This study introduces a novel molecular design to suppress Dexter transfer in hyperfluorescent OLEDs, which are promising for next-generation blue organic light-emitting diodes (OLEDs). Current hyperfluorescent OLEDs rely on high-gap matrices to prevent Dexter transfer, but this approach complicates device fabrication. The authors encapsulate ultranarrowband blue emitters with insulating alkylene straps, which significantly reduce Dexter transfer without the need for high-gap matrices. This design enables simple, efficient matrix-free hyperfluorescent OLEDs with a maximum external quantum efficiency (EQE) of 21.5% and narrow true-blue electroluminescence (EL) with a full-width at half-maximum (FWHM) of 14–15 nm. Transient absorption spectroscopy confirms that encapsulation effectively suppresses Dexter transfer, leading to negligible efficiency loss compared to non-doped devices. This work paves the way for highly efficient and stable blue OLEDs without the complexity of high-gap matrices.This study introduces a novel molecular design to suppress Dexter transfer in hyperfluorescent OLEDs, which are promising for next-generation blue organic light-emitting diodes (OLEDs). Current hyperfluorescent OLEDs rely on high-gap matrices to prevent Dexter transfer, but this approach complicates device fabrication. The authors encapsulate ultranarrowband blue emitters with insulating alkylene straps, which significantly reduce Dexter transfer without the need for high-gap matrices. This design enables simple, efficient matrix-free hyperfluorescent OLEDs with a maximum external quantum efficiency (EQE) of 21.5% and narrow true-blue electroluminescence (EL) with a full-width at half-maximum (FWHM) of 14–15 nm. Transient absorption spectroscopy confirms that encapsulation effectively suppresses Dexter transfer, leading to negligible efficiency loss compared to non-doped devices. This work paves the way for highly efficient and stable blue OLEDs without the complexity of high-gap matrices.