A cost-effective quantum yield measurement setup for upconverting nanoparticles

Generally, emission quantum yield values of upconverting nanoparticles are not reported, despite its importance for characterizing the material's performance, because the measurements require quite expensive setups (a single photomultiplier operating in a broad spectral regions from the visible to the near-infrared) and laborious procedures (spectral mismatch correction when two photomultipliers are used). Here we describe the implementation of a simple and cost-effective quantum yield measurement setup using a commercial integrating sphere-based spectrometer operating in the visible spectral range and a power meter to determine the incident number of photons. First, we validate the experimental methodology using well-known down-shifting standard phosphors (sodium salicylate and perylene). Then, we use the developed setup in an illustrative example of upconverting nanoparticles, SrF2:Yb3+/Er3+(20/2%), to quantify their emission quantum yield values in powder (0.0057±0.0002 at 388 W cm−2) and water suspension (0.0028±0.0001 at 395 W cm−2).