Abstract
Obtaining efficient blue emission from CdSe nanoplatelets (NPLs) remains challenging due to charge trapping and sub-bandgap emission. Thanks to a design-of-experiments (DoE) approach, we significantly improved the NPL synthesis, obtaining precise control over the lateral aspect ratio (length/width). We raised the photoluminescence quantum efficiency up to 66% after growth of a CdS crown, with complete elimination of trap-state emission. Using these 3.5 monolayer, blue-emitting CdSe/CdS core/crown NPLs (λ = 460 nm), we fabricated light-emitting diodes (LEDs) with narrowband (16 nm) blue electroluminescence, an external quantum efficiency of 1.3% and low turn-on voltage of 2.9 V after DoE optimization. Our findings show that NPLs are a promising system to obtain LEDs that emit a saturated blue color.