Researchers develop new manufacturing process for ultrathin flexible crystalline silicon solar cells

In February, researchers at the U.S. Navy Research Laboratory (NRL) submitted a patent application for a new method of manufacturing ultrathin flexible silicon solar cells.

The new manufacturing method alters off-the-shelf crystalline silicon cells in a way that allows them to curve while still maintaining adequate performance at a reasonable cost. Many commercially available silicon solar cells are bulky and glass-like, rendering them unsuitable for many military applications because bending can damage them.

Solar cells created by this method could provide critical flexibility for power generation for both commercial and military applications, according to Dr. Woojun Yoon, NRL electrical engineer and principle researcher.

“Solar-powered systems are critical to enhance operational capability, improve energy efficiency, and reduce reliance on supply lines for fuel,” said Yoon.

NRL electrical engineer Dr. Woojun Yoon, displays an ultrathin flexible crystalline silicon solar cell that underwent a manufacturing process developed by NRL to thin the cell. The patent-pending method reduces the total thickness of a commercially available cell to approximately 30 microns and ensures its silicon surface won’t crack when bent.

NRL electrical engineer Dr. Woojun Yoon, displays an ultrathin flexible crystalline silicon solar cell that underwent a manufacturing process developed by NRL to thin the cell. The patent-pending method reduces the total thickness of a commercially available cell to approximately 30 microns and ensures its silicon surface won’t crack when bent.

The process mechanically thins commercial off-the-shelf crystalline silicon solar cells that have rear-junctions and rear contacts, so-called interdigitated back contact (IBC) solar cells. Contacts on the back of the cell reduce shadow impacts and yield additional power. The off-the-shelf solar cells that researchers are altering in this process are already highly efficient, yet not as readily available as other solar cells.

“We developed low cost cells to expand the range of application that solar cells can be used for, including unmanned aerial vehicles, mobile solar markets, and other military applications,” said co-inventor and electrical engineer David Scheiman. “Private industry could also integrate this technology into their products, such as homes and cars.”

The new process is the second ultrathin solar cell manufacturing design by the researchers. In early December 2018, they submitted a patent application for a method of manufacturing ultrathin flexible mono- and multi-crystalline silicon solar cells. That method reduces the total thickness of a commercially available cell to approximately 30 microns and ensures its silicon surface won’t crack when bent.

“By using commercially available crystalline solar cells we can convert those thick cells into thin flexible crystalline solar cells with minimum performance losses,” Yoon explained. “The main application is for mobile solar powered generation systems such as transportable solar blankets and unmanned vehicles.”

NRL researchers developed these innovations as part of an ongoing effort to identify solar capability that will meet the cost constraints and capability demands to power equipment for the U.S. Navy, U.S. Marine Corps and other Department of Defense organizations. The implementation of these solar cell technologies could help reduce reliance on fossil fuels and traditional batteries for powering and charging devices.

For more information about how to participate in a cooperative agreement with the NRL to use this technology contact the technology transfer office at https://www.nrl.navy.mil/techtransfer/contact.