مشخصات پژوهش

عنوان	Ultra-low lattice thermal conductivity and high thermoelectric efficiency in Cs2SnX6 (X=Br, I): A DFT study
نوع پژوهش	مقاله چاپ شده
کلیدواژه‌ها	Phonon transport ; Thermoelectric properties ; Relaxation time ; First-principles calculations ; Vacancy-ordered double perovskite ; Cs2SnX6 (X=Br, I)
چکیده	High-performance thermoelectric materials provide an environmentally friendly route for future large-scale electricity production from waste heat recovery. In this work, we present an in-depth analysis of electronic, phononic, and thermoelectric properties of vacancy-ordered double perovskite Cs2SnX6 (X = Br, I) compounds based on generalized gradient approximations (GGA) and post-density functional theory treatments. We find that the optical phonon scattering mechanism plays a more critical role than the acoustical phonon and impurity scattering in both materials’ transport properties. These materials also exhibit a relatively large Seebeck coefficient and ultra-low lattice thermal conductivity about 0.123/0.062 W/mK for Cs2SnBr6/Cs2SnI6 at room temperature calculated by single relaxation time model (SMRT). Such ultra-low lattice thermal conductivity arises from significant phonon-phonon scattering due to highly overlapped acoustic and optical phonon branches around ~1 THz. This occurrence introduces the Cs atom’s rattling motion inside [SnX6]2- (X = Br, I) cages. The most considerable ZT values with the SMRT method at 300/500 K are about 0.32/0.82 for Cs2SnBr6 and 0.9/1.96 for Cs2SnI6. Our theoretical results suggest that both compounds have a great potential to be good candidates for thermoelectric materials and can be used to guide experimental investigation to obtain the optimal ZT performance.
پژوهشگران	حسین میلانی مقدم (نفر دوم)، مهدی فلاح (نفر اول)