Toward high-performance and stable blue perovskite light-emitting diodes via optimized fluorinated polymer blend hole transport layers.

Perovskite light-emitting diodes (PeLEDs) are promising low-cost, solution-processable, and color-pure optoelectronic devices for display and lighting applications. However, blue PeLEDs continue to lag their green and red counterparts in terms of luminance and operational lifetime, limiting their practical implementation. The performance disparity primarily arises from charge injection imbalance, which accelerates degradation at the perovskite/hole transport layer (HTL) interface under electrical bias. Here, we design a polymer blend HTL comprising poly(N-vinyl-2,7-difluoro-carbazole) (PVK-F) and poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA), in which strengthened van der Waals interactions promote denser molecular packing. This optimized microstructure simultaneously enhances hole mobility and wettability, enabling high-quality perovskite film formation. Consequently, PeLEDs emitting at 485 nanometers achieve an external quantum efficiency of 24.1% and luminance exceeding 26,000 candela per square meter. Moreover, the improved hole injection mitigates interfacial degradation, yielding an operational half-lifetime exceeding 700 minutes at an initial luminance of 100 candela per square meter. This work establishes polymer blending as an effective strategy for advancing the performance and stability of blue PeLEDs.