Instantaneous preparation of CuIn(S1 − x, Sex)2 films by means of sparks using microwave irradiation

► CuIn(S1 − x,Sex)2 films for flexible solar cells were directly prepared on Ti foils. ► Elemental In, Cu, S, Se particle precursors were reacted using microwave irradiation. ► The lattice increased in proportion to the S/ (S + Se) ratio satisfying Vegard's law. ► The synthesized CuInSe2 crystals exhibit chalcopyrite-structure with high crystallinity.