428865-53-6Relevant academic research and scientific papers
Fluorescence quenching and enhancement of vitrifiable oligofluorenes end-capped with tetraphenylethene
Aldred, Matthew P.,Li, Chong,Zhang, Guo-Feng,Gong, Wen-Liang,Li, Alexander D. Q.,Dai, Yanfeng,Ma, Dongge,Zhu, Ming-Qiang
, p. 7515 - 7528 (2012/06/01)
We report the synthesis of novel amorphous fluorene-based fluorophores that have been end-capped with tetraphenylethene (TPE). Although in the solid state the fluorophores show bright cyan fluorescence with high (68%) photoluminescence quantum efficiency (PLQE), strong fluorescence quenching is observed in solution with low PLQE values ranging from 0.3% to 2.1%. When the fluorophores were added to a 90% water-THF solvent mixture nanoparticles were formed, which was confirmed by Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM). Subsequent fluorescence measurements reveal that all the fluorophores exhibit aggregation induced emission (AIE) with high PLQE (41%). We have carried out a comparative study of 5 fluorene-based TPE materials (F(1-5)TPE), in which the fluorene core is extended, and investigated their thermal, optical, electrochemical and electroluminescence properties. From fluorescence quantum yield data we have discovered that the AIE effect decreases as the fluorene core increases both in the nanoparticle and in the solid state. Thermal analysis reveals that all fluorophores are amorphous with high thermal stabilities. Potential application in solid state vapour sensing has been demonstrated using dichloromethane that shows "on" and "off" fluorescence behaviour. Finally, Organic Light Emitting Diodes (OLEDs) have been fabricated with device configuration ITO/PEDOT/F(1-5)TPE/TPBi/LiF/Al. The best OLED device that incorporates F1-TPE as the emitter exhibits a turn-on voltage of 5.8 V, Lmax = 1300 cd m-2, ηP,max = 1 lm W -1 and ηC,max = 2.6 cd A-1.
Synthesis, characterization, photo-induced alignment, and surface orientation of poly(9,9-dioctylfluorene-alt-azobenzene)s
Kinashi, Kenji,Kambe, Yuki,Misaki, Masahiro,Koshiba, Yasuko,Ishida, Kenji,Ueda, Yasukiyo
, p. 5107 - 5114 (2013/01/15)
Three types of bi-functionalized copolymers (P1FAz, P2FAz, and P3FAz) with different numbers of fluorene units and an azobenzene unit were synthesized and characterized using UV-vis and polarized absorption spectroanalysis. The trans-cis photoisomerization was conformed under 400 nm light irradiation for all copolymers in chloroform. However, in the film state, only the trans-cis photoisomerization occurred by mono-fluorene attached copolymer poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-4,4′-azobenzene)] (P1FAz). Photo-induced alignment was achieved using the P1FAz film after irradiation with linear polarized 400 nm light and subsequent annealing at 60 °C. Surface orientation of a spin-coating film of poly(9,9-didodecylfluorene) (F12) was achieved using the photo-induced alignment layer of the P1FAz film after annealing at 90°C. The photo-induced alignment layer of P1FAz has potential application to the surface orientation technique for appropriate polymers, which will be useful for the fabrication of optoelectronics devices.
Deep-blue and white organic light-emitting diodes based on novel fluorene-cored derivatives with naphthylanthracene endcaps
Zhang, Ting,Liu, Di,Wang, Qian,Wang, Renjie,Ren, Huicai,Li, Jiuyan
, p. 12969 - 12976 (2011/12/21)
Novel fluorene based deep-blue-emitting molecules with naphthylanthracene endcaps, namely 2,7-di(10-naphthylanthracene-9-yl)-9,9-dioctylfluorene (NAF1) and 7,7′-di(10-naphthylanthracene-9-yl)-9,9,9′,9′-tetraoctyl- 2,2′-bifluorene (NAF2), are synthesized by a Suzuki cross-coupling reaction. These materials exhibit excellent thermal and amorphous stabilities, and high fluorescence quantum yield of over 70%. Organic light-emitting devices (OLEDs) using NAF1 or NAF2 as non-doped emitter exhibit bright deep blue electroluminescence with CIE coordinates of (0.15, 0.13) for NAF1, (0.16, 0.13) for NAF2. A maximum power efficiency of 2.2 lm W-1 (4.04 cd A -1, 4.04%) is achieved for NAF1, which is among the highest values ever reported for deep-blue fluorescent OLEDs. A further improved coordinates of (0.15, 0.09) with efficiencies of 3.56 cd A-1 and 2.10 lm W -1 are achieved for NAF1 upon tuning device thickness, which are also among the best data for non-doped deep blue fluorescent OLEDs with a CIE coordinate of y -1 (7.66 cd A -1), a brightness of 12090 cd m-2, and a standard white light coordinates of (0.33, 0.33). This performance is among the best results ever reported for two-emitting-component white OLEDs based on fluorescent materials.
Synthesis and characterization of alternating copolymers of fluorene and oxadiazole
Ding, Jianfu,Day, Michael,Robertson, Gilles,Roovers, Jacques
, p. 3474 - 3483 (2007/10/03)
Alternating copolymers of 9,9-dioctylfluorene and oxadiazole have been prepared by the tetrazole route or the Suzuki coupling reaction. In the polymers the oxadiazole units were evenly dispersed in the main chain at every one, P(F1-alt-Ox), three, P(F3-alt-Ox), or four, P(F4-alt-Ox), fluorene units. Another copolymer with an asymmetric repeat unit structure, P(F3-Ox-F1-Ox) has also been prepared for comparison. In this study, the tetrazole route has been demonstrated to offer several advantages for preparing polyoxadiazole with well-defined structures compared to other oxadiazole ring formation reactions. These advantages include: clean and fast reactions, mild reaction conditions, high yields, and high molecular masses of product. The glass transition temperature of copolymers ranged from 98 to 150 °C, and the copolymers show high thermal stability with decomposition temperatures around 430 °C. The UV-vis absorption and photoluminescence properties of all the copolymers in solutions are similar to those of poly(9,9-dioctylfluorene). All copolymers fluoresce in the blue-light range with quantum yields of ～70% in CH2Cl2 solution.
