Thermoelectric properties of hot pressed CZTS micro spheres synthesized by microwave method

Abstract

Microwave synthesis of Copper Zinc Tin Sulphide (CZTS) sphere like particles has been demonstrated. The structural and morphological properties of CZTS particles are characterized by XRD, SEM and Raman spectroscopy and subsequently thermoelectric properties are investigated. XRD results of prepared powder sample matches well with tetragonal crystal structure of CZTS bulk. No other impurity phase has been detected from the XRD analysis. Raman spectrum further confirms the formation of single phase CZTS with characteristics peak for CZTS at 334.1 cm-1. SEM studies reveal that the CZTS particles are spherical in shape with uniform sizes of ∼ 250-350 nm. Hot pressed CZTS system shows a power factor ∼21 µW/mK2 and ZT∼ 0.024 at 623 K. Significant enhancement in the Figure of merit for CZTS system is observed in comparison to reported nanostructures of the same system may be due to increased electrical conductivity.

Order–Disorder Transition in Kesterite Cu2ZnSnS4: Thermopower Enhancement via Electronic Band Structure Modification

“…13,33 Furthermore, it could explain the difference found in the literature for CZTS in the trends of Seebeck coefficient, especially where the order−disorder transition is not explicitly observed or identified. 6,7,9,10 ■ ASSOCIATED CONTENT * sı Supporting Information…”

“…Kesterite (CZTS) is a p -type chalcogenide material with reference formula Cu 2 ZnSnS 4 . It has long been studied as absorber in thin film photovoltaic devices, − and recently deemed promising as a potential thermoelectric material, − valued for its intrinsically low thermal conductivity and composition based on nontoxic, abundant and low-cost elements . In its ordered and low temperature form, kesterite is reported having a tetragonal I4̅ crystal structure, while it was recently proved that a cubic F4̅3m low-temperature polymorph can be obtained for samples made by high-energy ball-milling, as an effect of a high disorder state of the cations. , This appears to be a metastable phase, since it transitions to the tetragonal polymorph on heating, as the temperature activates a reordering of the cations .…”

Static and dynamic components of Debye–Waller coefficients in the novel cubic polymorph of low-temperature disordered Cu2ZnSnS4

“…For the same reasons of sustainability and safety, CZTS has also been explored as a possible thermoelectric (TE) material (Liu et al, 2009;Yang et al, 2012;Kosuga et al, 2015;Kumar et al, 2018;Sharma & Neeleshwar, 2018;Zheng et al, 2018;Nagaoka et al, 2018;Isotta et al, 2019aIsotta et al, ,b, 2020aIsotta et al, ,b, 2021aSharma et al, 2019Sharma et al, , 2020Jiang et al, 2020;Long et al, 2020;Bala ´z ˇet al, 2021). Given the large energy gap, CZTS shows an increasing performance with temperature, thus potentially appropriate for applications in the mid to high temperature range (600-800 K) (Kosuga et al, 2015).…”

Effect of the Order-Disorder Transition on the Seebeck Coefficient of Nanostructured Thermoelectric Cu2ZnSnS4

“…The performance is usually expressed through the figure of merit zT = S 2 T /( ρk ), where S, ρ, T , and k are, respectively, the Seebeck coefficient, electrical resistivity, absolute temperature, and thermal conductivity [3] although recently the thermoelectric quality factor β has been proposed, as it draws attention to the most fundamental material parameters to be improved ( β ∝ N v /( m* I k L ), with N v , band degeneracy, m* I , inertial effective mass along the conduction direction, and k L , lattice thermal conductivity) [4,5]. Kesterite (Cu 2 ZnSnS 4 , CZTS) is a direct band gap p-type semiconductor that has recently been studied as a thermoelectric material [6,7,8,9,10]. The interest arises from the low cost, easy availability and non-toxicity, in addition to its low thermal conductivity (from 2.95 W/(m K) at 300 K to 0.97 W/(m K) at 700 K [7]).…”