Scrutinizing the facile growth of β-Ag2Se fine films

Silver selenide thin film is one of the best candidates for thermoelectric devices. In the previous report, we demonstrated that high-performanced [201] oriented β-Ag2Se thin films can be prepared by direct metal surface element reaction (DMSER) solution selenization in a really short time at room temperature. However, the underlying mechanism of the fast reaction process were not discussed in depth. Herein, based on hard soft acid base (HASB) theory and strong oxidation, we further explored the possible reaction mechanism of the in-situ growth of β-Ag2Se thin films as the function of the reaction time. The time-dependent experimental results showed that the formation of the β-Ag2Se on elemental Ag precursor (∼690 nm thick) in Se/Na2S precursor solution is in a growth driven mode with no obvious orientation or growth rate selections to the elemental Ag precursors. Our investigations provide a prerequisite for the further preparation of thermoelectric materials with excellent properties.