Zinc Oxide Transparent Conductor with Silver Grain Boundary Doping
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Solution Overview
Problem
Current zinc oxide transparent electric conductors have high resistivity compared to ITO, and attempts to reduce resistivity through doping or adding metals have been insufficient, often leading to deteriorated transmittance and mobility issues.
Innovation Solution
Selecting metals with favorable wettability to zinc oxide, such as cobalt, nickel, iron, or copper, and adding them in specific concentrations to the grain boundary of zinc oxide films to enhance mobility and reduce resistivity, while maintaining high transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zinc oxide is doped with n-type dopants (Ga, Al) to reduce resistivity, then electrical conductivity is improved, but resistivity remains significantly higher than ITO
Solution Approach 1:
The patent combines zinc oxide with n-type dopants (Ga or Al) and silver to create a composite transparent electric conductor. This composite structure allows the material to achieve low resistivity comparable to ITO by synergistically combining the properties of zinc oxide, dopants, and silver, rather than relying on dopants alone
Solution Approach 2:
The patent optimizes the concentration parameters of both the n-type dopant (Ga or Al) and silver to achieve optimal electrical conductivity. By precisely controlling the doping concentration and silver content, the resistivity is reduced to levels comparable to ITO while maintaining transparency
2Reliability
If metal is added to zinc oxide to reduce resistivity, then electrical conductivity is improved, but transmittance deteriorates
Solution Approach 1:
The patent precisely controls the concentration of silver and n-type dopants to optimize the balance between electrical conductivity and optical transparency. By adjusting these parameters within specific ranges, the material achieves low resistivity while maintaining high transmittance in the visible region
Solution Approach 2:
The patent introduces silver specifically at grain boundaries of the zinc oxide film, rather than uniformly distributing it throughout the bulk material. This localized addition improves electrical conductivity at critical interfaces while minimizing the overall metal content to preserve optical transparency
3Reliability
If conventional doping methods are used to reduce resistivity, then electrical conductivity is improved, but the resistivity reduction effect is insufficient compared to ITO
Solution Approach 1:
The patent creates a composite structure of zinc oxide with n-type dopants and silver, which provides superior resistivity control compared to conventional single-dopant methods. The combination allows for more precise tuning of electrical properties to match or exceed ITO performance
Solution Approach 2:
The patent employs dual-parameter optimization by simultaneously controlling the concentration of n-type dopants (Ga or Al) and silver content. This multi-parameter approach enables precise control over resistivity, achieving values comparable to ITO that cannot be obtained with single-dopant methods
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 approach results in a zinc oxide transparent electric conductor with resistivity comparable to ITO, avoiding the use of expensive and scarce indium, and achieving improved electrical conductivity without compromising transmittance.
Implementation Method 1
a sputtering target for forming a zinc oxide transparent electric conductor
Implementation Method 2
containing metal M in which P (P=(ΔG0+ΔHx(M))/RT, wherein ΔG0 is a standard free energy change of redox reaction of metal M and zinc oxide, ΔHx(M) is a heat of dissolution of zinc as a constituent metal element of zinc oxide to metal M, R is a gas constant, and T is a temperature) as a parameter showing the wettability with zinc oxide
Implementation Method 3
containing an element to become an n-type dopant to zinc oxide
Data Source
AI summary
Provided is a zinc oxide transparent electric conductor having zinc oxide (ZnO) as its principal component, containing an element to become an n-type dopant to zinc oxide, containing metal M in which P(P=(G+H mix)/RT, wherein G is the Gibbs free energy at temperature T of the metal, H mix is the mixing enthalpy at temperature T of zinc oxide and the metal, R is the gas constant, and T is the temperature) as a parameter showing the wettability with zinc oxide is 6 or less and in which its resistivity is smaller than the resistivity of zinc oxide added with the n-type dopant, and wherein concentration of metal M in relation to the total atomicity of zinc and the n-type dopant and metal M, which are all metal atoms configuring the zinc oxide transparent electric conductor, is 0.05 to 2.0 at %. In the development of a transparent electric conductor that does not contain raw material In which is expensive and with concern of resource depletion, provided is a low resistivity transparent electric conductor by exceeding the limits of the conventional development technique of the single dopant method, presenting guidelines for selecting a secondary additive material effective in achieving low resistivity, and indicating types of specific materials and the appropriate concentration range.