Substrate-Free Thermoelectric 25 μm-Thick Ag2Se Films with High Flexibility and In-Plane zT of 0.5 at Room Temperature

• Published in: ACS applied materials & interfaces Vol. 15; no. 2; pp. 3047 - 3053
• Main Authors: Lee, Dongchan, Park, Woomin, Kang, Yeong A, Lim, Hyeong Taek, Park, Seungbeom, Mun, Yeongjun, Kim, Jungwon, Jang, Kwang-Suk
• Format: Journal Article
• Language: English
• Published: American Chemical Society 18-01-2023
• Subjects: Energy, Environmental, and Catalysis Applications; flexible thermoelectrics; silver selenide; free-standing films; Ag2Se; in-plane thermal conductivity
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.2c20115

Thermoelectric inorganic films are flexible when sufficiently thin. By removing the substrate, that is, making them free-standing, the flexibility of thermoelectric films can be enhanced to the utmost extent. However, studies on the flexibility of free-standing thermoelectric inorganic films have not yet been reported. Herein, the high thermoelectric performance and flexibility of free-standing thermoelectric Ag2Se films are reported. Free-standing Ag2Se films with a thickness of 25.0 ± 3.9 μm exhibited an in-plane zT of 0.514 ± 0.060 at room temperature. These films exhibited superior flexibility compared to Ag2Se films constrained on a substrate. The flexibility of the Ag2Se films was systematically investigated in terms of bending strain, bending radius, thickness, and elastic modulus. Using free-standing Ag2Se films, a substrate-free, flexible thermoelectric generator was fabricated. The energy-harvesting capacity of the thermoelectric generator was also demonstrated.