Photoluminescence study of pure and Li-doped ZnO thin films grown by sol-gel technique

► Photoluminescence of Li-doped ZnO depends largely on annealing atmosphere. ► Warm-white photoluminescence is obtained for Li-doped ZnO annealed in He. ► This photoluminescence illustrates its promising application as white phosphor. ► Both substitutional and interstitial lithium exist in ZnO matrix. ► Visible emissions of ZnO are tuned indirectly by extrinsic lithium.