Solution-processed Engineering Strategies for Chalcogenide Thermoelectric Nanomaterials
[eng] The chapters of this PhD thesis cover the work carried out in the period 2020-2024 by the PhD candidate Bingfei Nan at the Catalonia Institute for Energy Research (IREC) in Sant Adrià de Besòs, Barcelona, funded by China Scholarship Council (No. 202004910311). The thesis is mainly devoted to t...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/225446 |
| Acceso en línea: | https://hdl.handle.net/2445/225446 http://hdl.handle.net/10803/696312 |
| Access Level: | acceso abierto |
| Palabra clave: | Nanocristalls semiconductors Conversió directa de l'energia Aliatges Semiconductor nanocrystals Direct energy conversion Alloys |
| Sumario: | [eng] The chapters of this PhD thesis cover the work carried out in the period 2020-2024 by the PhD candidate Bingfei Nan at the Catalonia Institute for Energy Research (IREC) in Sant Adrià de Besòs, Barcelona, funded by China Scholarship Council (No. 202004910311). The thesis is mainly devoted to the development the high-performance and precisely controllable chalcogenide thermoelectric (TE) nanomaterials via a solution-processed bottom-up engineering strategy. This thesis is divided into five chapters. Basic research background, universal TE concepts, synthetic methods and various objectives are comprehensively introduced in the Chapter 1. The core experimental research work from Chapter 2 to Chapter 5 is presented one by one, involving a series of solution synthesis and characterization of chalcogenide TE building blocks. The work in this dissertation is based on the overall purpose of bottom-up solution processing and developing high-performance TE materials, and specifically aims to eliminate some of the major challenges in this field through the following strategies: 1) lattice thermal conductivity is reduced by various defects produced by secondary phases causing phonon scattering; 2) improvement of the Seebeck coefficient is achieved by increasing band convergence; 3) electrical conductivity is improved by increasing carrier concentration in the matrix by introducing metal nanoparticles (NPs) in a modulation doping scheme. I detail a thiol-free SnTe precursor that can be thermally decomposed to produce SnTe-Cu2SnTe3 by introducing Cu1.5Te in Chapter 2. The presence of Cu in SnTe and the segregation of the semimetallic Cu2SnTe3 phase effectively optimize the electrical conductivity while reducing the lattice thermal conductivity without affecting the Seebeck coefficient. In Chapter 3, NaSbSe2 nanocrystals (NCs) alloyed with SnTe NPs can adjust carrier concentration and band convergence. The SnTe-NaSbSe2 alloys induce multiscale defects that are beneficial to the reduction of lattice thermal conductivity. A novel colloidal quaternary Ag2SbBiSe4 is presented in Chapter 4. A modulation doping strategy based on the blending of semiconductor Ag2SbBiSe4 NCs and metallic Sn NCs is demonstrated to control the charge carrier concentration and carrier mobility. In chapter 5, I present a room temperature, aqueous-phase synthesis approach to generate Ag2Se and Bi2S3 particles, and to incorporate Bi2S3 into the Ag2Se matrix to improve the Seebeck coefficient and power factor. |
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