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Electrical Characterization of Nano-Colloids in Si Solar Cell Screen-Printed Contacts by Conductive Atomic Force Microscopy (C-AFM)
K. Ren, D. Han, A. Ebong
Contact, Electrical Properties, Silicon Solar Cell(s), characterization, Interfaces
Silicon Materials and Cells
Subtopic: Characterisation & Simulation of Si Cells
Event: 36th European Photovoltaic Solar Energy Conference and Exhibition
Session: 2DO.6.6
286 - 289
ISBN: 3-936338-60-4
Paper DOI: 10.4229/EUPVSEC20192019-2DO.6.6
0,00 EUR
Document(s): paper


The glass layer thickness and conductivity at the Si/Ag gridline interface of a screen-printed solar cell can limit the application of fire through dielectric contacts to the lowly doped emitter which is critical to enhance the efficiency. In order to reduce cost and advance the penetration of PV electricity by decreasing the associated resistance and increasing the fill factor and efficiency, the glass layer needs to be conductive, irrespective of the thickness. This paper reports the microstructural and electrical characterization of the glass layer at the Si/Ag gridline interface to elucidate its conductivity and thickness. Microscopy analysis was used to confirm that after the Ag gridline removal, the glass layer found underneath the Ag gridlines was thick (>300 nm) and encapsulated nano-colloids. STEM revealed the nano-colloids contained high concentration of Ag, Pb and Te with small amount of Si glass. The C-AFM showed that the thick glass layer had micro-size conductive areas which correspond to the nano-colloids and from the I-V curve, the specific contact resistance of the nano-colloids was estimated as 4.93~26.94×10-4 Ω·cm2. The I-V curve modeled according to the modified Fowler-Nordheim tunneling (FNT) showed low barrier height of 0.1 eV, which corresponds to a layer thickness of ~17 nm.