Highly decorative, lightweight flexible solar cells for automotive applications 2019-01-0863
In 2012, the U.S. Environmental Protection Agency and National Highway Traffic Safety Administration laid down strict standards for CO2 emissions and improved fuel economy for light-duty vehicles covering the model years 2017 to 2025. In order to meet the requirement, it is essential to develop an alternative power source for the future cars. Power generation by solar cells/modules is a promising renewable energy candidate because the most environmentally friendly vehicles such as electric vehicles and plug-in hybrid vehicles are equipped with large-capacity batteries that can be charged with electricity generated by solar cells/modules. In this study, we developed a simple lift-off process for producing colorful, light-weight, and flexible Cu(In,Ga)Se2 (CIGS) solar cells for automotive application. The developed lift-off process consists of three steps: first, attaching a plastic film on CIGS/glass solar cell at temperature of around 100 °C; second, scribing the cell to the desired area/shape after cooling down; and finally, a back contact is deposited on detached layers. Our measurements show that the fabricated lift-off cells have nearly identical performance compared to that of the cell before the lift-off process, suggesting the validity of the developed lift-off process for producing flexible and light-weight CIGS solar cells. The colors were generated on the cells by coating the highly transparent automotive paint on the plastic films. The glass-flake pigments were found to exhibit bright, uniform, and solid appearance on the flexible CIGS solar cells with small output power reduction of less than 5% compared to the cells before the lift-off process for chromatic colors. We believe that the highly decorative, flexible, and light-weight solar cells produced by the developed process can considerably increase the installable area of solar cells/module on the vehicles.