High-performance thermoelectric silver selenide thin films cation exchanged from a copper selenide template

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Chemistry

Background:

• Silver selenide (Ag2Se) is an n-type semiconductor with significant potential for thermoelectric applications.
• Existing methods for synthesizing nanostructured Ag2Se are often energy-intensive, time-consuming, and yield poor results.
• There is a need for cost-effective and efficient synthesis routes for Ag2Se to realize its thermoelectric potential.

Purpose of the Study:

• To develop a low-cost, solution-processed method for fabricating Ag2Se thin films.
• To investigate the thermoelectric properties of Ag2Se produced via a novel cation exchange method.
• To explore Ag2Se as a viable alternative to toxic or expensive thermoelectric materials.

Main Methods:

• Fabrication of copper selenide (Cu2Se) thin films using thiol-amine dissolution of bulk Cu2Se.
• Cation exchange reaction by soaking Cu2Se films in silver nitrate (AgNO3) solution at room temperature.
• Annealing of the resulting films to form Ag2Se.
• Characterization of thermoelectric properties, including power factor (PF) and figure of merit (ZT).

Main Results:

• Successfully synthesized Ag2Se thin films from Cu2Se templates via a room-temperature cation exchange process.
• Achieved an average power factor (PF) of 617 ± 82 μW m⁻¹ K⁻² and a ZT value of 0.35 at room temperature.
• Obtained a maximum PF of 825 μW m⁻¹ K⁻² and a ZT value of 0.46 at room temperature for the best-performing film.
• Demonstrated high thermoelectric performance achievable through a fully solution-processed route without hot-pressing.

Conclusions:

• The developed two-step, solution-processed method offers a cost-effective and efficient route to Ag2Se thin films.
• The synthesized Ag2Se exhibits promising thermoelectric performance at room temperature.
• This approach provides a viable pathway for scalable production of Ag2Se for thermoelectric applications.