Composite Substrate for Photovoltaic Cells
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Solution Overview
Problem
Traditional photovoltaic cell substrates, such as sodalime glass and stainless steel, are brittle, expensive, and prone to metallic contamination, leading to reduced efficiency and high scrap rates due to diffusion of impurities at high selenization temperatures.
Innovation Solution
A novel substrate made from a composite material formed by mixing a binder, such as mesophase pitch or neomesophase pitch, with a physical property enhancing material like fiber glass, which is free of metals and can be flexible or rigid, allowing for the use of carbon or silicon-based materials that withstand high temperatures without contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sodalime glass is used as substrate, then the substrate provides structural support, but it is brittle and rigid limiting applications to flat surfaces only
Solution Approach 1:
The patent employs composite substrate structures combining multiple materials to achieve both structural integrity and flexibility. The composite nature allows the substrate to maintain strength while gaining adaptability to various surface geometries, directly resolving the contradiction between rigidity and versatility.
2Reliability
If sodalime glass is used as substrate, then the substrate provides electrical insulation, but it is expensive accounting for 40% of PV fabrication cost
Solution Approach 1:
The patent substitutes expensive sodalime glass with lower-cost alternative substrate materials that can provide the necessary electrical insulation properties. This cost reduction strategy directly addresses the economic contradiction while maintaining functional reliability through material selection or protective coating layers.
3Adaptability or versatility
If stainless steel sheet is used as substrate, then the substrate provides flexibility and electrical conductivity, but it causes metallic contamination through diffusion at high selenization temperatures
Solution Approach 1:
The patent introduces barrier layers or coating materials between the stainless steel substrate and the semiconductor layers to prevent metallic contamination. These intermediary layers block diffusion pathways for Fe and Ni atoms while maintaining the substrate's flexibility and conductivity benefits, resolving the contradiction between versatility and contamination prevention.
4Manufacturing precision
If high selenization temperature (500-750°C) is used, then the semiconductor layers are properly formed, but metallic impurities diffuse rapidly through Mo grain boundaries shorting the cell
Solution Approach 1:
The patent employs barrier layers or grain boundary blocking materials that prevent metallic impurity diffusion while allowing the high-temperature selenization process to proceed. These intermediary structures maintain the necessary thermal processing conditions for proper semiconductor formation while blocking contamination pathways.
5Stability of the object's composition
If Tg of sodalime glass limits selenization temperature, then the substrate remains stable, but the process temperature range is restricted
Solution Approach 1:
The patent uses composite substrate structures or materials with higher thermal stability than sodalime glass. This allows the system to maintain substrate stability at elevated temperatures while expanding the available selenization temperature range, resolving the contradiction between compositional stability and temperature flexibility.
Data Source
AI summary
Methods of and apparatuses for making a photovoltaic cell are provided. The photovoltaic cell is able to have a substrate made of a composite material. The composite material is able to be formed by mixing a binder and a physical property enhancing material to form a mixer. The binder is able to be pitch, such as mesophase pitch. The physical property enhancing material is able to be fiber glass. The substrate of the photovoltaic cell is able to be flexible, such that the photovoltaic cell is able to be applied on various surfaces.