Dong YANG PhD defense
Optimization of chalcogenide thin films for flexible thermoelectric devices
Wednesday 17 December, 09:30
Glasses and Ceramics (V&C) team
Abstract
Thermoelectric devices can directly convert thermal energy into electricity. With the rapid development of wearable electronics, both self-powering capability and mechanical flexibility of such devices are essential. Conventional chalcogenide materials, such as Bi2Te3 and Sb2Te3, exhibit excellent thermoelectric performance near room temperature but suffer from poor flexibility due to the lack of sufficient slip planes for stress relaxation during bending. To address these challenges, this work proposes a multidimensional regulation strategy. First, chalcogenide thin films were fabricated via physical vapor deposition and integrated with flexible substrates. Subsequently, hybridization and doping were employed to enhance thermoelectric properties. Specifically, incorporating MAPbI3 into Bi2Te3 and Sb2Te3 induces interfacial diffusion and micro strain effects, which improve carrier mobility and preferred orientation. Al doping in Cu2Se broadens the bandgap and optimizes the power factor, while Te doping in Ag2Se promotes oriented growth and beneficially tunes electrical transport through doping effects. Finally, neutral-axis engineering was implemented, by placing the thermoelectric films near the neutral plane to minimize bending stress and reduce crack formation during deformation, thereby significantly enhancing the flexibility and cycling stability of the thin films and devices. High-performance and flexible thermoelectric thin films and devices have been obtained.
Jury
Prof. Shu-fang WANG, Professor, Hebei University / Reviewer
Prof. Antoine MAIGNAN, Research Director, CNRS, CRISMAT / Reviewer
Prof. Bruno BUREAU, Professor, University of Rennes, ISCR / Examiner
Prof. Chang-gui LIN, Professor, Ningbo University / Examiner
Prof. Xiang-hua ZHANG, Research Director, CNRS, University of Rennes, ISCR / PhD Supervisor
Prof. Zhuang-hao ZHENG, Professor, Shenzhen University / PhD Co-Supervisor
Contacts
Xiang-hua ZHANG, xiang-hua.zhang@univ-rennes.fr
