Silver Recovery from Amorphous/Crystalline Silicon Heterojunction Solar Cell by Alkaline Chemical Immersion and Pyrolysis

Abstract

As a typical kind of high-efficiency crystalline silicon (c-Si) solar cell, amorphous/crystalline silicon heterojunction (SHJ) solar cell is stepping into mass production currently. It is of great significance to recover Ag from unqualified, broken, and end-of-life (EoL) SHJ solar cells. Herein, a facile method including alkaline chemical immersion and pyrolysis is developed. By immersing the solar cell into a sodium hydroxide (NaOH) aqueous solution for a period of time, Ag electrodes can be peeled off effectively. The increase of the concentration (C s) and the temperature (T s) of the NaOH solution shortens the peeling-off time (t p) of the electrodes. It is deduced that the heated alkaline environment can accelerate the ester hydrolysis of the cured resin at the contact interface between Ag electrode and transparent conductive oxide (TCO) layer, which weakens the bonding strength of the Ag electrode. After cleaning, drying, and milling, the peeled-off Ag electrodes are pyrolyzed in the air at 500 °C for 60 min to remove the cured resin completely. As a result, Ag powder is obtained with high purity over 99% and almost without mass loss since it is not involved in any chemical reaction during the whole recovery process.