Silica coating of indium phosphide nanoparticles by a sol–gel method and their photobleaching properties

Abstract

Indium phosphide (InP) nanoparticles face at problems such as aggregation and photobleaching, and formation of core–shell structure is promising to solve the problems. This paper examined the method of coating the InP nanoparticles with silica via sol–gel reaction in reverse micelles. Fabrication of silica-coated InP (InP/SiO2) nanoparticles was performed by using the reverse microemulsion method, in which the sol–gel reaction of tetraethyl orthosilicate and water with ammonia is performed in reverse micelles composed of polyoxyethylene (5) nonylphenylether, branched in cyclohexane containing InP nanoparticles. The InP nanoparticles did not aggregate because of physical barriers of silica shells. The silica coating controlled photobleaching of the InP nanoparticles; the colloid solution of InP/SiO2 nanoparticles emitted more stable fluorescence than that of the shell-free InP nanoparticles, even after the InP/SiO2 nanoparticles were placed in a dark box in an atmosphere set to room temperature.