Fabrication of white light emitting nanophosphors with high luminous efficacy is an urgent need for the next generation lighting industry and display systems. While rear-earth ions have been frequently utilized as dopants to fabricate semiconducting and dielectric nanophosphors, limited abundance of rare earth elements on our planet demands a search for suitable alternatives. Here we report the fabrication of ZnS nanoparticles co-doped with Co²⁺ and Mn²⁺ transition metal ions which manifest intense near-white light emission under ultraviolet (UV) excitation.

While the nanophosphors could be fabricated through a simple low-temperature two-step chemical process, both the colour and intensity of their emission can be tuned just by varying the molar concentration of the two dopant ions. The variation of emission colour and its intensity in the nanophosphors due to dopant ion concentration has been explained considering inter-band energy transfer from Mn²⁺ ions to Co²⁺ ions and creation of deep level defect states in the host nanocrystals.

The synthesis process utilized in the present work opens up the possibility of fabricating low cost, emission tuned, rare-earth free nanophosphors for developing high efficiency light-emitting devices.