Quantum yield measurement of phosphors using an indigenous integrating sphere

This paper reports the measurement of photoluminescence quantum yield (PLQY) of well-known tri-color phosphors, namely Y₂O₃:Eu³⁺ (red), YVO4:Eu³⁺, YBO3:Eu³⁺, BaMgAl10O17:Eu2+ (blue), and LaBaB₉O₁₆:Tb³⁺ (green), using an indigenously designed integrating sphere coupled with a fluorescence spectrophotometer. The system operates on the principle of collecting the total emitted and scattered radiation from the sample within the integrating sphere and determining the quantum yield by comparing the emission intensity with the incident excitation intensity. The optimum dopant concentrations for all the host materials were achieved using the solid-state diffusion method. The photoluminescence (PL) excitation and emission spectra of the synthesized phosphors were found to be in good agreement with those reported in the literature, confirming the reliability of the prepared samples. The quantum yield values measured using the developed setup were compared with those obtained from a standard FLS-1000 spectrometer (Edinburgh Instruments, UK), demonstrating close agreement and validating the performance of the indigenously designed system. The optical geometry of the Hitachi F-7000 spectrophotometer was modified such that the excitation beam enters the integrating sphere through one port, interacts with the sample, and both the reflected excitation light and the emitted luminescence are sequentially recorded by the detector.