Engineering linkers to regulate solid-state emission of spirodifluorene-based conjugated porous polymers for white light-emitting devices

Abstract

Conjugated porous polymers (CPPs) are preferred new luminescent materials in the field of photoelectronics. The unique porous and conjugated structures can successfully restrict the torsion of aromatic units, attenuate intermolecular π–π stacking, promote exciton mobility, and thus, enhance the fluorescence activity. Herein, spiro [3,3] heptane-2,6-bis(2′,2′′,7′,7′′-tetrabromo)spirofluorene (TBrSDF)-based conjugated porous polymers, CPP-1 and CPP-2, with different conjugation lengths were developed by condensation with 9,9-dioctylfluorene-2,7-diboronic acid (M₁) and 2,7-diethynyl-9,9-dioctylfluorene (M₂), respectively. A series of luminescent films for solid-state lighting were prepared by dispersing the two CPPs with different ratios in polymethyl methacrylate (PMMA) matrixes, and warm white light according to the commission internationale de l'eclairage (CIE) coordinates of (0.33, 0.44) was obtained with a ratio of 1 : 4. In addition, the two CPPs were used as light-converting materials coated directly onto the surface of ultraviolet light-emitting diodes (UV LEDs), and the CPP-2-coated LEDs emitted warm white light with CIE coordinates of (0.33, 0.37).