A mild hydrothermal route to synthesis of CZTS nanoparticle inks for solar cell applications

Abstract

AbstractCu2ZnSnS4 (CZTS) is a promising thin film absorber material for low cost solar cell applications. Its absorption coefficient (∼ 104 cm‐1), crystal structure and band gap energies (∼1.5 eV) are similar to those of Cu(In,Ga)Se2 (CIGS), one of the most studied and flourishing thin film solar cell absorber materials. However, unlike CIGS, which requires the expensive and rare elements; In and Ga, CZTS is composed of reasonably priced and abundant elements like Zn and Sn. In the present investigation, kesterite CZTS nanoparticle inks were obtained by a hydrothermal process using Cu, Zn and Sn chlorides, and Na sulfide. The synthesized CZTS nanoparticles were characterized using optical absorption, X‐ray powder diffraction (XRD), energy dispersive spectroscopy (EDS), micro‐Raman spectroscopy, high‐resolution transmission electron microscopy (HRTEM), and X‐ray photoelectron spectroscopy (XPS). The optical and morphological properties demonstrated that the prepared nanoparticles have strong absorption in 300−550 nm range with band gap energy of 1.55 eV with an average particle size of 20 nm. The X‐ray and micro‐Raman analysis revealed that the synthesized CZTS nanoparticles have the phase pure kesterite structure. We believe that our synthetic method will be helpful for low‐cost and efficient thin film photovoltaic technology. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)