Deposition and characterization of Cu(In,Ga)Se2 thin films from the ink of sonochemically prepared CIGSe nanoparticles

CuIn1-xGaxSe2 (CIGSe) nanoparticles were synthesized via a sonochemical method at different Ga content (x = 0.15, 0.30 and 0.45) and dispersed in a low toxic isobutanol to form the nanoparticle-ink. Thin films of CIGSe were grown by a facile, non-vacuum and inexpensive “nanoparticle-ink based air-spray coating” method. Effects of Ga-content and annealing time on the physical properties of CIGSe thin films were investigated. The elemental composition, crystalline structure, surface morphology and optical properties of the films were explored by various characterization methods. XRD studies of as-synthesized films showed a tetragonal structure with (112) orientation. After annealing, the CIGSe films showed an improvement in the intensity ratio of I(220)/I(112) for the annealing time of 60 min. The morphological studies of annealed CIGSe films showed plank-like larger grains of size ∼1-2 µm. The films deposited at different gallium content, x = 0.15, 0.30 and 0.45 showed PL peak maxima at 954, 1049 and 1168 nm, respectively. The present method is capable of producing CIGSe absorbers by a greener route in large scales at lower cost.