Rapid microwave synthesis of Cu ₂ ZnSnS ₄ nanocrystals for photovoltaic junctions

Abstract

Summary Copper zinc tin sulfide (CZTS) nanocrystal (NC) ink was prepared using thiourea as sulphur source by microwave assisted process. Thin films fabricated by doctor blading technique were then used to analyze the structure and morphology of the CZTS NCs. Variation in the properties of the NCs with varying Zn content in the precursor solution was studied. A Zn/Sn ratio of 1.4 with a Cu/(Sn + Zn) ratio of 0.8 in the starting solution was identified as an optimum compositional ratio to get good optoelectronic properties. Synthesis of CZTS NCs was done in ethylene glycol solvent and in a solvent which is a 1:1 mixture of isopropanol and poly ethylene glycol. The films developed from the latter ink showed better morphological and optoelectronic properties. CZTS thin films show absorption coefficient of the order of 104 cm−1 and optical band gap of 1.5 eV. The electrical resistivity was found to be 2.5 × 102 Ω/cm and hole mobility 0.051 cm2/ (Vs). Glass/FTO/CdS/CZTS multilayer structures were fabricated to form P‐N junctions. A knee voltage of 0.8 V from the I‐V characteristics of the PN junction indicates that a good Voc can be expected from a solar cell constructed with CZTS ink as absorber layer.

Effect of oleylamine on microwave synthesized Cu 2 ZnSnS 4 nanocrystals for photovoltaic junctions

“…A) . When the irradiation time was increased to 150 seconds, the initial nuclei combined to give pure quarternary Cu 2 ZnSnS 4 by a self assembly and Ostwald ripening process . Better phase purity was obtained at 750 W than at lower microwave powers as can be seen in the Raman spectra.…”

“…The latter solution was added drop by drop to the former to get the colourless precursor solution. Molarity of the precursors was in the ratio 1.92:1.4:1:12 as optimized in our previous work reported by Krishnan et al Under acidic conditions, thiourea reduces Cu 2+ to Cu + . It forms complexes with the metal cations: [Cu (TU)] + , [Sn (TU)] 2+ , and [Zn (TU)] 2+ .…”

“…It consumes less energy and time and gives larger quantity of phase pure CZTS NCs. Successful synthesis of phase pure CZTS NCs using this fast and simple method has been reported earlier using different solvents including ethylene glycol and ethylene diamine and with different precursors and sulfur sources …”

“…The objective of the present work is to improve the properties of the CZTS NCs synthesized by rapid microwave‐assisted method . Larger particle sizes were seen to give porous thin films.…”

Microwave‐mediated noncatalytic synthesis of ethyl levulinate: A green process for fuel additive production

“…The esterification process has been intensified using microwave irradiation (MW) . Microwaves are electromagnetic waves that deliver energy to reactants through relaxation or resonance .…”