Fluorene derivatives for highly efficient non-doped single-layer blue organic light-emitting diodes

• New fluorene derivatives were synthesized for non-doped single-layer OLEDs.
• One of derivatives exhibits deep-blue emission in device.
• Derivative with thienyl unit shows best OLED device performance.
• Emission color is tunable by changing the conjugation core and/or length.

Diphenylamino- and triazole-endcapped fluorene derivatives which show a wide energy band gap, a high fluorescence quantum yield and high stability have been synthesized and characterized. Single-layer electroluminescent devices of these fluorene derivatives exhibited efficient deep blue to greenish blue emission at low driving voltage. The single-layer OLED of PhN-OF(1)-TAZ shows a maximum current efficiency of 1.54 cd/A at 20 mA cm−2 with external quantum efficiency (EQE) of 2.0% and CIE coordinates of (0.153, 0.088) in deep blue region, while the single-layer device of oligothienylfluorene PhN-OFOT-TAZ shows a maximum brightness of 7524 cd/m2 and a maximum current efficiency of 2.9 cd/A with CIE coordinates of (0.20, 0.40) in greenish blue.

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