Sensitizing Full‐Spectrum Lanthanide Luminescence within a Semiconductor CaZnOS Host

A semiconductor CaZnOS host is utilized to sensitize luminescence through 4f–4f transitions of lanthanide dopant ions. Efficient energy transfer from the host to various lanthanide ions is achieved with the assistance of Cu⁺ or Mn²⁺ codopants. The host‐sensitized luminescent materials displaying full‐spectrum emission are used to construct near‐infrared light‐emitting devices.
Lanthanide ions are appealing for luminescence applications due to their sharp and tunable emission lines spanning the whole spectral range. However, the parity‐forbidden nature of the electronic transition in lanthanide ions typically results in ineffective excitation processes, which is a major obstacle to practical applications of lanthanide‐based luminescent materials. Herein, a general method to sensitize lanthanide luminescence within a semiconductor host of CaZnOS is developed. Efficient energy transfer from the host to a series of lanthanide ions with the assistance of Cu⁺ or Mn²⁺ codopants is demonstrated, which introduces intermediate energy states to mediate the energy transfer processes. Accordingly, a wide spectrum of emission is achieved by a single band excitation in the near‐ultraviolet region. Due to the efficient host sensitization, a phosphor‐converted light‐emitting diode (LED) is constructed by integrating the lanthanide‐doped CaZnOS with an ultraviolet LED chip, which is used for near‐infrared studies of biological tissues.