Cu2O Multilayer Thin Film Processing for Higher Solar Cell Efficiency
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Solution Overview
Problem
Current methods for manufacturing cuprous oxide solar cells, such as those using copper foil oxidation, face challenges in achieving high efficiency due to incomplete removal of heterogenous phases, which hinders the formation of a favorable p-n junction and limits the area of the solar cells, and existing sputtering processes do not adequately improve conversion efficiency.
Innovation Solution
A process involving the deposition of a Cu2O photovoltaic conversion layer on a transparent electrode under controlled low-oxygen atmospheres, followed by retention in a low-oxygen environment to form a CuO-containing region, resulting in a multilayered thin film with enhanced crystallinity and light transmissivity, thereby improving solar cell efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If copper foil is oxidized and heterogenous phase is removed by etching, then cuprous oxide thin film can be formed, but it is impossible to remove the phase completely and constituent elements in the etching solution remain, resulting in lower conversion efficiency
Solution Approach 1:
The patent extracts and removes heterogenous phases (CuO, Cu) from the cuprous oxide thin film through a multi-step process: first etching with FeCl3 solution to remove surface heterogenous phases, then performing selective oxidation to convert remaining Cu to CuO, and finally removing CuO with dilute HCl solution. This sequential extraction process achieves complete removal of heterogenous phases without leaving etching solution residues, thereby improving both manufacturing precision and conversion efficiency
Solution Approach 2:
The patent applies preliminary action by performing initial etching with FeCl3 solution before the main oxidation process. This preliminary etching step removes surface heterogenous phases and prepares the surface for subsequent selective oxidation, ensuring that the main oxidation process can proceed efficiently and achieve complete purification without residue contamination
2Manufacturing precision
If copper foil with thickness of about 0.1 mm is oxidized and then polished to about 20 μm, then cuprous oxide thin film can be obtained, but it is difficult to make the area large
Solution Approach 1:
The patent replaces the mechanical polishing process with a chemical etching process using FeCl3 solution. This substitution allows for area expansion because chemical etching can be uniformly applied to large surfaces without the mechanical constraints of polishing equipment. The etching process maintains precise thickness control through controlled chemical reactions while enabling manufacturing of large-area solar cells
Solution Approach 2:
The patent changes the processing parameters by using chemical etching instead of mechanical polishing, and by controlling the etching time and solution concentration to achieve the desired thickness of about 20 μm. This parameter change enables scalable production of large-area solar cells while maintaining precise thickness control through measurable and controllable chemical processes
3Ease of manufacture
If sputtering is used to manufacture cuprous oxide thin film, then a thin film can be formed, but the conversion efficiency should be improved further
Solution Approach 1:
The patent employs a composite manufacturing approach that combines sputtering (to form the initial cuprous oxide thin film) with chemical etching (using FeCl3 solution to remove heterogenous phases) and selective oxidation (to convert Cu to CuO for subsequent removal). This composite process leverages the ease of manufacture of sputtering while adding subsequent steps that significantly improve conversion efficiency by achieving complete purification of the thin film
Solution Approach 2:
The patent changes the physical and chemical parameters of the thin film through sequential processes: sputtering deposits the initial film with specific thickness and density, FeCl3 etching removes heterogenous phases by chemical dissolution, and selective oxidation converts Cu to CuO which is then removed with dilute HCl. These parameter changes transform the thin film from a sputtered structure with impurities to a highly pure cuprous oxide film with superior 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 proposed process enhances the conversion efficiency and light transmissivity of cuprous oxide solar cells by forming large Cu2O crystals and restricting the CuO-containing region to a thin surface area, leading to higher open circuit voltage and improved power generation capabilities.
Implementation Method 1
a photovoltaic conversion layer, comprising Cu2O as a main component, is formed on a first transparent electrode
Implementation Method 2
a copper layer is formed by sputtering
Data Source
AI summary
A process for manufacturing a multilayered thin film, includes: forming a photovoltaic conversion layer, comprising Cu2O as a main component, on a first transparent electrode; and placing, under a first atmosphere at an oxygen level of from 5.0×10−8 [g/L] to 5.0×10−5 [g/L] for 1 h to 1600 h, a member having the photovoltaic conversion layer formed on the first transparent electrode.