Self-Assembly In Situ Selenization Engineering to Synthesize High-Performance Ag2Se Thin Films

Abstract

Ag₂Se thin film devices have attracted significant interest in energy harvesting technologies for powering microscale systems. In this work, an in situ selenide diffusion strategy is employed to prepare Ag₂Se thin films, optimizing the carrier transport by tuning in situ synthesis temperature. The optimized carrier mobility of ∼871.43 cm^–2 V^–1 s^–1 is achieved, leading to a high room-temperature electric conductivity of ∼1235 S cm^–1. Correspondingly, a decent Seebeck coefficient (|S| > 120 μV K^–1) is obtained due to the optimal carrier concentration of approximately 1 × 10¹⁹ cm^–3. Consequently, the Ag₂Se film synthesized at 423 K exhibits a high power factor of ∼20.54 μW cm^–1 K^–2 at room temperature. A thermoelectric generator with 5 single legs is assembled by Ag₂Se thin films. This device is capable of generating an output voltage of approximately 8.58 mV and a corresponding power of approximately 3.76 nW when subjected to a temperature difference of 40 K. The study presents an effective method for enhancing the thermoelectric performance of Ag₂Se thin films.