Molecular Design Opening Multiple Charge Transfer Pathways in Oxygen‐Bridged Boron Emitters for High‐Efficiency Pure Violet Organic Light‐Emitting Diodes

Why It Matters

Achieving high‑efficiency, high‑purity violet OLEDs unlocks advanced display, AR/VR, and secure communication applications, demonstrating a viable pathway for next‑generation MR‑TADF technologies.

Key Takeaways

• Oxygen‑bridged boron core enables dual short/long-range charge transfer
• Indole and benzofuran donors boost MR‑TADF performance
• Bulky tetraphenylsilane reduces aggregation, raising quantum yield
• BOID‑Cz‑Si achieves 22.7% EQE, record violet efficiency
• 420 nm peak, 25 nm FWHM gives high color purity

Pulse Analysis

Violet organic light‑emitting diodes have long lagged behind red and green counterparts due to intrinsic material challenges, including broad emission spectra and low external quantum efficiencies. Conventional emitters often suffer from strong intermolecular interactions that quench excited states, limiting both color purity and device performance. Recent advances in multiple‑resonance (MR) thermally activated delayed fluorescence (TADF) have offered a promising route, as MR‑TADF can produce narrowband emission while harvesting triplet excitons efficiently. However, extending these benefits into the deep‑violet region requires precise control over charge‑transfer pathways and molecular rigidity.

The breakthrough reported by the research team centers on an oxygen‑bridged boron scaffold functionalized with indole and benzofuran donor groups. This architecture creates parallel short‑range and long‑range charge‑transfer channels within a polycyclic aromatic framework, enhancing MR‑TADF characteristics. A bulky tetraphenylsilane moiety and an auxiliary carbazole unit further suppress aggregation, preserving high photoluminescence quantum yields (up to 95%). The resulting emitters, BOID‑Cz‑Si and BOBF‑Cz‑Si, exhibit pure violet peaks around 400 nm with a remarkably tight 25 nm bandwidth, meeting stringent color‑purity standards for display technologies.

Device integration demonstrates the practical impact: the BOID‑Cz‑Si OLED delivers a 420 nm emission peak and a 22.7% external quantum efficiency, positioning it among the most efficient violet emitters to date. Such performance not only advances high‑definition display panels and head‑mounted AR/VR systems but also opens avenues for secure optical communication that relies on short‑wavelength light. The study validates a modular molecular‑design strategy that can be adapted to other color regimes, suggesting a scalable path toward next‑generation, high‑efficiency MR‑TADF OLEDs across the visible spectrum.