Alteration of Mn exchange coupling by oxygen interstitials in ZnO:Mn thin films

► Oxygen rich ZnO:Mn thin films deposition by simple spin coating technique. ► Incorporation of tetrahedral Mn2+ ions at lattice sites Zn2+ ions without any impurity phase formation. ► Enhanced optical transparency and optical band gap with increasing Mn doping concentration. ► Deep level emissions in yellow spectral region confirmed the presence of oxygen interstitials. ► Origin of ferromagnetism in Mn-defect pair exchange coupling with oxygen interstitials.