Report on cascade energy relaxation from PVP to Tb3+:Bi2SiO5 nanophosphor through salicylic acid in composite polymeric film

Abstract The present article reports structural and spectroscopic properties of Tb:Bi2SiO5 nanophosphors dispersed in Polyvinylpyrrolidone polymer film, in presence of Salicylic acid (SA) molecule, which acts as a sensitizer. Detailed structural and spectroscopic characterizations were carried out using X-ray diffraction patterns, Scanning Electron Microscope, Fourier Transform Infrared and Excitation and photoluminescence techniques. The mean crystallite size of Tb3+:Bi2SiO5 nanophosphor and Tb3+:Bi2SiO5 in Polyvinylpyrrolidone polymer composite was estimated ∼22 nm and ∼28 nm, respectively. We have report atleast two times enhancement in Tb3+ ions emission intensity due to the efficient energy transfer from salicylic acid molecule to Tb ions. In addition to energy transfer from salicylic acid, the Polyvinylpyrrolidone polymeric host was also reported to serve as a sensitizer for SA molecule and Tb3+ ions through a cascade energy relaxation process while exciting with 248 nm photons. On 248 nm photon excitation, atleast five improvements in Tb3+ ion emission intensity are reported. Presence of SA molecule facilitates precise colour tuning as obvious from the CIE coordinates.