1.Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore ;2.Department of Electrical and Electronic Engineering, Universiti Tunku Abdul Rahman, Sungai Long Campus, Jalan Sungai Long, Bandar Sungai Long, Cheras, Kajang, 43000, Selangor, Malaysia ;3.Institute of Materials Research Engineering, A*Star (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, Singapore, 138634, Singapore ;4.Center for Advanced 2D Materials and Graphene Research Center, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore ;
Abstract:
Recovered carbon black (rCB), a very economical and abundance source of material, is transformed into dazzling multicolour fluorescence and visual display for the first time by way of a scanning focused laser treatment. This laser-initiated process is both straightforward and versatile, catering to both micro- and macro-scopic patterning with the sample in ambient or helium environment. The observed phenomenon is attributed to both chemical and structural induced colouration of rCB powder. Chemically, carbon infusion of oxidised metal occurs when photothermal reaction takes place in ambient. After laser modification with the sample in helium environment, the powder not only fluoresces due to sulphur impurities, control annealing of these powders results in formation of periodic arrangements of carbon nanoparticles. The periodicity of these arrangement falls within the range of visible wavelength, hence contributing to the visually observable rainbow coloured rCB flakes. The patterned sample is also transferrable using PDMS stamps. This in turn broadens the application of this material in flexible electronic devices/displays. Photocurrent measurements show most significant enhancement under yellow light illumination. Furthermore, in the presence of an applied potential, the fluorescence detected from the sample can easily be switched off. All in all, we present a simple process to add multiple functionalities to a material that is both inexpensive and sustainable.