Fluorene‐based single‐chain copolymers with a white light emitter consisting of a blue and an orange chromophore have been synthesized and their photophysical and electroluminescent properties are investigated. The experimental results suggest that only a relatively small fraction of the orange‐emitting units incorporated into the fluorene is needed to achieve efficient white light emission by controlled incomplete energy transfer. A device from a copolymer with 0.02% DDQ content showed the highest external quantum efficiency of 2.64% with a luminance efficiency of 4.06 cd · A?1 with CIE coordinates (0.28, 0.24). The EL emissions are extremely stable over a wide range of current densities.
A new series of two poly(carbazole)‐based copolymers (poly(9‐hexyl‐carbazole‐co‐9‐(6‐(3‐(4‐phenylquinolin‐2‐yl)carbazol‐9‐yl)hexyl)carbazole) (PCVz) and poly(9,9‐dioctylfluorene‐co‐9‐(6‐(3‐(4‐phenylquinolin‐2‐yl)carbazol‐9‐yl)hexyl)carbazole) (PFCVz)) containing carbazoylphenylquinoline pendant groups were synthesized via the Suzuki coupling reaction for polymer light‐emitting diode applications. The electro‐optical properties of ITO/PEDOT/Polymer/PBD/LiF/Al devices based on these copolymers were investigated using UV‐visible, photoluminescence, and electroluminescence spectroscopy. The turn‐on voltages of the copolymer devices were found to be 6.0–8.0 V. The maximum brightness and luminescence efficiency of the copolymers device were found to be 230 cd · m?2 and 0.28 cd · A?1 at 11 V, respectively.
A copper‐catalyzed Ullmann C–N coupling reaction was used for the preparation of a new carbazole‐based HPU in good yield with a high molecular weight through a facile “AB2 + A2 + B2”‐type approach. The HPU exhibited good solubility, high thermal stability with a Tg of 196 °C, as well as a suitable HOMO level for good hole injection and transporting properties. A two‐layer OLED device, using HPU as hole‐transporting layer (HTL) and Alq3 as the light‐emitting layer, was fabricated to investigate the hole‐transporting properties of HPU. The luminance efficiency reached 1.14 cd · A?1 at the maximum current density of 1 240 mA · cm?2, while the maximum luminance efficiency was 1.65 cd · A?1, indicating the high morphological and thermal stability of HPU.
A new series of disubstituted polyacetylene derivatives that contain multi‐fluorine atoms on the pendent phenyl ring have been synthesized and characterized. The results reveal a greater red‐shift in UV‐vis absorption and PL emission upon incorporating more fluorine atoms on the pendent phenyl ring. Among them, disubstituted polyacetylene with a difluorophenyl group ( PDPA‐2F ) showed the highest luminescent efficiency. The device performance can be promoted by blending a hole‐transporting material TM‐TPD into PDPA‐2F as the active layer or by using a light‐emitting copolymer in which PDPA‐2F was copolymerized with a carbazole group ( PDPA‐2Fcab ). A light‐emitting diode of ITO/PEDOT/ PDPA‐2Fcab /Ca/Al revealed a maximum luminescence of 4230 cd · m?2 at 14 V and a maximum current efficiency of 3.37 cd · A?1 at 7 V.
The synthesis, thermal and emission properties of an electrophosphorescent platinum(II) metallopolyyne polymer consisting of 9‐butylcarbazole‐2,7‐diyl spacer P1 are described. The optical and electronic properties of P1 are compared to their molecular diplatinum(II) and digold(I) model complexes. The photophysical properties of P1 are somehow analogous to its 2,7‐fluorene‐linked congener but differs significantly from that for the 3,6‐carbazole derivative. Its optical band gap is notably reduced as compared to that for the 3,6‐carbazole analog. Multi‐layer polymer light‐emitting diodes (PLEDs) were fabricated with P1 as the emitting layer which gave a strong green‐yellow electrophosphorescence. The best PLED can reach the maximum current efficiency of 4.7 cd · A−1 at 5 wt.‐% doping level, corresponding to an external quantum efficiency of 1.5%. This represents the first literature example of efficient PLEDs exhibiting pure triplet emission under electrical excitation for metallopolyynes without the concomitant singlet emission. For safety concern, this metallopolymer was also tested for possible cytotoxicity and it does not show significant cytotoxic activity on liver and breast derived human cells at reasonable doses, rendering this functional material safe to use in practical devices.
Several poly(N‐phenyl‐2,7‐carbazole)s that have dialkoxy groups at the m‐ and p‐positions (PmpCzDC, PmpPhDC, PmpCBiDC, PmpEHC), a silyl group at the p‐position (PpPhDSiC), and a diphenylamino group (PmPhDAC, PmEHAC) at the m‐position of the N‐phenyl portion are synthesized, and their optical properties are characterized. These polymers have been used as emitting layer materials of organic light‐emitting diode (OLED) devices that have a configuration of ITO/PEDOT(PSS)/polymer/CsF/Al. The OLED devices embedded with PmpCzDC, PmpPhDC, and PmpEHC show intense luminance of about 15 000 cd · m?2 with efficiencies of about 1 cd · A?1, while the devices embedded with PpPhDSiC, PmPhDAC, and PmEHAC show less luminance but retain the color purity of blue emission under a wide range of applied voltages.
CROP has been used to synthesize well‐defined POXZ with a monofunctional (iodomethane) or a bifunctional (1,3‐diiodopropane) initiator. POXZ has been functionalized with an azido group at one (α‐azido‐POXZ, = 3.58 × 103 g · mol?1) or both ends (α,ω‐azido‐POXZ, = 6.21 × 103 g · mol?1) of the macromolecular chain. The Huisgen 1,3‐dipolar cycloaddition has been investigated between azido‐POXZ and a terminal alkyne on a small or larger molecule (PEG). In each case, the click reaction has been successful and quantitative. In this way, different telechelic polymers (polymers bearing different functions such as acrylate, epoxide, or carboxylic acid) and block copolymers of POXZ and PEG have been prepared. The polymers have been characterized by means of FTIR, 1H NMR, and SEC.
Conjugated polyelectrolytes and their neutral precursors: aminoalkyl‐substituted polyfluorenes (PFNs) with different 4,7‐bis(N‐methylpyrrol‐2‐yl)‐2,1,3‐benzothiadiazole (PBT) contents were synthesized by Suzuki coupling reaction. Their quaternized ammonium polyelectrolyte derivatives were obtained through a post‐polycondensation treatment on the terminal amino groups. The resulting copolymers PFNBr–PBT are soluble in polar solvents such as methanol, DMF, and DMSO. Using the conjugated polyelectrolytes PFNBr–PBT5 as gate dielectric material, poly(3‐hexylthiophene) (P3HT) ‐based field‐effect transistors (FETs) show a high drain current of almost 4.5 mA within a gate voltage of only ?3 V. The calculated hole mobility of P3HT is about 0.58 cm2 · V?1 · s?1.
Three phosphorescent dendrimers ( IrC1 , IrC3 , and IrF2 ) with an iridium complex core and oligocarbazole or oligofluorene substituted ligands were synthesized and characterized. The structures of the oligocarbazole were designed to maintain high triplet energy of the ligands so that phosphorescence quenching in the resulting dendrimers can be prevented, while the oligofluorene in IrF2 resulted in undesired phosphorescence quenching. Best performance was obtained from an IrC3 based electrophosphorescent light‐emitting device with a maximum luminance of 13 060 cd · m?2 at a driving voltage of 11.5 V and a peak current‐efficiency of 4.3 cd · A?1 at a luminance of 3 400 cd · m?2, owing to its high PL efficiency, and efficient energy transfer between the iridium complex core and the ligands.
Synthesis and characterization of a series of PAEs containing DPP units in the main chain are described. of the polymers was in the range 10 800–111 900. The polymers formed a deep blue solution in chloroform with absorption maxima between 589 and 645 nm and optical band gaps ranging from 1.61 to 1.74 eV. When excited at the absorption maxima, the polymer solutions showed red fluorescence with emission maxima between 656 and 676 nm. The polymers exhibited quasi‐reversible oxidation process with HOMO energy levels between ?5.60 and ?6.17 eV. EL properties of three polymers were investigated with device configuration ITO/PEDOT:PSS/Polymer/LiF/Al. When appropriate bias voltage was applied, a red EL with a maximum brightness of 17.5–24 cd · m?2 could observe from the devices.
New carbazole‐based copolymers, which contain various concentrations of 9‐alkyl‐3,6‐carbazole fragments in the main chain connected via alkylene spacers, have been synthesized by Ni(0)‐catalyzed Yamamoto‐type aryl‐aryl coupling reactions. Full characterization of the copolymer structure by NMR spectroscopy and elemental analysis is presented. These compounds represent amorphous materials of high thermal stability with glass transition temperatures of 151–162 °C and thermal decomposition starting at temperatures >390 °C. UV‐Vis absorption and photoluminescence emission of the copolymers confirmed that the effectively conjugated segment in the 3,6‐linked carbazole‐type copolymers is limited to dyads (dimeric units). However, copolymers with varying concentrations of the oligocarbazole chromophores demonstrate different charge injection and transport properties in multilayer light‐emitting diodes with the copolymers as the hole transport and Alq3 as the electroluminescent/electron transport layer. The device based on a copolymer composed of oligocarbazole blocks with an average length of around four carbazoles exhibited the best overall performance with a turn‐on voltage of 3.5 V, a maximal photometric efficiency of 4.1 cd · A?1 and maximum brightness of about 4 200 cd · m?2.
The polycondensation of trialkoxysilanes to PSSQs in a microreactor setup is demonstrated. While continuous‐flow processes involving microreactors found various applications in chain growth polymerization, their influence on step‐growth polymerization is less explored, and the polycondensation of multifunctional monomers has not been studied in detail. We found significantly increased yields and a decreased polydispersity of the obtained polymers in comparison to the batch process. By variation of the residence time molecular weights could be adjusted reproducibly ranging from = 1 900 to 11 000 g · mol?1. Thus, the microreactor setup offers for the first time the possibility to synthesize PSSQ with adjustable properties.
Summary: N‐Hexyl‐cyclopenta[c]pyrrole was synthesized and electrochemically and chemically polymerized to a novel 1,3,4‐alkyl‐substituted polypyrrole. The polymer was characterized in solution and as thin solid film by cyclic voltammetry, UV‐vis, FTIR and NMR spectroscopy, MALDI mass spectroscopy, GPC analysis, electrochemical quartz crystal microbalance, ESR spectroscopy and in situ conductivity. The polymer, with a defect‐free structure and an average degree of polymerization of 13 (electrochemically prepared) and 24 (chemically prepared), is soluble (>1%) in acetone, acetonitrile and chlorinated solvents. Its in situ conductivity as a function of potential and doping charge has the typical features of redox conductivity with a maximum value of ca 1 × 10?3 S · cm?1.
Structure of poly(N‐hexyl‐cyclopenta[c]pyrrole). 相似文献
The bromine chain‐end functionality of polystyrene (PSt) prepared by activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) was analyzed using 500 MHz 1H nuclear magnetic resonance (NMR). Bulk polymerization of styrene (St) was carried out with 50 ppm of copper in the presence of tris[2‐(dimethylamino)ethyl]amine (Me6TREN) ligand and tin(II) 2‐ethylhexanoate [Sn(EH)2] reducing agent at 90 °C. Due to the use of a low concentration of an active Cu/ligand catalyst complex, it was possible to significantly decrease the occurrence of catalyst‐based side reactions (β‐H elimination). As a result, compared to PSt prepared via normal ATRP, PSt with improved chain‐end functionality was obtained. For example, at 92% monomer conversion in normal ATRP only 48% of chains retained chain‐end functionality, whereas 87% of the chains in an ARGET ATRP still contained halogen functionality. PSt with controlled molecular weight ( = 11 600 g · mol?1, = 9 600 g · mol?1) and narrow molecular weight distribution ( = 1.14) was prepared under these conditions. In addition, as a result of decreased frequency of side reactions in ARGET ATRP, PSt with relatively high molecular weight was successfully prepared ( = 185 000 g · mol?1, = 1.35).
PANGMA nanofibers and nanomats with fiber diameters of 200–300 nanometers were fabricated by electrospinning. Cal‐B was covalently immobilized onto the PANGMA nanomats via three different immobilization routes. The properties of the Cal‐B‐immobilized PANGMA nanomats were assayed and compared with the free Cal‐B. The observed Cal‐B loading on these nanomats is up to ≈50 mg · g?1, and their hydrolytic activity is up to ≈2 500 nmol · min?1 · mg?1, much higher than free enzyme powder and also slightly higher than Novozyme 435. Cal‐B immobilized PANGMA nanomats have better reusability, thermal stability, and storage ability than free Cal‐B. They retain over 50% of their initial activity after 15 cycles, over 65% after 10 h heat incubation, and over 75% after 30 d storage.
A novel acrylamide/maleic acid copolymer [P(AM‐MA)] hydrogel nanofibrous membrane with a fiber diameter of ca. 120 nm is prepared by electrospinning an aqueous P(AM‐MA) solution with diethylene glycol as crosslinker, followed by a heat‐induced esterification crosslinking reaction at 145 °C. This hydrogel nanofiber can maintain a fiber form, but becomes distorted and merges to form many physical crosslinking points after immersion in water. The P(AM‐MA) hydrogel nanofibers are sensitive to external stimuli ionic strength and pH. Their water‐swelling ratio decreases with increasing solution ionic strength, and it shows a characteristic two‐step increase at pH = 2.5 and 8.5 in response to the increase of solution pH. The maximum water‐swelling ratios of the P(AM‐MA) hydrogel nanofibers are 18.1 and 22.5 g · g?1 in a solution of 0.05 mol · dm?3 ionic strength and in an aqueous solution of pH 11, respectively.
Benzo[1,2‐b:4,5‐b′]diselenophene (BDS) has been incorporated for the first time in a polymer. bis(Stannyl)‐functionalized BDS was copolymerized with 3,3′‐bis(alkyl)‐5,5′‐bithiophenes (dodecyl and tetradecyl side chains) through Stille copolymerization, to yield p‐type polymer semiconductors for organic field‐effect transistor application. The electronic and structural effect of the selenium atoms, compared to sulphur atoms in analogous copolymers, is described. The molecular weight has a decisive influence on the photophysical properties and supramolecular ordering, expressed in field‐effect transistor measurements. Saturation mobilities around 10?2 cm2 · V?1s?1 are obtained on standard silicon substrates.
A new high‐mobility low‐bandgap polymer, PBDT‐DODTBT, based on benzodithiophene and 5,6‐bis(octyloxy)‐4,7‐di(thiophen‐2‐yl)benzothiadiazole has been synthesized through a standard Stille coupling reaction. The polymer is soluble in common organic solvents, such as chloroform, tetrahydrofuran, and chlorobenzene and has excellent film forming properties. Preliminary studies of the copolymer showed the charge mobility as high as 7.15 × 10?3 cm2 · V?1 · s?1 from SCLC measurement. Initial photovoltaic cells based on the composite structure of ITO/PEDOT:PSS/PBDT‐DODTBT: α PC71BM (1:2)/Ca/Al showed an open‐circuit voltage of 0.76 V, a power conversion efficiency of 4.02%, and a short‐circuit current of 8.96 mA · cm?2.
1,2,4‐triazole‐functional PGMA polymers have been synthesized and their anhydrous proton‐conducting properties were investigated after doping with phosphoric acid and triflic acid. PGMA was prepared by solution polymerization and then modified with 1H‐1,2,4‐triazole (Tri) and 3‐amino‐1,2,4‐triazole (ATri). FT‐IR, 13C NMR and elemental analysis verify the high immobilization of the triazoles in the polymer chain. Phosphoric‐acid‐doped polymers showed lower Tg and higher proton conductivities. PGMA‐Tri 4 H3PO4 showed a maximum water‐free proton conductivity of approximately 10?2 S · cm?1 while that of PGMA‐ATri 2 H3PO4 was 10?3 S · cm?1. The structure and dynamics of the polymers were explored by 1H MAS and 13C CP‐MAS solid‐state NMR.
Two terthiophenes bearing core fluorinated thienyl units have been synthesised as potential semiconductor materials for organic field‐effect transistors. Polymerisation of these compounds has been achieved using conventional iron(III) chloride oxidative coupling methods and by electrochemical oxidation. Characterisation of the fluorinated materials has been achieved by absorption spectroscopy and cyclic voltammetry. A soluble hexyl‐functionalised polymer (poly 8b ) was used in an OFET device; hole mobilities were measured up to 3 × 10?3 cm2 · V?1 · s?1, and the device had an on/off ratio of 105 and a turn‐on voltage of +4 V.
