What question did this study set out to answer?

This research aims to explore how boron incorporation affects the optical properties of carbazolocarbazoles, particularly their afterglow and electroluminescence.

March 2, 2026Open Access

Boron Doping Modulates Carbazolocarbazoles with Color-Tunable Afterglow and Long-Lived Electroluminescence

Key Points

This research aims to explore how boron incorporation affects the optical properties of carbazolocarbazoles, particularly their afterglow and electroluminescence.
Systematic investigation of a series of carbazolocarbazole derivatives: tOCCz, tBOCCz, and tDBOCCz.
Assessment of afterglow properties under varying temperatures (300 K and 77 K).
Evaluation of electroluminescence characteristics in an organic light-emitting diode using tBOCCz.
Measurement of driving voltage, luminance, and external quantum efficiency.
Boron doping results in color-tunable afterglow, shifting from green-yellow at 300 K to orange-red at 77 K.
Afterglow OLED using tBOCCz achieves a low driving voltage of 2.8 V and a luminance of 22,021 cd m–2.
The device exhibits a high external quantum efficiency of 5.0% and a visible electroluminescence lasting approximately 2 seconds.

Abstract

Carbazolocarbazole (CCz) frameworks represent a promising class of afterglow-active emitters owing to their rigid helical π-systems. Here, we systematically investigate the effect of boron incorporation in a series of CCz derivatives (tOCCz, monoboron tBOCCz, and diboron tDBOCCz). Boron doping induces color-tunable hybrid afterglow combining thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), with lifetimes exceeding 0.2 s and thermochromic shifts from green-yellow (300 K) to orange-red (77 K). Remarkably, an afterglow organic light-emitting diode (OLED) using tBOCCz as a single dopant achieves a low driving voltage of 2.8 V, record-high luminance of 22,021 cd m–2, a high external quantum efficiency of 5.0%, and ultralong electroluminescence (EL) visible for ∼2 s (lifetime 263 ms). Achieving high efficiency, high brightness, and extended EL duration together marks a benchmark for afterglow OLEDs. Overall, boron doping provides a versatile molecular strategy to realize color-tunable afterglow and durable EL for future responsive optoelectronics.

Boron Doping Modulates Carbazolocarbazoles with Color-Tunable Afterglow and Long-Lived Electroluminescence

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Abstract

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