Projekteja vuodessa
Abstrakti
We demonstrate a ptype to ntype conductivity transition for thermoelectric CoSbS achieved by precisely controlling the sulfur vapor pressure during the sample synthesis. The pn transition is experimentally confirmed by both the Seebeck coefficient and the Hall effect measurements. From the crystal structure refinements, the increase in the sulfur vapor pressure in the synthesis is weakly but steadily reflected in the occupancy factor of sulfur in the CoSbS lattice, while the pn transition is seen as a peak in all the three lattice parameters, a, b, and c. Computationally, the situation could be simulated with first principle DFT calculations on compressed CoSbS. Without compression, DFT presents CoSbS as a ptype semiconductor with an indirect bandgap of 0.38 eV, while the pressure application results in an ntype semiconductor with decreased lattice parameters but the same indirect bandgap as in the uncompressed case. Experimentally, the thermal conductivity is strongly enhanced for sulfurdeficient samples, which could be due to larger phonon mean free paths. The sulfur loading significantly enhances the electrical conductivity while moderately decreasing the Seebeck coefficient such that the overall power factor is improved by a factor of 9 for the ntype sample and by a factor of 6 for the ptype sample, owing to the increased charge carrier density, although the performance is still relatively low. Thus, this study highlights CoSbS as a promising building block for thermoelectric devices based on its bipolar semiconductor nature with the possibility for both ptype and ntype doping with enhanced power factor.
Alkuperäiskieli  Englanti 

Artikkeli  091104 
Sivumäärä  8 
Julkaisu  APL Materials 
Vuosikerta  10 
Numero  9 
DOI  pysyväislinkit  
Tila  Julkaistu  13 syysk. 2022 
OKMjulkaisutyyppi  A1 Julkaistu artikkeli, soviteltu 
Sormenjälki
Sukella tutkimusaiheisiin 'ptype to ntype conductivity transition in thermoelectric CoSbS'. Ne muodostavat yhdessä ainutlaatuisen sormenjäljen.Projektit
 1 Päättynyt

PREIN: Fotoniikan Tutkimus ja Innovaatio
01/01/2019 → 31/12/2022
Projekti: Academy of Finland: Other research funding
Laitteet

Raakaaineiden tutkimusinfrastruktuuri
Maarit Karppinen (Manager)
Kemian tekniikan korkeakouluLaitteistot/tilat: Facility