Doped Titanium Oxide Coating for Solar Cell Efficiency
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Solution Overview
Problem
Current solar cell technologies face inefficiencies at the interface between the transparent conductive oxide (TCO) layer and the active layer, such as amorphous silicon or cadmium-telluride, due to limitations in the electrical conductivity and stability of the existing TCO layers, which hinders the conversion efficiency of solar cells.
Innovation Solution
A method of depositing a doped titanium oxide coating using atmospheric chemical vapor deposition during the float glass manufacturing process, incorporating a halogenated inorganic titanium compound, an organic oxygen-containing compound, and a halogenated niobium or tantalum dopant, achieving an electrically conductive titanium oxide film with a conductivity of greater than 1×10−3 S/cm, which is applied as a coating on a glass substrate for use in solar cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chemically stable titanium oxide layer is added between the TCO and active layer, then the conversion efficiency of solar cells is improved, but the device complexity increases
Solution Approach 1:
The patent changes the chemical composition parameters of the titanium oxide layer by incorporating group 5B metal dopants (niobium or tantalum) at controlled concentrations (0.1-5.0 atomic percent). This doping modifies the electrical and optical parameters of the TiO2 layer, achieving enhanced conductivity and stability without requiring additional complex layer structures.
Solution Approach 2:
The patent creates a composite material system by combining titanium oxide with group 5B metal dopants within a single layer. This composite approach allows the material to exhibit both the chemical stability of TiO2 and the enhanced electrical conductivity provided by the dopant, resolving the contradiction between stability and efficiency without increasing structural complexity.
2Reliability
If dopants are added to titanium oxide to enhance electrical conductivity, then the conversion efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter ranges for dopant concentration (0.1-5.0 atomic percent) that balance electrical conductivity enhancement with manufacturing feasibility. Within this range, the dopant provides sufficient conductivity improvement while remaining tolerant to normal manufacturing variations, avoiding the need for ultra-precise control.
Solution Approach 2:
The patent employs a moderate dopant concentration range rather than maximizing dopant content. This partial action approach provides sufficient conductivity enhancement for improved conversion efficiency while maintaining ease of manufacture and avoiding the precision challenges associated with very low or very high dopant concentrations.
3Productivity
If atmospheric chemical vapor deposition is used during float glass manufacturing, then the productivity is improved, but the manufacturing precision of coating thickness may be compromised
Solution Approach 1:
The patent optimizes the deposition parameters including temperature range (400-700°C), dopant concentration (0.1-5.0 atomic percent), and precursor ratios to achieve a deposition rate greater than 35 Å/sec. These parameter adjustments enable high-speed deposition while maintaining coating thickness uniformity suitable for solar cell manufacturing.
Solution Approach 2:
The patent implements continuous atmospheric chemical vapor deposition during the float glass manufacturing process rather than using batch processing. This continuous deposition method maintains stable coating quality and thickness uniformity while achieving high productivity, as the deposition occurs continuously alongside glass production without interruption.
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 doped titanium oxide coating significantly reduces solar radiation reflection by 0.5-2.0% and enhances the conversion efficiency of solar cells by 7-12%, making it a cost-effective and commercially viable solution for large-scale solar cell manufacturing.
Implementation Method 1
a method of making a doped titanium oxide coating by atmospheric chemical vapor deposition
Implementation Method 2
The heat input from the glass ribbon causes the precursor gas mixture to chemically react so as to form a pyrolytic, doped titanium oxide coating
Data Source
AI summary
A method of making a doped titanium oxide coating in a float glass manufacturing process and the coated glass article made thereby wherein the dopant is a niobium or tantalum compound. The doped titanium oxide coating preferably exhibits an electrical conductivity>1×10−3 S/cm.