Isomeric engineering of dithieno[3,2-b:2′,3′-d]thiophene derivatives for efficient deep-blue OLEDs

Abstract

Simultaneously achieving deep-blue luminescence and high device performance remains a significant challenge for blue fluorescent emitters. In this study, a series of blue fluorescent isomers based on a dithieno[3,2-b:2′,3′-d]thiophene (DTT) core are rationally designed and synthesized. When incorporated into undoped OLEDs, all emitters exhibit stable blue emission with excellent color stability (ΔCIE < 0.01), achieving a maximum external quantum efficiency (EQE) of 3.94% and CIE coordinates of (0.14, 0.09). In doped configurations, these materials demonstrate efficient deep-blue emission with a maximum EQE of 3.97% and CIE coordinates of (0.15, 0.08), closely matching the NTSC standard for deep-blue emission (CIEy ≤ 0.08). This work establishes isomer-engineered DTT derivatives as promising candidates for high-performance deep-blue OLEDs, highlighting their potential for display and lighting applications.