Decreasing Electrical Resistivity of Ag Film by Low-Temperature Evaporation and Sintering through Azeotrope Application

Abstract

In the temperature-sensitive components, such as perovskite solar cells, large-area electrical connections with high electrical conductivity are also required. To fulfill the requirements, low-temperature evaporation was realized by preparing binder-free pastes with Ag flakes and a solvent mixture, followed by sintering at 140 °C. The mixed solvent was based on viscous α-terpineol with the addition of an appropriate amount of dipropylene glycol methyl ether acetate or diethylene glycol diethyl ether to achieve an azeotrope composition, followed by the addition of a low-molecular-weight hydroxypropyl cellulose to increase the viscosity and thixotropy. During sintering at 140 °C in air for up to 30 min, the paste with 49.5 wt% α-terpineol, 49.5 wt% dipropylene glycol monomethyl ether acetate, and 1 wt% hydroxypropyl cellulose mixture exhibited an excellent electrical conductivity of 7.72 × 10−6 Ω·cm despite the implementation of low-temperature sintering. The excellent processability of the prepared Ag-based pastes at 140 °C demonstrated their potential for novel application areas.

Keywords

• binder-free Ag paste
• viscous solvent
• hydroxypropyl cellulose
• azeotrope composition
• electrical resistivity
• low-temperature evaporation