A comprehensive review on Bi₂Te₃‐based thin films: Thermoelectrics and beyond

Abstract

Bi2Te3‐based materials are not only the most important and widely used room temperature thermoelectric (TE) materials but are also canonical examples of topological insulators in which the topological surface states are protected by the time‐reversal symmetry. High‐performance thin films based on Bi2Te3 have attracted worldwide attention during the past two decades due primarily to their outstanding TE performance as highly efficient TE coolers and as miniature and flexible TE power generators for a variety of electronic devices. Moreover, intriguing topological phenomena, such as the quantum anomalous Hall effect and topological superconductivity discovered in Bi2Te3‐based thin films and heterostructures, have shaped research directions in the field of condensed matter physics. In Bi2Te3‐based films and heterostructures, delicate control of the carrier transport, film composition, and microstructure are prerequisites for successful device operations as well as for experimental verification of exotic topological phenomena. This review summarizes the recent progress made in atomic defect engineering, carrier tuning, and band engineering down to a nanoscale regime and how it relates to the growth and fabrication of high‐quality Bi2Te3‐based films. The review also briefly discusses the physical insight into the exciting field of topological phenomena that were so dramatically realized in Bi2Te3‐ and Bi2Se3‐based structures. It is expected that Bi2Te3‐based thin films and heterostructures will play an ever more prominent role as flexible TE devices collecting and converting low‐level (body) heat into electricity for numerous electronic applications. It is also likely that such films will continue to be a remarkable platform for the realization of novel topological phenomena.

High thermoelectric performance realized through manipulating layered phonon-electron decoupling

“…The thermoelectric performance is determined by a dimensionless figure of merit ZT ¼ S 2 sT =k tot , where S is the Seebeck coefficient; s is the electrical conductivity; T is the temperature in kelvin; and k tot is the total thermal conductivity, which includes the lattice thermal conductivity k lat and the electronic thermal conductivity k ele (5). Although the complex interrelationships between these parameters pose a challenge for optimizing thermoelectric performance (6,7), after decades of effort, researchers have developed several strategies to resolve it, including band structure engineering to enhance electrical transport properties (8)(9)(10), designing multidimensional defects to suppress thermal conduction (11)(12)(13), and exploiting intrinsically low-thermal conductivity materials to focus on the optimization of electrical transport properties (14)(15)(16)(17). Owing to these strategies, thermoelectric materials with ZT max values beyond 2.0 are no longer as rare as they were decades ago.…”

Organic/Inorganic Hybrid Design as a Route for Promoting the Bi0.5Sb1.5Te3 for High‐Performance Thermoelectric Power Generation

“…[4,5] Bismuth telluride (Bi 2 Te 3 ) and its alloys are state-of-the-art room-temperature TE materials, and are quite promising for low-grade waste heat recovery. [6][7][8][9][10][11] Persistent efforts have been devoted to improving their zT values, including manipulation of the fabrication processes, [12,13] fine-tuning the chemical doping, [14][15][16][17][18][19][20][21][22][23][24][25][26][27] and nanostructuring. [13] In particular, enhanced average zTs have been obtained in Bi 2 Te 3 -based composites with various kinds of nano-carbon materials, for example, carbon nanotubes, [28][29][30] carbon fibers, [31] and nano-SiC.…”

Regulating the Configurational Entropy to Improve the Thermoelectric Properties of (GeTe)1−x(MnZnCdTe3)x Alloys

“…The energy conversion efficiency of the TE device is determined by the component materials’ dimensionless figure of merit, zT = α 2 σT / κ , where T , α , σ and κ denote the absolute temperature, Seebeck coefficient, electrical conductivity and thermal conductivity (including carrier component κ e and lattice component κ L ), respectively [ 3 ]. Aiming at decoupling the adversely interdependent TE parameters { α , σ , κ } and thus the high zT , the band engineering [ 4 , 5 , 6 ] and microstructure engineering [ 7 , 8 , 9 , 10 , 11 ] are implemented to enhance the power factor PF = σα 2 and reduce the κ L , simultaneously. For TE materials undergoing phase transition, implementing phase engineering can also expand the phase favorable to thermoelectric and restrain the negative phase [ 12 , 13 ].…”