Large-Area Blade-Coated Deep-Blue Polymer Light-Emitting Diodes with a Narrowband and Uniform Emission

Large-area polymer light-emitting diodes (PLEDs) manufactured by printing are required for flat-panel lighting and displays. Nevertheless, it remains challenging to fabricate large-area and stable deep-blue PLEDs with narrowband emission due to the difficulties in precisely tuning film uniformity and obtaining single-exciton emission. Herein, efficient and stable large-area deep-blue PLEDs with narrowband emission are prepared from encapsulated polydiarylfluorene. Encapsulated polydiarylfluorenes presented an efficient and stable deep-blue emission (peak: 439 nm; full width at half maximum (FWHM): 39 nm) in the solid state due to their single-chain emission behavior without inter-backbone chain aggregation. Large-area uniform blade-coated films (16 cm(2)) are also fabricated with excellent smoothness and morphology. Benefitting from efficient emission and excellent printed capacity, the blade-coated PLEDs with a device area of 9 mm(2) realized uniform deep-blue emission (FWHM: 38 nm; CIE: 0.153, 0.067), with a corresponding maximum external quantum efficiency and the brightness comparable to those of devices based on spin-coated films. Finally, considering the essential role of deep-blue LEDs, a preliminary patterned PLED array with a pixel size of 800 x 1000 mu m(2) and a monochrome display is fabricated, highlighting potential full-color display applications.

Automated summary

Large-area polymer light-emitting diodes (PLEDs) with efficient and stable deep-blue emission are successfully fabricated through encapsulated polydiarylfluorene material. The blade-coated PLEDs exhibit excellent uniformity and morphology, achieving uniform deep-blue emission comparable to spin-coated films. Furthermore, a patterned PLED array with a monochrome display is demonstrated, showing the potential for full-color display applications.