Photovoltaic materials: Cu₂ZnSnS₄ (CZTS) nanocrystals synthesized via industrially scalable, green, one‐step mechanochemical process

Abstract

The present study demonstrates a scalable approach towards the pure Cu2ZnSnS4 (CZTS) phase starting from microsized Cu, Zn, Sn, and S mixture or a combination of nanosized CuS, SnS plus microsized Zn and S. A set of mechanochemical reactions was carried out in an industrial vibratory mill. The pure CZTS phase was obtained after 360 minutes of milling with an average crystallite size of 15 nm for both mixtures. The kinetics of CZTS formation was investigated following the X‐ray diffractometry (XRD) patterns of the reaction mixtures milled for various times. The morphology of particles and their elemental composition was studied by scanning electron microscopy (SEM)/transmission electron spectroscopy (TEM) and EDX analysis. Photoelectron spectroscopy (XPS) analysis showed the presence of Cu+, Zn2+, Sn4+, and S2− species on the surface of CZTS with only minor oxidation. Thermal stability of the synthesized materials was followed by thermogravimetric analysis. Based on UV‐VIS measurements, the calculated bandgap Eg = 1.44 to 1.50 eV of the synthesized CZTS samples is acceptable for photovoltaic application. Moreover, the applied mechanochemical approach can produce 100 to 500 g of CZTS in a batch mode experiment that is 10 to 50 times higher amount as the throughput of laboratory planetary mills. Hypothetically, in the applied industrial eccentric vibratory mill, the amount can be increased up to 50 kg per one batch.

Comparative Study of Nanostructured CuSe Semiconductor Synthesized in a Planetary and Vibratory Mill

“…Different types of mill, producing a different nature and intensity of mechanical energy, which is applied to the mechanochemical synthesis, can determine its course, and the formation of centers responsible for a solid-state reaction [ 33 ]. The products of the same mechanochemical reaction obtained using different types of mills may differ in crystal structure, morphology, and properties, as has already been demonstrated in a couple of papers by our research group [ 27 , 34 ]. The planetary and vibratory mills differ in several aspects of the working regime.…”

“…Higher content of the orthorhombic phase, in the case of planetary ball milling, most probably points to a more pronounced first-order transition of α-CuSe to β-CuSe. This is most probably a result of the fact that the local temperatures in the planetary ball mill are higher than in the case of the vibratory mill, as more pronounced reaction progress has been found when comparing the two types of mills in the past [ 27 , 34 ].…”

“…Several metal selenides, together with binary and ternary copper sulfides were mechanochemically synthesized using a scalable eccentric vibratory mill, and in the case of CuS commercial production was also verified [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Different types of mill, producing a different nature and intensity of mechanical energy, which is applied to the mechanochemical synthesis, can determine its course, and the formation of centers responsible for a solid-state reaction [ 33 ].…”

Kesterite Cu 2 ZnSnS 4 thin films synthesized utilizing electrodeposition: Influence of metal doping on the properties

“…37 The Zn2p peaks detected at 1042.81 and 1020.31 eV had an orbit of 22.49 EV indicative of the oxidation states of Zn 2+.38 The peaks at 494.95 eV and 486.55 eV corresponded to the binding energy of Sn (IV),with a spike at 8.4 eV which is nearly compatible with that of Sn 4+ in CZTS alloy films. 39 The S 2p peaks displayed peaks at 167.16 and 164.08 eV with a spike at 3.08 eV, demonstrating the presence of sulfur state in the CZTS. 40,41 The XPS affirms the oxidation states chemical composition needed for CZTS structure in the anticipated stoichiometric ratio.…”

Sustainable and rapid preparation of nanosized Fe/Ni-pentlandite particles by mechanochemistry

“…In general, mechanochemical reactions proceed through the transfer of kinetic energy from impacting balls to powdery particles and allow for a rapid and precise synthesis of nanosized particles (NSPs) in a single step. 20,21 The attractiveness for such an approach for industrial applications is further strenghtened by two major advantages: 22,23 First, large scale tools for mechanochemistry such as extruders and vibratory mills are wellestablished and allow for a reliable scaleability of the process. Second, sustainable reaction conditions can be assured by avoiding complementary additives or organic solvents.…”