Microwave Synthesis of Thin Film Absorber Layer Nanopowders of Copper-Indium-Gallium-(di) Selenide and Copper-Zinc-Tin-Sulfide

Microwave irradiation is a fast, reliable and efficient technique for thermally driven chemical reactions used to produce various in-organic nano-powders. This paper reviews the microwave synthesis method for the preparation of size and composition defined nanopowders of copper-indium-gallium-(di)selenide (CIGS) and copper-zinc-tin-sulfide (CZTS) applicable for absorber layers in thin film solar cells. For CIGS synthesis, precursor mixtures consisting of metal acetylacetonates and selenium powder in oleylamine and for CZTS synthesis, metal chlorides and thiourea in ammonium hydroxide and deionized water were heated in microwave at 180-220°C for 20-60 minutes respectively. The resultant nanopowder was characterized and optimized for particle size by dynamic light scattering, phase by X-ray diffraction, morphology and elemental distribution by scanning electron microscopy and band-gap by UV-Vis-NIR spectroscopy. CIGS and CZTS inks, suitable for spin coating and ink-jet printing were prepared and thin films were deposited and characterized.