CIGS absorber layer by single-step non-vacuum intense pulsed light treatment of inkjet-printed film

Non-vacuum processes are of great interest for development of low-cost chalcopyrite-based photovoltaic technologies. Apart from the expensive vacuum-based routes that are widely adopted, another negative feature of the popularly employed methods is the need for selenization treatment, which significantly impacts the microstructure of the absorber layer and, in turn, also determines the performance of the device. A novel process for preparation of Cu(In_0.7Ga_0.3)Se₂ (CIGS) films from an ink constituted of CIGS nanoparticles utilizing a convenient intense pulsed light (IPL) treatment is investigated in the present study. Initially, a thorough optimization of ink formulation variables was carried out in order to make the CIGS ink suitable for ink jet printing. The home-made CIGS ink, comprising CIGS nanoparticles with appropriate additives, was then successfully deposited with a print head having 256 nozzles on Mo coated soda lime glass substrate. Subsequently, IPL was used to treat the printed CIGS ink. Post IPL treatment, a CIGS film retaining the chalcopyrite structure even after melting and recrystallization, with no secondary phase formation, was realized. The phase constitution, thickness and morphology of prepared films were determined using X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF) and field emission scanning electron microscopy (FESEM). The above non-vacuum, room temperature process not requiring any selenization treatment can have important implications in realization of cost-effective CIGS absorber layers.