing the increased reflectivity and absorption that would occur with a single thick layer.
Solution Approach 2:
The patent transitions from a single-dimensional thick layer approach to a multi-dimensional layered structure, utilizing the vertical dimension to stack multiple thin layers. This dimensional change allows the system to achieve the electrical conductivity of a thick layer while maintaining the optical transparency of thin layers, as light passes through multiple thin interfaces rather than one thick interface.
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 provides a thin film with greater than 50% optical transparency and sheet resistance values between 3 and 100 Ohms/sq, suitable for both visible and infrared applications, with excellent flexibility and environmental durability.
Implementation Method 1
an adhesion-enhancing, optical-matching layer deposited directly on the substrate... The adhesion-enhancing optical-matching layer may substantially reduce substrate/silicon interface reflection
Implementation Method 2
a metallic conduction layer deposited on the adhesion-enhancing, optical-matching layer and comprises silver, gold, copper or aluminum
Implementation Method 3
High electrical conductance requires minimal electron scattering loss at the interfaces of conductive film. Therefore, electron scattering must be minimized through implementation of non-scattering interfaces
Implementation Method 4
An overcoat layer deposited on this metallic conduction layer preferably comprises silicon
Data Source
AI summary
An electrically conductive multilayer thin film structure and composition is transparent in both the visible and infrared portions of the spectrum. This multilayer film is readily deposited on a variety of substrates, including plastics, and survives such in service conditions as flexing, vibration, thermal cycling, thermal shock, ultraviolet exposure, and high humidity. The preferred films are also compatible with conventional photolithography processes.