Low Conductivity Decay of Sn-0.7Cu-0.2Zn Photovoltaic Ribbons for Solar Cell Application

Kuan-Jen Chen; Fei-Yi Hung; Truan-Sheng Lui; Lin Hsu

doi:10.3390/mi10080550

Low Conductivity Decay of Sn-0.7Cu-0.2Zn Photovoltaic Ribbons for Solar Cell Application

Micromachines (Basel). 2019 Aug 19;10(8):550. doi: 10.3390/mi10080550.

Authors

Kuan-Jen Chen¹, Fei-Yi Hung², Truan-Sheng Lui³, Lin Hsu³

Affiliations

¹ Instrument Center, National Cheng Kung University, Tainan 701, Taiwan.
² Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan. fyhung@mail.ncku.edu.tw.
³ Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan.

Abstract

: The present study applied Sn-0.7Cu-0.2Zn alloy solders to a photovoltaic ribbon. Intermetallic compounds of Cu₆Sn₅ and Ag₃Sn formed at the Cu/solder/Ag interfaces of the module after reflow. Electron probe microanalyzer images showed that a Cu-Zn solid-solution layer (Zn accumulation layer) existed at the Cu/solder interface. After a 72 h current stress, no detectable amounts of Cu₆Sn₅ were found. However, a small increase in Ag₃Sn was found. Compared with a Sn-0.7Cu photovoltaic module, the increase of the intermetallic compounds thickness in the Sn-0.7Cu-0.2Zn photovoltaic module was much smaller. A retard in the growth of the intermetallic compounds caused the series resistance of the module to slightly increase by 9%. A Zn accumulation layer formed at the module interfaces by adding trace Zn to the Sn-0.7Cu solder, retarding the growth of the intermetallic compounds and thus enhancing the lifetime of the photovoltaic module.

Keywords: Sn–0.7Cu–0.2Zn; Zn accumulation layer; intermetallic compounds; photovoltaic ribbon.