Luminescence and luminescence quenching of K2Bi(PO4)(MoO4):Sm3+ phosphors for horticultural and general lighting applications

Abstract

The purpose of this study is to investigate the optical properties of Sm³⁺ doped K₂Bi(PO₄)(MoO₄) phosphors as possible candidates for application in light emitting diodes (LEDs) for horticultural and general lighting applications. Sm³⁺ doped phosphors with 0.5%, 1%, 2.5%, 5%, 10%, 25%, 50%, 75% and 100% Sm³⁺ have been prepared by solid state reaction method. The synthesized materials were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The room temperature (RT) reflection, excitation, and emission spectra, photoluminescence (PL) decay curves, as well as temperature dependent emission and excitation spectra and PL decay curves were measured and discussed. Moreover, quantum efficiencies, and lumen equivalents (LE) were determined and discussed. The prepared K₂Bi(PO₄)(MoO₄):Sm³⁺ phosphor samples show moderate quantum efficiency, high colour purity, and a high quenching temperature. These properties are required for phosphors if they are under consideration for application in LEDs and other areas. It was also shown, that the PL emission of the phosphor well matches the absorption of the main plant pigments thus making it a good candidate for horticultural lighting applications. Using this phosphor and a near-UV LED a phosphor-converted LED (pcLED) prototype, meeting the photophysiological needs of plants, was designed. Supplementing the prototype with a green or lime LED the colour rendering index and luminous efficacy of radiation of the prototype is greatly increased thus making it more efficient and pleasant for people present at the greenhouse.