Near-infrared emission of CaAl6Ga6O19:Cr3+,Ln3+ (Ln = Yb, Nd, and Er) via energy transfer for c-Si solar cells

A series of CaAl6Ga6O19:Cr3+,Ln3+ (Ln = Yb, Nd, and Er) novel near-infrared (NIR) emitting phosphors were prepared via a high-temperature solid-state reaction. The luminescence spectra and decay lifetimes of these samples were measured to prove the energy transfer process from the Cr3+ to Ln3+ ions. The CaAl6Ga6O19:Cr3+,Ln3+ (Ln = Yb, Nd, and Er) phosphors can efficiently convert the short-wavelength sunlight in the near-ultraviolet and visible (UV-Vis) regions into near-infrared emission, which matches the higher sensitivity region of the c-Si solar cells. The maximal energy transfer efficiencies of CaAl6Ga6O19:Cr3+,Ln3+ (Ln = Yb, Nd, and Er) were 25.84%, 73.90%, and 29.46%, respectively. Our results show that the CaAl6Ga6O19:Cr3+,Ln3+ (Ln = Yb, Nd, and Er) phosphors have potential applications as luminescent downshifting convertors for enhancing the photoelectric conversion efficiency of the c-Si solar cells.