This Small Business Innovation Research Phase I project will develop high speed laser crystallization (HSLC) of solution deposited aluminum-doped zinc oxide (AZO) nanoparticle layers in order to reduce the manufacturing cost of thin film solar cells. AZO is a promising transparent conductive oxide (TCO). Deposition of TCO layers is one of the most expensive steps during the manufacturing process of thin film solar cells. Initial studies has already shown that HSLC crystallization of AZO layers yielded resistivity less than 3 x 10-4 ohms-cm and a maximum mobility of 380 cm2/vs (1-2 orders higher than the other deposition techniques such as sputtering). The proposed work will investigate high speed laser crystallization of AZO nanoparticles inks to prove the viability of high volume production of high performance TCO layers by HSLC of solution deposited nanoparticles. Technical milestones include: TCO deposition process speeds up to 2 orders faster over current techniques, transmission over 90% in 400-1500 nm range, and sheet resistance under 10 ohm/square. Scaling and optimization of the high-speed processes will be demonstrated on multiple large-area cells with a goal of a relative efficiency improvement of > 5% over baseline cells using a sputtered AZO layer.
The broader/ commercial potential of this project will be achieved through new equipment for integration into manufacturing to produce high-efficiency CIGS solar modules. Nearly half of the world?s CIGS solar manufacturing capacity has been established in the U.S. This SBIR development has the potential to improve manufactured CIGS solar cell efficiency by over 5% (relative) and reduce cost per watt by more than 10%. This would aid in moving flexible CIGS solar products into a market lead position, grow U.S. manufacturing, and enable large-scale adoption of solar. Integrating this technology into other PV device stack layers (such as the CIGS absorber layer) as well as the TCO layer, which is the subject of this proposal, could create over $4 billion in economic value annually by 2020. This process also has the potential to improve other commodity thin-film materials such as those used in lightweight paper batteries, organic solid state lighting, flexible displays, and RFID tags.
Project Outcome and Intellectual Merits: The Small Business Innovation Research (SBIR) Phase I project developed high speed laser crystallization (HSLC) of printed aluminum doped zinc oxide (AZO) nanoparticle layers on glass to replace indium tin oxide (ITO) for the touch panel industry. Sputter deposition of ITO layers for touch panels has been the industry standard for many years. Indium is a rare material with multiple large volume markets which have caused supply and cost variations that are no longer acceptable. In addition, sputtered ITO uses costly vacuum systems with slow growth rates during ITO deposition. Therefore there is a need for a suitable process to produce Indium-free low-cost transparent conductors for production of low cost touch screens and other thin film electronics. HSLC rapidly converts nanoparticles into crystalline films with superior properties at energy efficient conditions. Phase I results demonstrated low sheet resistances and high optical transparency with low Haze (optical scattering) near to that of industry ITO films. The advantages of this environmentally benign process include higher throughput, higher efficiency, and lower cost than traditional industrial processes. The project results have generated interest from strategic companies and venture capitalists to invest in further development. Broader impacts/commercial potential: Transparent conductive films are widely used in electronic applications such as touch panels, solar photovoltaics, liquid crystal (LCD) displays, smart glass, transparent heaters, and anti-electrostatic applications. ITO dominates the transparent conductive film market with 93% market share. Processes to form the ITO electrodes in touchscreen applications are slow and costly. Replacing these processes with the method investigated in this project enables simpler, faster, and more cost-effective production of touchscreens. According to DisplaySearch, the touchscreen market will be $32B in 2018. The sensor electrodes-on-glass portion of the touchscreen market is valued at about $3.4B. The method we propose can reduce the cost of producing sensor electrodes by 65-80%, thus creating up to several billions of dollars in economic value. Additionally, the method uses abundant materials which do not use the rare metal Indium. The chemically benign process has the potential to make vertical manufacturing of touch screens in the US viable, which is aligned with US goals to grow US manufacturing and create jobs.
