Blue light-emitting hyperbranched polymers using fluorene-co -dibenzothiophene-S,S -dioxide as branches

Synthesis and properties of hyperbranched polymers for polymer light emitting devices with sunlight-style white emission

A new series of hyperbranched polymers consisting of fluorene-alt-carbazole as the branches and the three-dimensional-structured spiro[3.3]heptane-2,6-dispirofluorene (SDF) as the core were designed and synthesized by one-pot Suzuki coupling polycondensation. A phosphor group with broad full width at half maximum (FWHM) bis(1-phenyl-isoquinoline)(acetylacetonato)iridium(iii) (Ir(Brpiq)2acac, 0.08 mol%) as the red-light emitting unit and bis(2-(4-bromophenyl)-1-[6-(9-carbazolyl)hexyl]-imidazole)(2-(5-(4-fluorinated phenyl)-1,3,4-triazole)pyridine)iridium(iii) ((CzhBrPI)2Ir(fpptz)) as the green-light emitting unit were introduced into the backbones to obtain sunlight-style white-light emission by adjusting the feeding ratios of (CzhBrPI)2Ir(fpptz) (0.08 to 0.32 mol%). The results indicate the synthesized polymers show high thermal stabilities and good amorphous film morphology because of the hyperbranched structures. Besides, the lowest unoccupied molecular orbital (LUMO) levels of polymers were reduced and the electron injection was improved because of excellent electron-transporting ability of the triazole unit in the green group. The hyperbranched structures can effectively suppress the polymers' chain distortion and aggregation, and promote the incomplete Förster resonance energy transfer (FRET) efficiency from fluorene-alt-carbazole segments to Ir complex units. As a result, the devices with hyperbranched polymer light-emitting layers realize white light emission, and the optimized device also exhibits good electroluminescent (EL) performance with Commission Internationale de l'Eclairage (CIE) coordinates at (0.32, 0.31), a maximum luminance of 9054 cd m-2, a maximum current efficiency of 3.59 cd A-1 and a maximum Color Rendering Index (CRI) of 91. The hyperbranched polymers based on fluorene-alt-carbazole branches and a SDF core and high-efficiency phosphor groups with broad full width at half maximum are attractive candidates for sunlight-style white polymer light-emitting device.

Multiple Stimuli-Responsive Fluorescence Behavior of Novel Polyamic Acid Bearing Oligoaniline, Triphenylamine, and Fluorene Groups

Multiple stimuli-responsive fluorescent materials have gained increasing attention for their fundamental investigation and intelligent applications. In this work, we report design and synthesis of a novel polyamic acid bearing oligoaniline, triphenylamine, and fluorene groups, which served as sensitive units and fluorescence emission unit, respectively. The resulting polymer exhibits multiple stimuli-responsive fluorescence switching behavior triggered by redox species, pH, electrochemical, and pressure stimuli. Every fluorescence switching mechanism upon each stimulus was studied in detail. The interactions and energy transfer between sensitive units and emission unit are largely responsible for this fascinating fluorescent switching behavior. This work provides a deep understanding of the optical switching essence upon these stimuli, opening the way for the development of new fluorescent sensing applications.

All-solution-processed fluorene/dibenzothiophene-S,S-dioxide blue co-oligomer light-emitting diodes with an electron transporting PEI/ultrafine-ZnO-nanoparticle bilayer

An all solution-processed blue organic light-emitting diode comprising the emissive fluorene/dibenzothiophene-S,S-dioxide co-oligomer and a poly-ethyleneimine/ultrafine-ZnO-nanoparticle bilayer is proposed for the first time.

Dual-core star-shaped single white polymers: the effect of host structure on luminescence properties

A new strategy for pure star-like polymers with white emission is presented to design dual-core polymers (DC-PFMs) which exhibit a higher quantum yield and a more efficient energy transfer from the host to the guest than traditional single-core polymers (SC-PFMs).

Solution-processable bipolar S,S-dioxide-dibenzothiophene chromophores for single-layer organic light-emitting diodes

Four novel solution processable small molecular chromophores that consist of regioisomeric S,S-dioxide-dibenzothiophene units are designed and synthesized.

Efficient saturated red light-emitting polyfluorenes containing iridium complexes in side chains

A maximum EQE of 7.8% with slow efficiency roll-off was attained based on a red light-emitting phosphorescent polymer PF-IrNiq1.

Feasible energy level tuning in polymer solar cells based on broad band-gap polytriphenylamine derivatives

Four triphenylamine based broad band-gap polymers with different substituted groups [–OC₈H₁₇, –C₈H₁₇, –CF₃, –(CF₃)₂] were designed and synthesized, and the HOMO energy levels and V_ocs of these polymer based PSCs could be tuned feasibly.

Efficient binary white light-emitting polymers grafted with iridium complexes as side groups

Efficient binary white-light-emitting electrophosphorescent copolymers were designed and synthesized via Suzuki polymerization.