Blue perovskite light-emitting diodes based on RbX-doped polycrystalline CsPbBr3 perovskite films

Blue perovskite light-emitting diodes (PeLEDs) still exist some problems, such as low light-emitting efficiency, low brightness and color instability with regard to the counterparts of green and red PeLEDs. Chlorine-containing polycrystalline perovskites have been used to realize the blue electroluminescence (EL) with satisfied color purity. However, poor solubility of chlorine sources during the wet-process preparation of a polycrystalline perovskite film largely influences the film quality and the resultant EL behavior. Herein, a series of blue emissive polycrystalline perovskite films were prepared by employing RbX (X = Cl or Br) with a relatively good solubility as dopants in the CsPbBr3 perovskite film. The RbX-incorporated CsPbBr3 perovskite not only realizes blue emission, but also improves the film coverage from 80% to 99%. The corresponding RbBr- and RbCl-doped CsPbBr3 PeLEDs demonstrate bright blue emission with EL peaks located at 492 nm and 468 nm, respectively.