Stable fluorescent CdS:Cu QDs and their hybridization with carbon polymer dots for white light emission

Abstract

A simply-processed, stable colloidal white light emission, obtained by hybridizing the orange emitting copper doped CdS (CdS:Cu) and cyan emitting carbon polymer dots (CPDs) as a donor–acceptor pair is described. The chromaticity colour coordinates of the obtained white light were (0.32, 0.33). To achieve this, we formulated a new approach for synthesizing stable CdS:Cu QDs in non-coordinating mixed solvents, without using additional capping agents. The CPDs were synthesized by the controlled decomposition of branched polyethylenimine, followed by purification. Finally, proportionate amounts of orange emitting CdS:Cu and CPD dispersion were used to produce white light emission. We further stabilised the colloidal white light emission in organically modified SiO₂ (ORMOSIL) sol, which can be used as fluorescent paint, and to deposit durable coatings on glass substrates. The coated films show very good PL stability when stored under ambient conditions and under UV (365 nm) light.