Cation-Exchange Synthesis of Lead Bismuth Sulfide Quantum Dots and Nanorods for Thermoelectric Applications

Abstract

Cation-exchange-induced phase transformations have recently been employed for the synthesis of a variety of nanomaterials. In this study, we induced a cation-exchange reaction by adding Bi-oleate to PbS quantum dots (QDs) and synthesized uniform Pb1–x Bi x S y QDs and nanorods (NRs) with a diameter of approximately 3 nm and length of 40 nm (aspect ratio 1:5), respectively. Colloidal QDs are promising materials for thermoelectric applications owing to their simple production process, easy dimensional control, low thermal conductivity, and high Seebeck coefficient. We studied the thermoelectric properties of Pb1–x Bi x S y QDs and NRs synthesized through cation exchange. The Pb1–x Bi x S y NRs exhibited high values of the Seebeck coefficient (−181.31 μV/K at 450 K) and power factor (3.14 μW/cm·K2 at 650 K), and the electrical conductivity dramatically increased from 0.91 to 14.88 S/cm with an increase in temperature.

Nanocrystal Heterostructures Based On Halide Perovskites and Lead–Bismuth Chalcogenides

“…Assuming a small underestimation of the sulfur content due to the overlap of the characteristic S K- and Pb M-lines, the closest matching composition is galenobismuthite with a formal composition of 14% Pb, 29% Bi, and 57% S. Furthermore, some interchangeability between the Pb and Bi cations is expected, allowing for a variability in composition, as these structures also form homologous series. Nanorods of very similar dimensions and composition to the ones found in this work (Pb: 45% Bi: 55% vs here Pb: 40% Bi: 60%) have been investigated earlier for their thermoelectric properties and were assigned to lillianite . A comparison of the diffraction pattern of the heterostructures to simulated patterns of both lillianite and galenobismuthite are shown in Figure D.…”

“…Nanorods of very similar dimensions and composition to the ones found in this work (Pb: 45% Bi: 55% vs here Pb: 40% Bi: 60%) have been investigated earlier for their thermoelectric properties and were assigned to lillianite. 40 A comparison of the diffraction pattern of the heterostructures to simulated patterns of both lillianite and galenobismuthite are shown in Figure 1D. Due to the uncertainty in assigning a crystal phase, here they will still be referred to simply as Pb x Bi y S z or chalcogenide domains.…”

“…With both lead and bismuth being isoelectronic and active species in the reaction mixture, our synthesis gives access to compounds within the ternary PbS–Bi 2 S 3 system for the domain grown on the perovskite seed. Compounds in this PbS–Bi 2 S 3 system have been investigated as NCs and in bulk for their thermoelectric properties, , but the variation of the composition might also allow a facile tuning of the band gap. , In essence, the introduction of bismuth results in the formation of NC heterostructures made of two domains: a prismatic CsPbBr 3 perovskite domain and an elongated Pb x Bi y S z chalcogenide domain. These NC heterostructures are investigated by advanced electron microscopy to identify their three-dimensional shape, and the progress of the reaction is followed by in situ and ex situ experiments to investigate their formation.…”

Realizing High Electrical Conductivity in Chlorine-Doped Bi2S3 Thermoelectric Thin Films via Air Plasma Treatment

“…Electrical conductivity depends on the year for Bi 2 S 3 -based thin films, which were prepared for different methods (CBD refers to chemical bath deposition; SP refers to spray pyrolysis; CD refers to chemical drop method; ALD refers to atomic layer deposition; EBP refers to electron beam patterned; SILAR refers to successive ionic layer adsorption and reaction; SAMs refers to self-assembled monolayers; NRs refers to nanorods, NWs refers to nanowires, The literature points correspond to data in refs , , − , , , and − .…”

“…Various strategies have been reported to enhance the electrical conductivity of bulk Bi 2 S 3 materials by increasing the carrier concentration ( n ), such as doping with Cu, BiCl 3 , , CuBr 2 , PbBr 2 , SbCl 3 , and halogen acid, etc. However, there is a lack of studies focusing on improving the conductivity of Bi 2 S 3 TE thin films for IoT sensors, including hydrogen sensors, temperature piezoelectric sensors, and wearable devices. ,− These applications involve low-power processing and communication equipment, and a high electrical conductivity can effectively reduce power consumption and extend the service life of the devices. Therefore, it is crucial to explore new strategies to improve the electrical conductivity of Bi 2 S 3 TE thin films and to facilitate their application in relevant IoT sensor applications …”