Metal Matrix Composite Solar Cell Metallization

¹ Space Vehicles Directorate, Air Force Research Laboratory 3550 Aberdeen Ave SE, Kirtland Air Force Base, NM 87111, USA
² The University of New Mexico, Albuquerque, NM USA
³ Rochester Institute of Technology, Rochester, NY, USA
⁴ SolAero Technologies Corp, Albuquerque, NM, USA

AFRL.VSSVOrgMailbox@us.af.mil

Abstract

Advanced solar cells are moving to ever thinner formats in order to save mass and in some cases improve performance. As cells are thinned, the possibility that they may fracture or cleave due to mechanical stresses is increased. Fractures of the cell can degrade the overall device performance if the fracture propagates through the contact metallization, which frequently occurs. To address this problem, a novel semiconductor metallization system based on multi-walled carbon nanotube (CNT) reinforcement, termed metal matrix composite (MMC) metallization is under investigation. Electro-mechanical characterization of MMC films demonstrate their ability to provide electrical conductivity over >40 micron wide cracks in the underlying semiconductor, with the carbon nanotubes bridging the gap. In addition, these materials show a “self-healing” behaviour, electrically reconnecting at ~30 microns when strained past failure. Triple junction (TJ) space cells with MMC metallization demonstrated no loss in J_sc after intentional fracture, whereas TJ cells with conventional metallization suffer up to 50% J_sc loss.