Publications by authors named "Shaoping Zhan"
The relative impact of electronic instability and quantum confinement on lattice dynamics and transport properties remains elusive. Here, we demonstrate that the influence of lone-pair electrons (LPEs) expression on phonon dissipation surpasses that of dimensional reduction using a quasi-low-dimensional Pb-Sn-S-Se system as a prototype. We experimentally observe that quasi-one-dimensional (1D) PbSnS exhibits higher thermal transport than quasi-two-dimensional (2D) PbSnS, attributed to the loss of LPEs.
View Article and Find Full Text PDFThe scarcity of tellurium (Te) poses significant challenges to the widespread application of BiTe-based thermoelectric systems. In this work, we investigated the potential of Te-free PbSe for thermoelectric applications by optimizing carrier mobility through crystal growth and a two-step strategy of light alloying and doping. First, Cd alloying was employed to reduce the lattice thermal conductivity () of n-type PbSe through the off-center effect while preserving carrier mobility.
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- Optimizing both n-type and p-type thermoelectric materials like PbSnS is crucial for better device performance, as they exhibit unique transport characteristics.
- P-type PbSnS is enhanced through techniques like Na doping and Se alloying, showing different properties than n-type versions which utilize Cl doping.
- The analysis reveals that the efficiency of resistance to doping varies between n-type and p-type due to differences in their charge density distributions and structural characteristics.
Article Synopsis
- Thermoelectrics can efficiently recover waste heat and cool electronics, but their use is limited due to the shortage of BiTe materials.
- Researchers developed a low-cost, earth-abundant PbS compound that achieved a record-high ZT of 0.64 and has impressive cooling capabilities with a temperature difference of ~36.9 K.
- The new n-type PbS material also shows about 8% efficiency in power generation, highlighting its potential as a sustainable alternative to BiTe in thermoelectric applications.
The scarcity of Te hampers the widespread use of BiTe-based thermoelectric modules. Here, the thermoelectric module potential of PbSe is investigated by improving its carrier mobility. Initially, large PbSe crystals are grown with the temperature gradient method to mitigate grain boundary effects on carrier transport.
View Article and Find Full Text PDFThe room-temperature thermoelectric performance of materials underpins their thermoelectric cooling ability. Carrier mobility plays a significant role in the electronic transport property of materials, especially near room temperature, which can be optimized by proper composition control and growing crystals. Here, we grow Pb-compensated AgPbSbTe crystals using a vertical Bridgman method.
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- High carrier mobility is essential for better thermoelectric performance, but traditional doping methods can reduce it instead of improving it.
- This study presents a new approach to enhance carrier mobility in n-type PbTe by manipulating defects, specifically reducing intrinsic Pb vacancies and using excess Ag and iodine for further optimization.
- The result is significantly increased carrier mobility—up to ∼7300 cm V s at room temperature—and improved thermoelectric performance across a wide temperature range, demonstrating that precise defect tuning can dramatically enhance material properties.
Article Synopsis
- - Recent advancements in p-type SnS thermoelectric materials have been hindered by a lack of progress in n-type materials, which are crucial for device construction.
- - Researchers have created n-type PbSnS through alloying with lead, achieving a promising maximum ZT (figure of merit) of ~1.2, thanks to improved power factors and very low thermal conductivity.
- - By optimizing carrier concentration through Cl doping and utilizing multiple conduction bands, the PbSnS shows potential for efficient power generation, with a maximum efficiency of ~2.7% in a single-leg thermoelectric device.
Realization of unpinned two-dimensional dirac states in antimony atomic layers.
Nat Commun
August 2022
Two-dimensional (2D) Dirac states with linear dispersion have been observed in graphene and on the surface of topological insulators. 2D Dirac states discovered so far are exclusively pinned at high-symmetry points of the Brillouin zone, for example, surface Dirac states at [Formula: see text] in topological insulators BiSe(Te) and Dirac cones at K and [Formula: see text] points in graphene. The low-energy dispersion of those Dirac states are isotropic due to the constraints of crystal symmetries.
View Article and Find Full Text PDFThermoelectric generators enable the conversion of waste heat to electricity, which is an effective way to alleviate the global energy crisis. However, the inefficiency of thermoelectric materials is the main obstacle for realizing their widespread applications and thus developing materials with high thermoelectric performance is urgent. Here we show that multiple valence bands and strong phonon scattering can be realized simultaneously in p-type PbSe through the incorporation of AgInSe.
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