Improving optoelectronic properties of the 2,7‐polyfluorene derivatives with carbazole and oxadiazole pendants by incorporating the blue‐emitting iridium complex pendants in C‐9 position of fluorine unit

Abstract

To study the influence of a blue‐emitting iridium complex pendant on the optoelectronic properties of its 2,7‐polyfluorene (PF) derivatives with the carbazole and oxadiazole pendants, a class of 2,7‐PF derivatives containing carbazole, oxadiazole, and/without the cyclometalated iridium complex pendants in the C‐9 positions of fluorene unit were synthesized. Their thermal, photophysical, electrochemical, and electroluminescent (EL) properties were investigated. Among these 2,7‐PF derivatives (P1–P4), P2 and P3 exhibited higher photoluminescence efficiency in dichloromethane and better EL properties in the single‐emissive‐layer polymer light‐emitting devices. The highest brightness of 3888 cd/m2 and the maximum current efficiency of 2.9 cd/A were obtained in the P2‐ and P3‐based devices, respectively. The maximum brightness and efficiency levels were 1.7 and 2.1 times, respectively, higher than the corresponding levels from the parent 2,7‐PF derivative (P1)‐based devices. Our work indicated that EL properties of 2,7‐PF derivatives can be improved by introducing the blue‐emitting iridium complex into the alkyl side chain of fluorine unit as pendant. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Tunable Electrofluorochromic Device from Electrochemically Controlled Complementary Fluorescent Conjugated Polymer Films

“…To provide wider emission color range, higher on/off ratio, and faster switching performance, we adopt herein a greenish-yellow emitting P1 and a blue emitting P2 as our complementary partners for our multicolor EFCD (Scheme ). Fluorene-based conjugated polymers (PFs) are of great interest as light-emitting materials because of their high photoluminescence (PL) efficiency and excellent thermal stability in the solid state. − On the other hand, triarylamines (TAAs) are known to be oxidized easily to form stable radical cations, an effective quencher. − Incorporation of TAAs onto the fluorescent conjugated polymers as a switch becomes a useful idea for controlling EFCDs. Meanwhile, to benefit the ion transport during the electrochemical process and reduce the barrier of the triphenylamine radical cation formation, a dipolar cyclic urea moiety was also introduced into the polymer backbone .…”

White-light electrofluorescence switching from electrochemically convertible yellow and blue fluorescent conjugated polymers

“…Fluorene-based conjugated polymers (PFs) are of great interest as light-emitting materials due to their high photoluminescence (PL) efficiency and excellent thermal stability in the solid state. [25][26][27][28][29][30][31][32][33][34][35][36] Since we have successfully prepared the blue light emitting EF polymer P2 in the last study, we are interested in further developing a novel PF based polymer P1 that has the color tuned through incorporation of the electron-decient benzo [2,1,3]thiadiazole (BT) units [37][38][39][40][41] so that the emission could cover a wider range to the yellow color spectral region (Scheme 1). In addition, it would be an appropriate choice to adopt triarylamine as a switching unit to facilitate the uorescence on/off through a redox mechanism.…”

Electrochemical fluorescence switching properties of conjugated polymers composed of triphenylamine, fluorene, and cyclic urea moieties

“…However, it is difficult to maintain long‐term morphological stability of thin films due to crystallization or phase separation. Several methods have been used to overcome this drawback, such as introduction of bulky groups at the C‐9 position of the fluorene, copolymerization with other electroactive monomers, and optimization of EL device configurations 40–51. We expect that modification of the PFs by introduction of cyclic urea and propeller‐shaped triphenylamine units into the polymer backbone can increase morphological stability.…”