Facile synthesis of UV-white light emission ZnSe/ZnS:Mn core/(doped) shell nanocrystals in aqueous phase

Abstract

ZnSe/ZnS:Mn core/(doped) shell and ZnSe/ZnS: Mn/ZnS core/(doped) shell/shell nanocrystals (NCs) that emit white light were synthesized in aqueous media. White light emission of as-prepared NCs is a result of combined emission of blue light (emission from band gap of ZnSe core) and yellow/orange light (T-4(1)-(6)A(1) emission from Mn2+ ions doped in ZnS of the first shell). Especially, the green emission generated from surface defects was found as a key factor that affects the photoluminescence quantum yields of core/(doped) shell and core/(doped) shell/shell NCs. Photoluminescence from the Mn: ZnS d-dots was easily tuned from 580-600 nm by regulating feeding molar ratio [Zn]/[Mn]. Under the sufficiently low Mn2+ dopant concentration, ZnSe/ZnS: Mn and ZnSe/ZnS: Mn/ZnS NCs emit white light with a quantum yield about 27.6% and 20.5%, respectively.