Cu-Ga-In-Na Sputtering Target for CIGS Solar Cells
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Solution Overview
Problem
Sputtering targets for CIGS-based solar cells produced using alkali metal salts or organic compounds suffer from contamination, reduced homogeneity, and material losses, leading to inhomogeneities and corrosion issues, which affect the quality and efficiency of the deposited layers.
Innovation Solution
A sputtering target composed of a Cu—Ga—Na, Cu—In—Na, or Cu—Ga—In—Na alloy with intermetallic Na-containing phases is developed, eliminating the need for organic compounds or salts, ensuring high purity, homogeneous microstructure, and improved handling, by incorporating intermetallic phases like NaGa4, Na5Ga8, and Na17Ga29In12, which provide strong bonds and stable Na distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alkali metal salts or organic compounds are introduced into the target, then Na content is increased to improve efficiency, but contamination and inhomogeneity occur
Solution Approach 1:
The patent changes the chemical form of Na from salts/organic compounds to intermetallic phases, fundamentally altering the parameter of Na's chemical state. This transformation eliminates contamination while maintaining Na content, resolving the contradiction between quantity and homogeneity.
Solution Approach 2:
The patent uses intermetallic phases (composite structures of Na with Ga or In) as the Na carrier instead of simple salts or organic compounds. These composite materials provide stable Na distribution without contamination, simultaneously achieving high Na content and homogeneity.
2Quantity of substance
If alkali metal salts are used, then Na is introduced to increase p-type conductivity, but chemical stability decreases leading to material losses
Solution Approach 1:
The patent transforms Na from a chemically unstable salt form to a stable intermetallic phase form. This parameter change in chemical state dramatically improves reliability and chemical stability while preserving the desired Na content for conductivity enhancement.
Solution Approach 2:
The patent replaces unstable, short-lived Na salts that decompose and cause material losses with stable, long-lasting intermetallic phases. The intermetallic phases maintain Na content without decomposition, eliminating material losses and improving reliability.
3Quantity of substance
If organic compounds are used as Na carrier, then Na is introduced to improve efficiency, but contamination by organic constituents occurs
Solution Approach 1:
The patent changes the chemical parameter of Na from organic compound form to intermetallic phase form. This transformation completely eliminates organic contamination while maintaining Na content, resolving the contradiction between quantity and purity.
Solution Approach 2:
The patent extracts and removes the harmful organic constituents from the Na carrier system, retaining only the beneficial Na element in a clean intermetallic phase form. This extraction eliminates contamination while preserving the desired Na content.
4Quantity of substance
If salts are introduced to increase Na content, then efficiency is improved, but hygroscopic properties cause corrosion
Solution Approach 1:
The patent changes the chemical state of Na from hygroscopic salts to non-hygroscopic intermetallic phases. This parameter change eliminates the harmful hygroscopic property that causes corrosion, while maintaining the beneficial Na content for efficiency improvement.
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 intermetallic phase-based sputtering target achieves enhanced purity, stability, and homogeneity, reducing material losses and corrosion, resulting in improved sputtering results and increased efficiency of thin-film solar cells with optimized Na distribution and microstructure.
Implementation Method 1
Photoactive layers for thin-film solar cells are produced via physical vapour deposition (PVD) processes. These are coating processes in which the layer formation takes place through vaporization of the layer-forming particles from a target and the condensation of this vapour on the substrate to be coated.
Data Source
AI summary
A sputtering target is composed of an alloy consisting of 5 to 70 at % of at least one element from the group of (Ga, In) and 0.1 to 15 at % of Na, the remainder being Cu and typical impurities. The sputtering target includes at least one intermetallic Na-containing phase.