The modification of the band gaps in semiconductor can result in significant enhanced performance, providing new applications for electronic, optoelectronic, and photocatalytic devices. Here we report a facile, cost-effective, and green method to synthesize the Fe:ZnSe nanocrystals with tunable band gap and high emission, and only low cost and environmentally friendly reagent are used, benefiting the practical applications. The synthesized Fe:ZnSe nanocrystal belongs to the zinc blende structure, and the as-synthesized Fe:ZnSe nanocrystal is spherical-shaped and exhibits nearly monodisperse size distribution, as confirmed by the transmission electron microscopy. Effects of different reaction times on the optical properties of the obtained nanocrystals were discussed in detail. Emission properties were controlled at 414-441 nm by tailoring their size, and the blue shift of the absorption edges of Fe:ZnSe samples could be attributed to the quantum confinement within the nanocrystals. More interestingly, the band gap of these as-synthesized nanocrystals can be tuned in the broad range of 3.37-3.10 eV by changing the reaction time. These results show that the new synthetic method of this work provides a new band gap engineering scheme for doped semiconductor nanocrystals and offers the opportunities for the design of ligand-stabilized semiconductor nanocrystals with tunable size and optical properties. (C) 2014 Elsevier B.V. All rights reserved.