ZnTe:Cu Back Contacts With Hydrogen-Balanced Transmissivity
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Solution Overview
Problem
Existing research on the effects of hydrogen gas during sputtering of copper-doped zinc telluride thin films for solar cells is limited and inconclusive, particularly in the context of transmissive solar cells, leading to unfavorable changes in electrical properties and a lack of optimization methods for achieving commercially viable photoelectric performance.
Innovation Solution
A method for manufacturing transmissive solar cells involving the use of hydrogen gas in a controlled concentration within a vacuum chamber during the deposition of copper-doped zinc telluride back contacts, balancing optical and electrical properties by adjusting deposition parameters such as temperature and gas mix to enhance both properties simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If hydrogen gas is added to the argon gas during sputtering of copper-doped zinc telluride thin films, then film transmissivity increases due to increased bandgap, but film resistivity increases to an extent that it becomes unmeasurable
Solution Approach 1:
The patent applies parameter changes by precisely controlling the hydrogen gas concentration (0.01% to 0.10%) and deposition temperature (200°C to 600°C) to achieve optimal balance between transmissivity and resistivity. This resolves the contradiction by finding specific parameter values where both optical and electrical properties are improved simultaneously, contrary to previous findings that showed only transmissivity improvement with resistivity deterioration.
Solution Approach 2:
The patent applies local quality by creating different property zones within the deposited film through controlled hydrogen incorporation. The hydrogen concentration and temperature parameters create localized variations in the film structure that simultaneously enhance optical transmissivity in certain regions while maintaining electrical conductivity in other regions, resolving the contradiction between these two properties.
2Manufacturing precision
If conventional sputtering techniques are used to create thin films, then extremely fine uniform layers are achieved, but the electrical properties deteriorate when hydrogen gas is present
Solution Approach 1:
The patent applies preliminary action by pre-calibrating the deposition temperature and pre-controlling the hydrogen gas concentration before the actual deposition process. This preliminary setup ensures that when hydrogen is present during sputtering, the film maintains both uniformity and good electrical properties, resolving the contradiction between manufacturing precision and electrical reliability.
Solution Approach 2:
The patent applies feedback by monitoring and adjusting deposition parameters based on real-time measurements of film properties. This feedback mechanism allows the process to maintain optimal balance between film uniformity and electrical properties even in the presence of hydrogen gas, resolving the technical contradiction.
3Illumination intensity
If the focus is on optimizing optical properties of transmissive solar cells, then transmissivity is improved, but electrical properties and power conversion efficiency are compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the combination of hydrogen gas concentration (0.01% to 0.10%) and deposition temperature (200°C to 600°C) to achieve a sweet spot where both optical transmissivity and electrical properties are improved. This resolves the contradiction by demonstrating that proper parameter control can simultaneously enhance both transmissivity and power conversion efficiency to achieve 10% or greater efficiency.
Solution Approach 2:
The patent applies composite materials by creating a copper-doped zinc telluride (Cu-doped ZnTe) back contact layer with controlled hydrogen incorporation. This composite structure combines the benefits of high transmissivity from hydrogen-induced bandgap increase with good electrical conductivity from controlled doping and deposition conditions, resolving the contradiction between optical and electrical performance for achieving 10%+ power conversion efficiency.
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 method results in a transmissive solar cell with improved electrical and optical performance, achieving a power conversion efficiency of 10% or greater, balancing composition, thickness, and transmissivity to provide commercially viable photoelectric performance.
Implementation Method 1
Sputtering, generally, is an atomic/microscopic deposition of particles of a target material onto a surface of a substrate within a vacuum chamber containing a gas, such as argon gas (Ar).
Implementation Method 2
heating a surface of a partially manufactured cadmium (Cd) alloy transmissive solar cell within the vacuum chamber to a calibrated deposition temperature
Data Source
AI summary
A method of manufacturing a cadmium (Cd) alloy transmissive solar cell is provided. The method includes pumping a vacuum chamber to a base pressure and pumping the vacuum chamber to a sputtering pressure. The method includes providing into the vacuum chamber a first gas at a rate that balances a flow of the first gas in and out of the vacuum chamber with respect to the sputtering pressure and heating a surface of a partially manufactured cadmium (Cd) alloy transmissive solar cell within the vacuum chamber to a calibrated deposition temperature. The method includes providing into the vacuum chamber a second gas including at least a hydrogen gas (H2) at a proportional rate to achieve a target gas mix while maintaining the sputtering pressure and depositing a target material onto the surface to form a back contact section of the cadmium (Cd) alloy transmissive solar cell.