We report a continuous-flow microreaction synthesis of ZnSe quantum dots (QDs) which are controllable in their emission from blue to white light. The emission of ZnSe QDs exhibits quantum confinement effect, which is adjusted by the flow rate of precursor solution. The ZnSe QDs' high concentration solution shows red-shifted emission in the blue region and strongly enhanced green-yellow emission from deep levels due to the inter-QD energy transfer, thereby exhibiting white color with CIE color coordinates of (0.33, 0.33). The red-shifted band-edge emission with longer decay time in the dense solution confirms that the energy is transferred efficiently between QDs. (c) 2013 The Electrochemical Society. All rights reserved.