Soochow University researchers have proposed the in situ treatment of Cl-rich benzene phosphorus oxydichloride (BPOD)as a way to achieve high-quality pure-blue perovskites, by simultaneously enlarging the perovskite bandgap, passivating the halide vacancy defects, and immobilizing the halide ions through the hydrolysis products of chloride ions and phenylphosphonic acid.
The background for this work is that despite the substantial progress in sky-blue (480−495 nm) perovskite light-emitting diodes (PeLEDs), pure-blue PeLEDs (<480 nm) merely show moderate performances. Bromide-chloride mixed perovskites may have potential to enable a straightforward and effective way to obtain pure-blue emission, but the tricky issue of halide migration in mixed halide perovskites makes it challenging to achieve efficient PeLEDs with stable electroluminescence (EL) spectra.
In their recent work, the team showed efficient pure-blue PeLEDs with a maximum external quantum efficiency (EQE) of 9.3% at 477 nm, an impressive lifetime of 34.7 min at 104 cd m−2, and very stable EL spectra, which are superior to the conventional mixed halide PeLEDs based on lead-chloride precursor, representing one of the best performances for mixed halide pure-blue PeLEDs.
Therefore, this work opens the door to a feasible and effective method for efficient and stable pure-blue PeLEDs.
