Effective Yellow Y ₃ Al ₅ O ₁₂ :Ce ³⁺ Nanophosphor for Light‐Emitting Diode and Photovoltaic Cell as a Downconverter

Yellow Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce) nanophosphors are prepared through a coprecipitation method. The optimal one shows a single phase, with a particle size of less than 50 nm and the broad photoluminescence (PL) spectra with a maximum peak at 560 nm. Its best quantum efficiency of 65% is achieved, and its lumen maintenance at 200 °C approaches 76%, which is comparable with that of a commercial bulk phosphor. Its applications to white light‐emitting diode (LED) and photovoltaic cell as downconverter are demonstrated. The white LED with the nanophosphor shows higher color rendering index (79) than that of the bulk (74). The significant photovoltaic efficiency is enhanced from 17.2% to 19.1%.