Pb-free glass frits prepared by spray pyrolysis as inorganic binders of Al electrodes in Si solar cells

► Pb-free glass frits prepared by spray pyrolysis for Al electrodes were of fine size, spherical morphology and dense structure. ► An Al electrode formed from Al paste with glass frits had a dense structure and good adhesion to the Si substrate. ► The sheet resistances of Al electrodes formed with frits decreased from 20 to 7 mΩ sq −1 when the firing temperatures changed from 600 to 900 °C. Pb-free glass frits prepared by spray pyrolysis for Al electrodes were of fine size, spherical morphology and dense structure. Their mean size and geometric standard deviation when prepared at 1,200 °C were 1.0 μm and 1.4, respectively. Their glass transition temperature ( T g ) was 374 °C. An Al electrode formed from Al paste with glass frits had a dense structure and good adhesion to the Si substrate. It had a well-developed back-surface field layer of 17.5 μm thickness. Al electrodes formed from Al paste without glass frits had sheet resistances between 21 and 32 mΩ sq −1 as the firing temperature changed from 600 to 900 °C. This compared with values from electrodes formed with frits that decreased from 20 to 7 mΩ sq −1 over the same range of firing temperatures.