Fluorene co-polymers with high efficiency deep-blue electroluminescence

Abstract

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High brightness deep blue/violet fluorescent polymer light-emitting diodes (PLEDs)

“…The polymers are deep blue / violet emitters (λ max PL in thin films: 421 and 401 nm, respectively). They exhibit very little solvatochromism, in agreement with previous work on fluorene co-polymers; 29,30,32 the small changes observed can be explained by the different refractive index of the solvents. From the photophysical data in Table 2 it can be observed that both CF1 and CF2 emissions peak at ca.…”

“…29,30,31 In an alternative approach, 9,9diphenylfluorene units serve to disrupt conjugation in the polymer backbone leading to PLEDs with EQE values of η ext, max 3.9%, L max of 274 cd m -2 with CIE xy coordinates (0.17, 0.07). 32 It is also established that meta-linked aromatic units in the backbone can blue shift emission by reducing the effective conjugation length. 33,34,35 Very preliminary electroluminescence data showed blue emission (EQE 1.32%; CIE xy 0.16; 0.11).…”

Small Donor–Acceptor Molecules Based on a Quinoline–Fluorene System with Promising Photovoltaic Properties

“…In compounds based on D–A systems, fluorenes and their derivatives are broadly used as electron donors, and quinolines,17 benzotriazoles,18,19 arylimides,20 and cyanoacetic acid21 functions are used as acceptor moieties. Fluorenes, polyfluorenes, and their derivatives show potential in optoelectronics and photonics as blue light emitters and are used widely in OLEDs,22 as hosts in green and sky blue phosphorescent OLEDs (PhOLEDs),23–26 in solar cells (SCs),27 and in FETs 28. However, fluorene derivatives exhibit lower power efficiencies or excited‐state lifetimes compared with those of polymeric green and red emitters, for instance; however, on the other hand, they possess excellent chemical and thermal stabilities, good solubilities, electron‐transport properties, and reasonably high fluorescence quantum yields 29,30.…”

Deep‐blue light‐emitting polyfluorenes containing spiro[fluorene‐9,9′‐thioxanthene‐S,S‐dioxide] isomers

“…Adopting weak conjugate structure in polymer backbone is also a good strategy to realize deep‐blue emission. The carbazole‐alt‐fluorene copolymers with CIE coordinates of (0.16, 0.08) and the poly(fluorenes‐co‐9,9‐diphenylfluorene)s with CIE coordinates of (0.16, 0.07) were prepared by meta‐linked carbazole unit in the backbone and by 9,9‐diphenylfluorene to disrupt backbone π‐conjugation, respectively …”