Ultra broadband emission toward white LED based on dysprosium double perovskites CsxRb3-xDyCl6-xIx

Lead-free halide double perovskite (HDP) materials have become one of the hot spots due to their remarkable photoelectric properties, including broadband emission due to self-trapped excitons from soft lattice and strong exciton-phonon coupling. However, the optical and optoelectronic properties are hampered in the visible and infrared region, because of a wide or indirect band gap in metal HDPs. So far, doping lanthanide ions is an efficient method to modify the optical properties of HDP materials. Here, we have successfully synthesized dysprosium-based double perovskite (Cs x Rb 3-x DyCl 6-x I x ) crystals through a straightforward hydrothermal method. A very broad band emission covering almost the whole visible spectrum from 400 nm to 700 nm is fulfilled, resulting in a strong white light emission. Further, the hue of the white light can finely be adjusted, via tuning the excitation wavelength. High pressure-induced luminescence enhancement has also been demonstrated. Based on the Cs x Rb 3-x DyCl 6-x I x crystals, we have also fabricated a series of white light-emitting diodes, with the color coordinates of (0.33, 0.33), illustrating its great potential in the solid-state lighting applications. The dysprosium-based double perovskite studied in this work offers us a nice choice for designing HDP-based white light emitting devices.