Demands for Photoluminescence Quantum Yield (PLQY)applications are growing, and one big area for the growth is in the Near Infrared (NIR) spectral region. NIR emission plays an important role in optical communications (optical signal generation and amplification), biomedical applications, development of efficient laser glasses, such as Nd3+ laser systems, solar energy concentrators, optoelectronics and many others. The overwhelming majority of these applications involve lanthanide ions, many of which emit in the NIR. PLQY measurements are critical in assessing optical efficiency and performance of devices based on such materials. This application note illustrates the use of the Fluorolog-QM-75-21 fluorescence system with an integrating sphere option for the determination of PLQY in the NIR spectral region for two different lanthanide-based materials.
All HORIBA spectrofluorometers equipped with integrating spheres are validated with two very specific standard samples, quinine sulfate and rhodamine, which are accepted PLQY reference materials in the scientific community. Instruments must pass the accepted PLQY values for these samples in the final QC process prior to shipment to a customer. The spectral correction curves used for detector wavelength correction and for PLQY are based on the method described below and they encompass the entire spectral range of the specific NIR detector selected with the instrument. Today there is no globally accepted NIR reference material for PLQY qualification, but we demonstrate below that the Fluorolog-QM is indeed an excellent choice for NIR PLQY measurements.