Development of Low-Cost, Crack-Tolerant Metallization Using Screen Printing
Omar K Abudayyeh1, Andre Chavez1,2, John Chavez1, Sang M Han1,2, Francesco Zimbardi3, Brian Rounsaville3, Vijay Upadhyaya3, Ajeet Rohatgi3, Byron McDanold4, Timothy Silverman4
1Osazda Energy, LLC, Albuquerque, NM, United States
/2University of New Mexico, Albuquerque, NM, United States
/3Georgia Institute of Technology, Atlanta, GA, United States
/4National Renewable Energy Laboratory, Golden, CO, United States

One of the ways to reduce the cost of solar electricity to 3¢/kWh, thus reaching parity with fossil-fuel-based generation, is to reduce the degradation rate of solar modules and extend their lifetime well beyond 30 years. The extended module lifetime in turn can positively influence the financial model and the bankability of utility-scale PV projects. Today, the highest-risk-priority solar module degradation mechanism is what is known as hot spots, often induced by cell cracks. In order to address this degradation mechanism, we make use of low-cost, multi-walled carbon nanotubes embedded in commercial screen-printable silver pastes. When the carbon nanotubes are properly functionalized and appropriately incorporated into commercial silver pastes, the resulting metal contacts on solar cells, after screen-printing and firing, show exceptional fracture toughness. These composite metal contacts possess increased ductility, electrical gap-bridging capability up to 50 µm, and “self-healing” to regain electrical continuity even after cycles of complete electrical failure under extreme strain.