Springer Theses Recognizing Outstanding Ph.D. Research Chong Xiao Synthesis and Optimization of Chalcogenides Quantum Dots Thermoelectric Materials Springer Theses Recognizing Outstanding Ph.D. Research Aims and Scope The series “Springer Theses” brings together a selection of the very best Ph.D. theses from around the world and across the physical sciences. Nominated and endorsed by two recognized specialists, each published volume has been selected foritsscientificexcellenceandthehighimpactofitscontentsforthepertinentfield of research. For greater accessibility to non-specialists, the published versions includeanextendedintroduction,aswellasaforewordbythestudent’ssupervisor explainingthespecialrelevanceoftheworkforthefield.Asawhole,theserieswill provide a valuable resource both for newcomers to the research fields described, and for other scientists seeking detailed background information on special questions. 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More information about this series at http://www.springer.com/series/8790 Chong Xiao Synthesis and Optimization of Chalcogenides Quantum Dots Thermoelectric Materials Doctoral Thesis accepted by University of Science and Technology of China, China 123 Author Supervisor Dr. ChongXiao Prof. YiXie University of Science andTechnology University of Science andTechnology ofChina ofChina Hefei Hefei China China ISSN 2190-5053 ISSN 2190-5061 (electronic) SpringerTheses ISBN978-3-662-49615-2 ISBN978-3-662-49617-6 (eBook) DOI 10.1007/978-3-662-49617-6 LibraryofCongressControlNumber:2016933110 ©Springer-VerlagBerlinHeidelberg2016 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor foranyerrorsoromissionsthatmayhavebeenmade. Printedonacid-freepaper ThisSpringerimprintispublishedbySpringerNature TheregisteredcompanyisSpringer-VerlagGmbHBerlinHeidelberg Parts of this thesis have been published in the following journal articles: 1. Chong Xiao, Zhou Li, Kun Li, Pengcheng Huang, and Yi Xie* (2014) Decoupling Interrelated Parameters for Designing High Performance Thermoelectric Materials. Acc. Chem. Res. 47:1287−1295 2. Chong Xiao, Jie Xu, Kun Li, Jun Feng, Jinlong Yang, and Yi Xie* (2012) Superionic Phase Transition in Silver Chalcogenide Nanocrystals Realizing Optimized Thermoelectric Performance. J. Am. Chem. Soc. 134:4287–4293 3. Chong Xiao, Jie Xu, Boxiao Cao, Kun Li, Mingguang Kong, and Yi Xie* (2012) Solid-Solutioned Homojunction Nanoplates with Disordered Lattice: a Promising Approach toward “Phonon Glass Electron Crystal” Thermoelectric Materials. J. Am. Chem. Soc. 134:7971–7977 4. Chong Xiao, Xinming Qin, Jie Zhang, Ran An, Jie Xu, Kun Li, Boxiao Cao, Jinlong Yang*, Bangjiao Ye, and Yi Xie* (2012) High Thermoelectric and Reversible p-n-p Conduction Type Switching Integrated in Di-metal Chalcogenide. J. Am. Chem. Soc. 134:18460–18466 5. Chong Xiao, Kun Li, Jiajia Zhang, Wei Tong, Youwen Liu, Zhou Li, Pengcheng Huang, Bicai Pan,HaibinSu,andYi Xie*(2012) Magnetic Ions in Wide Band Gap Semiconductor Nanocrystals for Optimized Thermoelectric Property. Mater. Horiz. 1:81–86 ’ Supervisor s Foreword Thermoelectric materials have attracted widespread research interest, since they mayprovideanoptimizedsolutionformitigationofenergyandenvironmentcrisis due to their capability of reversibly converting heat and electricity with the advantages of being reliable, lightweight, robust, and environmentally friendly. However, the energy conversion efficiency of thermoelectric devices is far below the theoretical predictions, which suffers from their strongly inverse interrelated electrical and thermal parameters. This Ph.D. thesis study focuses on the long-standingandcrucialissueinthermoelectricmaterials:“Canwesynergistically or individually optimize the electrical and thermal transport properties in thermo- electric materials? And how?” Dr. Xiao first proposed a universal and effective strategy to optimize the ther- moelectric performance based on phase transition, a widespread phenomenon that occurs in inorganic compounds, which takes advantage of modulated electronic structure and phonon scattering across the phase transitions to decouple the power factor and thermal conductivity. Furthermore, he found a novel phenomenon that integrates of high thermoelectric performance and reversible p−n−p semiconduct- ing switching in dimetal chalcogenides semiconductors, which may open a new avenue todesignmultifunctional materials and devices.Then,he developed anew approachtomeetthe“phononglasselectroncrystal”bydesigningsolid-solutioned homojunction nanoplates in semiconductors with disordered lattices, which can significantlyreducethermal conductivitywithoutthedeterioration ofthermopower and electrical conductivity. Itisnotexaggeratedtostatethatthisthesisstudyishighlyoriginalanditsresults significantly deepen our understanding of the thermoelectric materials. This thesis has paved a way for further development of both design and characterization of materials science. Hefei, China Prof. Yi Xie August 2015 vii Acknowledgments Overtimeandwithage,fouryearsofPh.D.studycametoanendandanewstarting pointisinfrontofus;inthismoment,thewordof“gratitude”staysforefrontinmy mind throughout the day. Firstly, I owe my deepest gratitude to my respected supervisor Prof. Yi Xie. Without her enthusiasm, encouragement, continuous support, and optimism in my whole Ph.D. study, this thesis would hardly have been completed. From the selection of topics, data collection, and discussion about writing papers, in every steps of my progress, I got a lot of enthusiastic help from my supervisor. Think back, these past several years have not been an easy ride, both academically and personally. I truly thank Prof. Yi Xie for sticking by my side, even when I was irritableanddepressed.Prof.YiXiewasthereasonwhyIdecidedtogotopursuea career in research. Her profound knowledge, acute insights, modesty and rigorous scholarship,andenthusiasmandloveforteaching arecontagious.Sheshowedand stimulatedmeindifferent waystoapproacharesearchproblemandtheneedtobe persistenttoaccomplishanygoal.Here,Ipaymyhighrespectandgratitudetomy respected supervisor Prof. Yi Xie. It is a pleasure to thank Mr. Xiaobo Tian for his support in the experimental installation and routine business and for creating a cordial working environment. I thankfully acknowledge the help come from Prof. Jinlong Yang (Department of Chemical Physics), Prof. Bangjia Ye (Department of Modern Physics), and Prof. Changzheng Wu (Department of Chemistry). Thanks to my collaborators: Jie Xu, Kun Li, Youwen Liu, Zhou Li, Pengcheng Huang and other students for their assistance and cooperation during the completion of this theses, which made me feelfuninscientificresearchwork.Ialsothanktheseniorfellowapprenticesinthe laboratory:Dr.ZhenyuYao,Dr.NinaYe,Dr.ShudongZhang,Dr.YanZheng,Dr. FangDuan,Dr.YangXu,Dr.LeiZheng,Dr.YongfuSun,Dr.LiangLiu,Dr.Min Zhou,Dr.YanXue,andDr.JianWu;graduatesofthesameyear:XiaodongZhang, Haiou Zhu, Liangfei Bai, and Jinbao Zhu; and also junior fellow apprentices: Junfeng Xie, Lin Liang, Ran Long, Xiao Gang, Chengming Wang, Meili Guan, Hangmin Guan, Conghai Deng, Jian Bao, Xu Sun, Feng Feng, Wentuan Bi, Kun ix x Acknowledgments Xu, HuXin, Jiajia Zhang, Shan Gao, Zejun Li, Xiao Xie, Xiaojiao Zhu, Xiuli Lu, FengcaiLei,QinLiu,HuiWang,ShuangLi,JingLiang,andPengzuoChen.Ialso thank the wonderful staff in the USTC for always being so helpful and friendly. People here are genuinely nice and want to help you out and I am glad to have interacted with many. Theauthorwouldalsoliketothankallthepresentmembersofthephysicaland chemical test center, especially Guien Zhou, Shuyuan Zhang, Xianming Liu, Tanwei Li, Xiaoming Feng, Yunbo Jia, Shengquan Fu, Ming Li, Jianliu Huang, Yanwei Ding, Jian Zuo, Yi Jin, Minghua Yu, Bo Pan, Jiyin Zhao, and Wanqun Zhang,fortheirhelpinmaterialtestingandforcompletingthisthesis.Thanksgoto Xinming Qin from the department of chemical physics and Jie Zhang, Shaojuan Fan,andRanAnfromthedepartmentofmodernphysics,fortheirpowerfulhelpin theoretical calculation and special material characterization. I would never have got to the position of being able to do a Ph.D. without my parents, wife, and sister, who always encouraged me to achieve my full potential andprovidedgenerouscareandmoralsupportineverypossiblewaythroughoutmy education. The warmth offamily has been and will always be the strong backing behind my life. It is difficult to pay them back with simply words. Without them, I would not have remained as motivated as I did throughout various stages of the work, and I dedicate this thesis to them. Finally, I would like to express my gratitude to all those who have cared, embosomed,andhelpedmeinmystudy.Thisthesiswouldnothavebeenpossible without the inspiration and support of a number of wonderful individuals—my thanks and appreciation to all of them for being part of this journey. Hefei, China Chong Xiao May 2013 Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Thermoelectric Effect and Applications. . . . . . . . . . . . . . . . . . . 2 1.3 Performance Parameters of Thermoelectric Materials . . . . . . . . . 4 1.4 Progress in Optimization of the Thermoelectric Parameters. . . . . 6 1.4.1 Individual Parameter Modulation. . . . . . . . . . . . . . . . . . 6 1.4.2 Two Parameters Synergistic Modulation. . . . . . . . . . . . . 11 1.4.3 Three Parameters Synergistic Modulation. . . . . . . . . . . . 21 1.5 Our Main Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2 Superionic Phase Transition Optimizing Thermoelectric Performance in Silver Chalcogenide Nanocrystals . . . . . . . . . . . . . 35 2.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 2.2 Results and Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 2.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3 Two Metal Ion Exchange Realizing Efficient Thermoelectric Properties and p–n–p Conduction Type Transition . . . . . . . . . . . . 51 3.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.2 Results and Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.3 Conculsion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4 Toward “Phonon Glass Electron Crystal” in Solid-Solutioned Homojunction Nanoplates with Disordered Lattice . . . . . . . . . . . . 65 4.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 4.2 Results and Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.3 Conculsion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 xi