Sputtering Target with Dispersed Sodium Compounds for CIGS Solar Cells
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Solution Overview
Problem
Sputtering targets containing sodium compounds like sodium sulfate, sodium sulfite, sodium selenate, and sodium selenite suffer from discoloration, moisture absorption, and abnormal discharge issues, leading to unstable solar battery characteristics and mechanical weakness.
Innovation Solution
A sputtering target with a composition of Ga 10-40 at.% and Na 0.1-15 at.%, where Na is in the form of sodium sulfate, sulfite, selenate, or selenite, with a dispersed Na compound phase and average grain size ≤10 μm, and a production method involving mixed powder sintering in a non-oxidizing atmosphere to achieve high density and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sodium compounds (sodium sulfate, sodium sulfite, sodium selenate, sodium selenite) are added to the sputtering target to improve power generation efficiency, then the power generation efficiency of the solar battery is improved, but discoloration and abnormal discharge occur during sputtering
Solution Approach 1:
The patent changes the chemical form of sodium from conventional compounds to specific compounds (sodium sulfate, sodium sulfite, sodium selenate, or sodium selenite) and controls the grain size parameter (average grain size of 10 μm or less) to suppress abnormal discharge and discoloration while maintaining power generation efficiency improvement
Solution Approach 2:
The patent creates a composite sputtering target material combining copper, gallium, and specific sodium compounds with controlled grain structure, achieving both the beneficial effect of improved power generation efficiency and the suppression of harmful effects through proper material composition and structure
2Reliability
If sodium compounds are added to the sputtering target to improve power generation efficiency, then the power generation efficiency is improved, but the mechanical strength of the sputtering target is reduced
Solution Approach 1:
The patent controls the grain size parameter (average grain size of 10 μm or less) and the form of sodium compounds to maintain mechanical strength while allowing sufficient sodium content (0.1-15 at.%) to be incorporated for improving power generation efficiency
Solution Approach 2:
The patent develops a composite material system where copper, gallium, and specific sodium compounds are combined in a controlled microstructure, achieving both improved power generation efficiency and adequate mechanical strength through proper composition and grain size control
3Object-generated harmful factors
If the grain size of Na compound phase is reduced to suppress abnormal discharge, then abnormal discharge is suppressed, but the production process becomes more complex
Solution Approach 1:
The patent specifies a quantitative grain size parameter (average grain size of 10 μm or less) that can be controlled through standard sintering processes, suppressing abnormal discharge without requiring excessively complex production procedures
Solution Approach 2:
The patent applies local quality control by specifying the grain size of the sodium compound phase specifically, allowing the rest of the sputtering target to be produced using conventional methods, thus minimizing production process complexity while achieving the desired suppression of abnormal discharge
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 suppresses discoloration and abnormal discharge while maintaining high mechanical strength and conductivity, enabling efficient deposition of CIGS thin-film solar batteries with improved power generation efficiency and productivity.
Implementation Method 1
a sputtering method for forming a light absorbing layer has been proposed
Implementation Method 2
producing a sintered body by sintering the mixed powder
Data Source
AI summary
A sputtering target consists of a sintered body having a component composition consisting of: Ga of 10 to 40 at. % and Na of 0.1 to 15 at. % as metal elements; and the balance being Cu and inevitable impurities. The sintered body contains the Na in a form of Na compounds consisting of at least one compound selected from the group consisting of sodium sulfate, sodium sulfite, sodium selenate, and sodium selenite, the sintered body has a composition in which a Na compound phase is dispersed, and an average grain size of the Na compound phase is 10 μm or less.