Near-infrared two-photon excited photoluminescence from Yb-doped CsPbClBr perovskite nanocrystals embedded into amphiphilic silica microspheres.

Nonlinear absorption of metal-halide perovskite nanocrystals (NCs) makes them an ideal candidate for applications which require multiphoton-excited photoluminescence. By doping perovskite NCs with lanthanides, their emission can be extended into the near-infrared (NIR) spectral region. We demonstrate how the combination of Yb doping and bandgap engineering of cesium lead halide perovskite NCs performed by anion exchange (from Cl to Br) leads to efficient and tunable emitters that operate under two-photon excitation in the NIR spectral region.