Efficient and Bright Pure-Blue All-Inorganic Perovskite Light-Emitting Diodes from an Ecofriendly Alloy

Metal halide perovskite light-emitting diodes (PeLEDs) have been regarded as alternative candidates for full-color display applications with rapid progress to surge the external quantum efficiencies (EQEs) over 20%. However, in contrast to the high efficiencies of green, red, and near-infrared PeLEDs, the performance of their blue cousins is still lagging behind, especially the pure-blue one. Obtaining blue perovskite films with negligible nonradiative recombination loss and high stability is of great importance to realize efficient and spectrally stable blue PeLEDs. In this work, through partially replacing the toxic lead ions (Pb²⁺) with ecofriendly strontium ions (Sr²⁺) to tune the emission wavelength along with using passivation strategies, all-inorganic pure-blue perovskite films with a high photoluminescence quantum yield of 60.7% were achieved, which then delivered PeLEDs with a luminance of 510 cd m^-2 and an EQE of 1.43%. The device yields a record radiance among the most efficient PeLEDs at 467 nm. In addition, the resultant PeLEDs displayed exceptional spectral stability during the electrical bias operation. Our work provides a promising avenue to develop environmentally friendly perovskite materials for efficient and spectrally stable pure-blue PeLEDs and beyond.