Roll-to-roll CIGS Solar Cell Sputtering with Zirconium Nitride Barrier
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Solution Overview
Problem
Current methods for manufacturing thin-film solar cells, particularly those using copper indium gallium diselenide (CIGS) materials, face challenges in scalability, high production costs, and the use of toxic materials like cadmium, which hinder large-scale production and efficiency.
Innovation Solution
A roll-to-roll deposition system using dual cylindrical rotary magnetrons for DC sputtering of the CIGS absorber layer and RF sputtering of the ZnS buffer layer, eliminating cadmium and incorporating a zirconium nitride barrier layer to improve reflectivity and conductivity, while also using aluminum doped ZnO for the transparent electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sputtering methods are used for CIGS deposition, then manufacturing process is simpler, but manufacturing precision and material stability are insufficient
Solution Approach 1:
The absorber layer deposition is divided into two separate sputtering steps: first depositing a metal layer (Cu-In-Ga alloy) and then depositing a selenium layer. This segmentation allows independent optimization of each layer's composition and structure, achieving precise control over the final CIGS absorber layer stoichiometry and crystal structure, which resolves the contradiction between manufacturing precision and process simplicity.
Solution Approach 2:
The metal layer is deposited first as a preliminary step before selenium deposition. This preliminary action creates a structured substrate that guides the subsequent selenium incorporation, ensuring proper atomic arrangement and preventing material instability. The pre-formed metal layer acts as a template that enhances the overall manufacturing precision of the absorber layer.
2Productivity
If roll-to-roll processing is implemented, then productivity increases, but manufacturing precision of thin films decreases
Solution Approach 1:
The invention implements continuous roll-to-roll sputtering processing where the substrate continuously moves through the deposition chamber while maintaining steady-state deposition conditions. This continuity enables high productivity while the controlled sputtering parameters (power, gas flow, substrate temperature) ensure uniform film thickness and composition, resolving the contradiction between production throughput and film quality.
Solution Approach 2:
The sputtering process parameters are optimized for roll-to-roll operation, including adjusting deposition rate, substrate temperature, and gas pressure to maintain film quality during continuous processing. By carefully controlling these parameters, the system achieves both high productivity and manufacturing precision, with uniform absorber layers deposited at industrial-scale speeds.
3Ease of manufacture
If cadmium-based materials are used, then manufacturing cost is reduced, but harmful factors increase due to toxicity
Solution Approach 1:
The invention replaces toxic cadmium-based materials with non-toxic CIGS (copper indium gallium selenide) materials while maintaining or improving cell efficiency. This substitution eliminates the harmful factors associated with cadmium handling and disposal, and the two-step sputtering process ensures high-quality CIGS absorber layers that achieve competitive conversion efficiencies, thus converting a harmful manufacturing approach into a beneficial one.
Solution Approach 2:
The absorber layer is formed as a composite CIGS material combining copper, indium, gallium, and selenium in specific ratios. This composite material structure provides both environmental benefits (no cadmium) and performance benefits (tunable bandgap, high efficiency), while the two-step sputtering process enables precise compositional control to optimize both cost and environmental compatibility.
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 enables large-scale, cost-effective production of thin-film solar cells with improved efficiency by reducing toxic material usage, enhancing reflectivity, and increasing substrate size capabilities, making solar power more competitive with conventional energy sources.
Implementation Method 1
A method of manufacturing a solar cell is disclosed which uses a roll-to-roll processing technique with a vacuum deposition system to deposit layers of material onto a moving substrate. The absorber layer is formed by evaporation of copper, indium, gallium, and selenium materials in defined stoichiometric ratios.
Implementation Method 2
Several of the layers are formed by evaporation of the desired material in vacuum chambers.
Data Source
AI summary
A method of manufacturing improved thin-film solar cells entirely by sputtering includes a high efficiency back contact/reflecting multi-layer containing at least one barrier layer consisting of a transition metal nitride. A copper indium gallium diselenide (Cu(InxGa1-x)Se2) absorber layer (X ranging from 1 to approximately 0.7) is co-sputtered from specially prepared electrically conductive targets using dual cylindrical rotary magnetron technology. The band gap of the absorber layer can be graded by varying the gallium content, and by replacing the gallium partially or totally with aluminum. Alternately the absorber layer is reactively sputtered from metal alloy targets in the presence of hydrogen selenide gas. RF sputtering is used to deposit a non-cadmium containing window layer of ZnS. The top transparent electrode is reactively sputtered aluminum doped ZnO. A unique modular vacuum roll-to-roll sputtering machine is described. The machine is adapted to incorporate dual cylindrical rotary magnetron technology to manufacture the improved solar cell material in a single pass.