Exploring the performance and reliability of screen-printable fire-through copper paste on PERC solar cells |
Suchismita Mitra1, Steve Johnston1, Harvey Guthrey1, Peter Hacke1, William Nemeth1, Ruvini Dharmadasa2, Thad Druffel2, Kevin Elmer2, Apolo Nambo2, Dustin Williams2, Ajay Upadhyaya3, Vijaykumar D Upadhyaya3, Ajeet Rohatgi3, Paul Stradins1 1National Renewable Energy Laboratory, Golden, CO, United States /2Bert Thin Films, Louisville, KY, United States /3Georgia Institute of Technology, Atlanta, GA, United States |
In this work, we present the performance and reliability of a fire-through copper (Cu) paste which has been screen printed on c-Si solar cell with passivated emitter rear contact (PERC). The Cu paste is fired through silicon nitride (SiN) anti-reflection coating at a peak temperature of 630°C. SEM images of the Cu paste show a Cu core with ~200 nm oxide shell around the particles. This conductive oxide layer acts as a diffusion barrier between Cu and Si and prevents the degradation of cell performance during accelerated aging conditions. An efficiency of 19.25% has been achieved with Voc = 654 mV, FF = 76.68%, Jsc = 38.40 mA/cm2 for champion PERC cells. Accelerated testing of the PERC mini-modules in damp heat chamber with 85°C and 85% humidity have demonstrated that the devices are operational even after 1,500 hours. Devices with screen printed Ag contacts on the front side have been studied in parallel to the Cu contacts for comparison. |