SPLTRAK Abstract Submission
Rear Junction Bifacial Screen-Printed Double Side Passivated Contact Si Solar Cells 
Young-Woo Ok1, Vijaykumar D Upadhyaya1, Rounsaville Brian1, Ajay D Upadhyaya1, Ajeet Rohatgi1, Gabby De Luna2, John Derek Arcebal2, Pradeep Padhamnath2, Shubham Duttagupta2, Wook-Jin Choi1
1Georgia Institute of Technology, Atlanta, GA, United States
/2Solar Energy Research Institute of Singapore, 7 Engineering Drive 1, Singapore

We report on the fabrication of fully screen-printed bifacial large area (244 cm2) ~20.6% efficient rear junction cells with full area poly-Si/SiOx passivating contacts on both sides. A full area thin n-TOPCon (~35 nm) was deposited on the textured front side in conjunction with thick p-TOPCon (~250 nm) on the planar rear side using LPCVD grown intrinsic poly-Si and ex-situ doping technology.  Excellent iVoc of ~730 mV was achieved on the cell precursor after SiNx capping layers on both sides, prior to metallization. However, iVoc dropped from 730 to 715 mV after a simulated high-temperature firing process (>700 °C) without metallization. This was mainly due to the degradation of n-TOPCon passivation quality after the firing cycle without the metal paste. After fire through screen-printed contact formation, a preliminary efficiency of ~20.6% was achieved with full area double side TOPCon (DS-TOPCon) cell structure with a high Voc of ~700 mV and excellent contact resistance. Further optimization of paste and firing is in progress on screen-printed 20-30 nm n-poly-Si and will be presented at the conference.