[15p-D221-1~14] 9.5 New functional materials and new phenomena

[15p-D221-14] Elucidation of Photothermal Conversion Mechanism in H_xMoO_3−y Based on Trapped Charges and Their Dielectric Interactions

〇Ryosuke Nishikubo^1,2, Yasutaka Kuwahara^1,2,3, Shintaro Naito¹, Kazuki Kusu¹, Akinori Saeki^1,2 (1.Osaka Univ., 2.ICS-OTRI Osaka Univ., 3.JST-PRESTO)

Keywords:photothermal conversion, hydrogenated molybdenum oxide, charge recombination

Hydrogenated molybdenum suboxide (H_xMoO_3−y) is a promising material for photothermal energy conversion (PEC). However, its charge carrier dynamics and heat generation mechanism are still not clear. By using flash-photolysis time-resolved microwave conductivity, charge carrier–dielectric interactions in Pt/H_xMoO_3−y was investigated. Compared with Pt/MoO₃, H₂-reduced Pt/H_xMoO_3−y showed 3–4 orders faster recombination, indicating efficient heat generation. Furthermore, complex photoconductivity analysis revealed that Pt/H_xMoO_3−y has two types of trapping mechanisms—Drude–Zener (DZ) and negative permittivity effect (NPE) modes—depending on the reduction temperature to synthesis H_xMoO_3−y. In NPE trapping mode, electrical interaction of trapped charges with the surrounding ions and/or OH-base is significant, which retards PEC process. This is the first research revealing the carrier dynamics in hydrogenated metal oxides and their PEC mechanism.