Salah Bedair, professor of electrical and computer engineering at North Carolina State University, recently published and presented his research on multi-junction solar cells. While these cells boast the market's highest efficiency—up to 45%—they are extremely complicated and expensive to manufacture because different materials cannot simply be stacked. While current solutions use heavily doped metals to create tunnel junctions between layers, the research focuses on utilizing intermetallic bonding to bond solar cells made of different materials, for which Professor Bedair has a pending patent application.

Although multi-junction solar cells may not be cost-efficient yet, several companies have recent patent documents for them, including Alta Devices, Ascent Solar, Boeing, Soitec, and SolAero. Innovations such as Professor Bedair's research are expected to increase patent activity related to multi-junction solar cells in the private sector. While some companies are clearly interested in the technology already—as indicated by their IP investment—more entities may enter this specific market given the high potential of stacked photovoltaics.