Fabrication of nanostructured copper indium diselenide (CIS) thin films by electrohydrodynamic atomization technique

In this article, we report a non-vacuum electrohydrodynamic atomization (EHDA) technique for deposition of CulnSe2 (CIS) thin films. The CIS ink has been prepared with three different concentrations (7.5 wt.%, 12.5 wt.% and 15 wt.%) by using suitable solvent mixture (ethanol:terpineol as 1:1 molar ratio) with surfactant to achieve a stable dispersions. The important physical parameters for achieving homogeneous with non-agglomerated CIS layers through EHDA technique are investigated in detail. The X-ray diffraction pattern confirms the crystalline structure of CIS layers oriented in the chalcopyrite phase. The film uniformity has been investigated by field emission scanning electron microscopy. Different thickness of CIS layers has been achieved by varying the concentration of CIS particles in the precursor ink solution. The optical properties of CIS layers show the two optical band gaps in UV-visible and near infra-red (NIR) region with band gap of about 2.67-2.49 eV and 1.34-1.29 eV respectively. The energy band gap of CIS thin films have been decreased with the increase of film thickness. The X-ray photoelectron spectra confirmed presence of binding energy corresponding to CulnSe2. The electrical study observed the sheet resistivity 76-33 Omega cm with respect to film thickness.