Mn incorporation in CuInS2 chalcopyrites: Structure, magnetism and optical properties

► Up to 10% of the Cu/In sites is replaced with Mn in CuInS2. ► Mn prefers the In site under In-poor conditions for low-Mn-content samples. ► The oxidation states of Cu+, Mn2+ and In3+ are established. ► CuInS2:Mn is paramagnetic with short-range antiferromagnetic interactions. ► The bond alternation and p-d hybridization decrease the bandgap by ∼0.1 eV.