[8a-Z18-1~11] 9.4 Thermoelectric conversion

▲ [8a-Z18-11] Formamidinium doped CsSnI₃ perovskite for thermoelectric applications

〇Ajay Kumar Baranwal¹, Shrikant Saini², Tomohide Yabuki², Qing Shen¹, Koji Miyazaki², Shuzi Hayase¹ (1.Univ of Electro-Comm, 2.Kyushu Inst. Tech.)

Keywords:Perovskite, CsSnI3, Thermoelectric devices

Halide perovskite materials (AMX₃; A=CH₃NH₃⁺, NH₂CHNH₂⁺/FA⁺; M=Pb²⁺, Sn²⁺; X=I^-) have found paramount attraction in thermoelectric study owing to ultra-low thermal conductivity, which appears because of the rattling phenomenon of A–site, surrounded by MX₆ octahedra. The tuning of A-site cation alters the crystal packing density and the Gold-Smith tolerance factor would be influenced to mediate the electronic properties.
Inorganic CsSnI₃ crystal has been widely discussed recently due to promising thermoelectric applications owing to high electrical conductivity and ultra-low thermal conductivity. However, its poor tolerance factor (0.816) shows CsSnI₃ crystal is much strained. Here, we study the thermoelectric properties of perovskite crystal under the influence of tuning of A-site with large radius cation FA⁺. The A-site doping improves the tolerance factor, alters the electronic and thermoelectric properties of perovskite crystal. A series of Cs_xFA_1-xSnI₃ thin films have been fabricated and the resulting thermoelectric performance is studied. The details will be discussed in the conference.