New insights into the growth mechanism of hierarchical architectures of PbTe synthesized through a triethanolamine-assisted solvothermal method and their shape-dependent electrical transport properties

Abstract

In this article, a triethanolamine (TEA)-assisted solvothermal method has been devised to synthesize PbTe hierarchical nanostructures on a large scale with various shapes, including octapodal dendrites with a spiral step hollow cubic center, hopper structures, and nanowires with branched nanorods, by tuning the amount of KOH and the volume ratio of the solvent. Systematic variation of the kinetic factors, including the reaction temperature, the duration time, the ratio of source materials, and the KOH concentration, reveals that the morphology depends mainly on the supersaturation degree of the free Pb 2+ ions released from Pb(TEA) 22+ under elevated temperature. The formation processes of the PbTe octapodal dendrites with a spiral step cubic center and nanowires with branched nanorods were believed to follow the screw dislocation-driven growth and in situ template and secondary nucleation route, according to the extensive experimental data. In addition, the electrical transport properties of the bulk samples consisting of octapodal dendrites, hopper structures, and nanowires with branched nanorods were measured to investigate the possible impact of the morphology on the electrical transport properties. The unusual electrical behaviors with temperature are attributed to charge carrier scattering at grain boundaries.

Structure and Thermoelectric Properties of Spark Plasma Sintered Ultrathin PbTe Nanowires

“…Meanwhile, considerable effort has been made toward creating high ZT PbTe with nanofeatures using low-temperature solution-phase synthesis methods. Common synthesis techniques include hydrothermal synthesis, − reaction of a Pb-oleate precursor with triocytlphosphine-tellurium in organic solvent, − and others. − Generally, dried nanopowder is compressed by spark plasma sintering (SPS) or by hot pressing to obtain millimeter-sized discs for thermoelectric property measurements.…”

Self-sacrifice Te template synthesis of new phase PbmSb2nTem+3n nanorods via Pb2+/Sb3+ synergistic effect

“…Some examples from the literature reported that the morphology and size of PbTe crystals are sensitive to the synthetic temperature. For example, Wang's research group obtained different shapes of PbTe including tiny particles, nanocubes, nanocubes with spiral steps and dendrites with spiral step hollow cubic centers via ranging the temperature from 100 C to 160 C. 24 In our case, distinct morphologies can be fabricated at 120 C, 140 C and 200 C, respectively, without changing any other experimental conditions (Fig. 6).…”

“…Bulk lead telluride (PbTe), due to its narrow band gaps (0.32 eV) and face-centered cubic structure, has been applied widely in a number of elds such as photovoltaics, IR photoelectrics and thermoelectrics. 17,18 In recent years, various morphologies of PbTe including quantum dots, 19 nanolms, 18 nanosheets by self-assembly from nanoparticles, 20 porous microstructures, 21 nanocubes 17,22 hierarchical nanostructures [23][24][25] and nanowires/nanorods 26 have been fabricated via multiple varied methods. On the other hand, alloying lead chalcogenides with a small amount of other semiconductor compounds for ternary or multinary compounds can increase the gure of merit by tuning the electrical transportant properties and the lattice thermal conductivity.…”

The use of castor oil and ricinoleic acid in lead chalcogenide nanocrystal synthesis

“…Lead chalcogenides are direct bandgap IV-VI semiconductors, which exhibit unusual physical properties such as an anomalous order of bandgaps, high carrier mobility, high dielectric constant, optical photosensitivity near infrared, strong quantum size effect, multiple exciton generation, and positive temperature coefficients [6][7][8][9]. Nanostructured lead chalcogenides are excellent materials for increasing thermoelectric efficiency [10][11][12][13], photovoltaic devices [6], biological imaging [14], and infrared detectors [15]. The wide applications of lead chalcogenides (PbS, PbSe, and PbTe NCs) are because of their ability to produce multiple excitons upon absorbing a single proton of appropriate energy, a process known as multiple exciton generation (MEG).…”