Quantum cutting-induced near-infrared luminescence of Yb and Er in a layer structured perovskite film.

Quantum cutting is an attractive optical phenomenon where one high-energy photon is converted into two low-energy photons, resulting in photoluminescence quantum yields (PLQYs) above 100%. In this report, we demonstrate a novel approach to enhance the quantum cutting energy transfer from an all-inorganic perovskite (CsPbCl) to ytterbium (Yb) and erbium (Er) ions as near-infrared (NIR) emitters by using the highly orientated crystalline film. Yb ions are fixed in the neighborhood of the CsPbCl lattice by preparing a one-to-one layer arrangement consisting of quasi-2D CsPbCl perovskite and Yb layers. The successful preparation of layer arrangements resulted in the highly sensitized luminescence of Yb by CsPbCl with NIR PLQYs exceeding 130%, which is attributed to quantum cutting. In addition, Er luminescence at 1540 nm is acquired by the co-existence of Er with Yb in a layer, which is a result of the intralayer metal-to-metal energy transfer from Yb activated by CsPbCl via the interlayer quantum cutting process. The PLQY of Er luminescence reaches to 12.6%, which is the highest value ever observed for Er compounds, resulting from the efficient interlayer quantum cutting process over 100% and the following intralayer resonance metal to metal energy transfer with the efficiency over 80%.