Researchers from Samsung Display, Korea Advanced Institute of Science and Technology (KAIST) and Dankook University recently reported an in-situ passivation strategy for pure-blue perovskite light-emitting diodes (PeLEDs), promising for next-generation displays, fabricated by vacuum thermal evaporation.
Image credit: Industrial Chemistry & Materials
The approach relies on a newly introduced phenanthroline-based compound, BUPH1, which is co-evaporated alongside the perovskite precursors. As the film forms, BUPH1 coordinates with under-coordinated Pb(II) ions, effectively passivating halide vacancies and suppressing ion migration in situ, which in turn enhances film morphology, raises photoluminescence efficiency, and stabilizes the emission spectrum without requiring additional fabrication steps.
This strategy is particularly significant because perovskite emitters, unlike many solution-processed materials, can be vacuum-thermally evaporated using the same tools already employed for OLED production. That compatibility means precise thickness control, fine patterning, and uniform dry processing can be directly translated into industrial manufacturing workflows.
Within this landscape, achieving a stable, high-purity blue emission is especially important for color-rich, high-resolution displays. The team’s optimized device emits at 472 nanometers with a narrow linewidth of 19 nanometers, aligning with the Rec.2020 standard for pure blue, and reaches an external quantum efficiency of 3.1% - said to be the highest reported so far for thermally evaporated pure-blue PeLEDs. Equally critical, the emission remains spectrally stable under electrical bias, showing no significant peak shifts or chromaticity changes across different operating conditions.
As Professor Byungha Shin of KAIST explains, passivating under-coordinated lead ions during growth opens a practical path toward overcoming the low efficiencies that have held back vacuum-processed perovskites. The demonstration of color-stable, high-purity blue emission through an industrially compatible process marks a promising step toward future high-performance displays.
Building on this foundation, the researchers now aim to extend device lifetime and increase luminance, advancing toward fully thermally evaporated perovskite stacks ready for widescale manufacturing.
