Effect of the Molar Ratio of B2O3 to Bi2O3 in Al Paste with Bi2O3–B2O3–ZnO Glass on Screen Printed Contact Formation and Si Solar Cell Performance

In this study, eco-friendly Pb-free Bi2O3–B2O3–ZnO glass frits were chosen as an inorganic additive for the Al paste used in Si solar cells. The effects of the molar ratio of Bi2O3 to B2O3 in the glass composition on the electrical resistance of the Al electrode and on the cell performance were investigated. The results showed that as the molar ratio of Bi2O3 to B2O3 increased, the glass transition temperature and softening temperature decreased because of the reduced glass viscosity. In Al screen-printed Si solar cells, as the molar ratio of Bi2O3 to B2O3 increased, the sheet electrical resistance of the Al electrode decreased and the cell efficiency increased. The uniformity and thickness of the back-surface field was significantly influenced by the glass composition.