This Small Business Innovation Research (SBIR) Phase II project is directed at developing a real time process control system for improving manufacturing of thin film products such as thin film solar panels, solid state lighting, touch screen displays, optics and telecommunications. Photovoltaics are a vital component of the renewable energy mix but they need to be more efficient to be competitive against existing fossil fuel approaches. The system will be able to dynamically control and correct the film deposition process in order to keep each product within its targeted specification, reducing and even eliminating rejects. It allows manufacturing of more consistent and uniform solar panels resulting in higher solar conversion efficiency, reduced cost and increased manufacturing yield. The objective of this Phase II is to further develop and improve the prototype system developed under Phase I and IB and validate it for two most common thin film solar panel manufacturing configurations. This project will complete the hardware / software development and validation for monitoring film growth for amorphous silicon solar panel manufacturing. Phase II will remove technical risk allowing fast commercialization of the monitoring system. Additional development will be performed to finalize the control component of the system.
The broader impact/commercial potential of this project is to advance the scientific understanding of how thin films grow during deposition. It will help thin film solar panel manufacturers to develop higher quality products. The system will improve production accuracy, reduce production flaws and make the manufacturing process less susceptible to process parameter drifts and errors,especially for advanced thin-film products. The commercial impact of the project is that manufacturers will (i) increase solar panel efficiency and manufacturing yield, (ii) reduce manufacturing cost, and (iii) increase revenue and profit. The proposed technology provides an innovative platform solution that can be further improved in order to achieve waste-free thin film manufacturing with little human interaction. This system, if adopted by only 30% of the thin film manufacturers will result in roughly $1 billion in savings by 2015. The societal impact of the project is to help make solar panels a competitive source of energy against existing fossil fuel approaches. The system will allow manufacturers to meet the market demand for lower cost solar products which will accelerate PV adoption worldwide thus helping to reduce global warming and reduce our dependence on oil.
Solar cells are measured by how much they cost for the power they produce ($/W); thus the way to make them more affordable is to reduce their manufacturing cost and/or increase the power they generate. The main reasons for the large inefficiency of manufactured large-size thin film solar panels involve (1) the non-uniformity of the film thickness and (2) the non-homogeneity of various physical parameters, both within depth of the film and over the large areas of the solar panel. Most of the optical control systems on the market are not able to control these non-uniformities and non-homogeneities as the films are being deposited. As a result, a significant amount of material, energy, and labor are wasted, which inflates the final product cost and delays achieving grid parity where solar energy costs are equal to traditional energy sources. During this Phase II SBIR project we have developed, installed and validated in real operation a prototype of a real-time optical monitoring and process control system able to reduce waste and improve the manufacturing yield and conversion efficiency of thin film solar cells and panels. The resulting system is able to monitor important thin film solar panel parameters and their uniformity during the film deposition inside the manufacturing equipment. As films are deposited on the large size panel, the prototype system detects film thickness and its non-uniformity, the rate of deposition and its consistency, the film optical constants and their inhomogeneity over the panel area. A working prototype was demonstrated at the facility of US amorphous silicon solar panel manufacturer (superstrate process), as well as in manufacturing of crystalline silicon solar cells and copper-indium-galium de-selenide solar panels (substrate process). The technology has also been demonstrated for both moving and stationary substrates during deposition. Over 8% relative efficiency improvement has been demonstrated for thin film solar panels and about 3% relative efficiency improvement for crystalline silicon solar cells. During a supplemental extension of Phase II the project has expanded to developing a similar technology applied to a broader thin film products such as large size functional glass panels and a novel process for antireflective coating on crystalline silicon solar cells. Significant steps have been made to commercialize this technology in both thin film and crystalline silicon solar industry. The developed technology provides a platform solution that can lead to lean manufacturing of thin film based products. The proposed technology is able to (1) increase the cost effectiveness of solar energy compared to traditional carbon-based sources of energy; (2) help reduce energy consumption and greenhouse gas emissions needed for the new green economy; and (3) facilitate the development of numerous other applications for next generation thin-film-based products such as photonic crystals, nanotechnology, meta-materials, multi-junction solar cells, printing, and counterfeiting control.
