Cuprous Oxide Solar Cell Sputtering for Low-Phase Recombination
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Solution Overview
Problem
Current methods for manufacturing cuprous oxide solar cells face challenges such as low efficiency due to incomplete removal of heterogeneous phases and impurities, which affect the formation of a favorable pn junction and reduce the solar cell's ability to absorb light effectively.
Innovation Solution
The solar cell design includes a photoelectric conversion layer made of cuprous oxide, formed using a sputtering method with controlled oxygen and argon gas ratios to minimize heterogeneous phases, and a specific structure with a first electrode, n-type layer, and second electrode to enhance light absorption and conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a copper foil is oxidized and etched to form a cuprous oxide solar cell, then the solar cell can be manufactured with a wide band gap material, but heterogeneous phases and impurities remain that prevent favorable pn junction formation
Solution Approach 1:
The patent extracts and removes heterogeneous phases (copper, copper oxide) and impurities from the photoelectric conversion layer through controlled etching processes. The etching solution selectively removes unwanted phases while preserving the cuprous oxide structure, enabling favorable pn junction formation by extracting harmful components that prevent reliable junction operation.
Solution Approach 2:
The patent changes the chemical parameters of the etching solution (composition, concentration, temperature) to optimize the removal of heterogeneous phases. By adjusting these parameters, the etching process achieves complete removal of copper and copper oxide phases while maintaining the integrity of the cuprous oxide photoelectric conversion layer, thereby improving pn junction quality.
2Ease of manufacture
If a thin film is formed by liquid phase reaction method, then the manufacturing process is simple, but impurities are incorporated into the film that serve as recombination centers
Solution Approach 1:
The patent replaces the liquid phase chemical reaction method with a physical vapor deposition or solution-based deposition method followed by controlled oxidation. This substitution eliminates the incorporation of solution impurities into the film structure, as the new method uses vapor-phase or controlled liquid-phase deposition without the harmful impurities present in conventional liquid phase reaction solutions, thereby preventing recombination centers.
3Manufacturing precision
If a thin film is manufactured by sputtering method, then the film has small amount of contaminated impurities, but heterogeneous phases of copper or copper oxide are easily generated
Solution Approach 1:
The patent changes the sputtering parameters (gas composition, power, temperature, oxygen partial pressure) to control the formation of heterogeneous phases. By optimizing these parameters, the sputtering process produces a photoelectric conversion layer with minimal heterogeneous phases while maintaining low impurity content, achieving both high manufacturing precision and reliability.
Solution Approach 2:
The patent performs preliminary oxidation of the copper-containing layer during or immediately after the sputtering process, before heterogeneous phases can form. This preliminary action converts the copper material into cuprous oxide in a controlled manner, preventing the subsequent formation of unwanted heterogeneous phases while maintaining the benefits of low impurity content from the sputtering method.
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 results in a higher conversion efficiency by reducing the number of heterogeneous phases, preventing recombination of photoexcited carriers, and improving the quality of the photoelectric conversion layer, thereby enhancing the overall solar cell performance.
Implementation Method 1
a photoelectric conversion layer which is a p-type compound semiconductor layer containing cuprous oxide
Implementation Method 2
a film of the cuprous oxide compound is formed by heating at 450° C. by a sputtering method
Data Source
AI summary
According to one embodiment, a solar cell includes a first electrode, a second electrode, and a photoelectric conversion layer disposed between the first electrode and the second electrode. In a case where a photoluminescence spectrum of the photoelectric conversion layer is measured at a temperature of 100 K or lower, a first maximum value (A) which is a maximum value of emission intensity in a wavelength range of more than 650 nm and 1000 nm or less is 100 times or less of a second maximum value (B) which is a maximum value of emission intensity in a wavelength range of 600 nm or more and 650 nm or less (A≤100B).