Full-spectrum driven UV–visible to NIR photon down-conversion phosphors toward crystalline silicon solar cell applications

In this work, a novel and efficient full-spectrum driven ultraviolet–visible to near-infrared photon down-conversion phosphor Ca 3 ScHfAlSi 2 O 12 : Eu 2+ , Nd 3+ was successfully designed and synthesized. The conversion layer fabricated with this phosphor significantly enhanced photon sensitivity and external quantum efficiency of crystalline silicon solar cells in 300–800 nm wavelength range. The power conversion efficiency (PCE) of the crystalline silicon (c-Si) solar cells reaches an efficiency bottleneck (∼30 %) because of the spectral mismatch between the solar spectrum and the spectral response of c-Si solar cells. Photon down-conversion technology is believed as an effective method to reduce the intrinsic energy loss and break such efficiency limit of c-Si solar cells. However, developing an efficient full-spectrum driven photon down-conversion material that can simultaneously convert ultra-broadband ultraviolet (UV) and visible light to near-infrared (NIR) light is still a great challenge. In this work, an efficient full-spectrum driven UV–visible to NIR photon down-conversion phosphor Ca 3 ScHfAlSi 2 O 12 : Eu 2+ , Nd 3+ is reported towards improving the PCE of c-Si solar cells. Both the diffuse reflectance and photoluminescence excitation spectra analysis demonstrate that Ca 3 ScHfAlSi 2 O 12 : Eu 2+ , Nd 3+ have ultra-broadband spectral absorption that simultaneously covers UV–visible light region from 250 to 750 nm, and can emits a broadband NIR emission centered at 780 nm (4f 6 5d → 4f 7 transitions of Eu 2+ ), and two narrow NIR emissions at 900 and 1064 nm ( 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 transitions of Nd 3+ ) under full-spectrum excitation. The efficient resonance energy transfer from Eu 2+ to Nd 3+ in Ca 3 ScHfAlSi 2 O 12 is demonstrated to account for the photon down-conversion process through spectroscopy and fluorescent decay curves analysis, with a high energy transfer efficiency of 56.62 %. Finally, both the photon sensitivity and the external quantum efficiency of c-Si solar cells has been increased within 300–800 nm based on the fabricated UV–visible to NIR photon conversion layer. The results not only provide an effective strategy to realize full-spectrum driven UV–visible to NIR photon down-conversion, but also can inspire more researchers to pay more attention to phosphors with ultra-broadband absorption characteristics and explore innovative applications in the field of photovoltaic energy conversion.