Synthesis and characterization of fluorene-carbazole and fluorene-phenothiazine copolymers with carbazole and oxadiazole pendants for organic light emitting diodes

We report the synthesis and characterization of new series of the fluorene based polymers with carbazole and oxadiazole pendants for the generation of the white emission out of the EL device. In the fluorene backbone, hole transporting units such as carbazole or phenothiazine were incorporated to improve the EL brightness and efficiency. The PFCzOxd-co-PCzs and PFCzOxd-co-PPTZs in EL spectra showed maximum peaks at around 430 nm and additional large peaks at around 530 and 500 nm, respectively. In case of PFCzOxd-alt-PCz and PFCzCzPCz-co-PFOxdOxdPCz, the EL spectra of the polymers showed two distinct peaks comprising the maximum at 427 nm, which corresponds to the EL spectra of the conjugated backbone, and additional broad peaks at around 540 and 530 nm, respectively. The CIE coordinates of the devices from PFCzOxd-alt-PCz and PFCzCzPCz-co-PFOxdOxdPCz were (0.28, 0.33) and (0.25, 0.32), respectively, approaching the value of the standard white of National Television System Committee (NTSC) (0.33, 0.33).     

Enhancing the electroluminescence properties of novel blue light emitting polymer and MEH‐PPV based white light emitting polymer devices by processing condition optimization

A series of triarylaminooxadiazole‐containing tetraphenylsilane light emitting polymer (PTOA) and poly(2‐methoxy, 5‐(2′‐ethyl‐hexyloxy)‐p‐phenylene‐vinylene) (MEH‐PPV) based white light emitting polymer devices (PLEDs) were fabricated to study blue and orange–red emitter composition and light emitting layer processing effects on white emission electroluminescence properties. Color purity, current turn‐on voltage, brightness, and current efficiency were strongly determined by MEH‐PPV content and the thin film processing condition. The intensity of PTOA blue emission was equal to that of MEH‐PPV orange–red emission when the device was fabricated by a polymer composite film containing 10 wt % of MEH‐PPV. Color purity [Commission Internationale de L'Eclairage (CIE_x,y) coordinates (0.26,0.33)] was nearly white emission under applied 8 V. The brightness and current efficiency of PTOA‐MEH‐PPV composite film based devices increased as MEH‐PPV content increased. Furthermore, white emission blue shifted with increasing spin‐rate of thin film coating and applied voltage. Low turn‐on voltage, high current density, and high brightness were obtained for the device fabricating with light emitting layer coating with high spin‐rate. Moreover, low current efficiency was obtained for the PLED with a thinner light‐emitting layer. A white emission CIE (0.28,0.34) was obtained for PTOA‐MEH‐PPV based white PLED. White PLED brightness and efficiency can be as high as 700 cd/m² and 0.78 cd/A, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Enhancement of electroluminescence properties of red diketopyrrolopyrrole-doped copolymers by oxadiazole and carbazole units as pendants

Two novel diketopyrrolopyrrole (DPP)-based copolymers P1-2 were prepared by doping red emitting DPP monomer (1 mol%) into benzothiadiazole, alkoxybenzene and 9,9-dialkylfluorene-based copolymers through base-free Suzuki polymerization. P1 contained the pendants of electron-transport oxadiazole and hole-transport carbazole, but P2 did not contain them. P1 had higher glass transition temperature than P2. The electroluminescence (EL) devices of P1 and P2 (ITO/PEDOT:PSS/polymer/CsF/Al) exhibited red emission with external quantum efficiency of 0.63% and 0.18%, and with brightness of 2681 and 885 cd/m², respectively. The results show that the EL properties of P1 are much better than that of P2 due to the introduction of oxadiazole and carbazole as the pendants. The pendants could restrain aggregation which might induce fluorescence quenching and are of benefit to keep high charge mobility. The efficient energy transfer existed among the pendants, polymer backbone and DPP unit. These factors should be responsible for the higher EL performance of P1.     

Synthesis and electroluminescence properties of fluorene-co-diketopyrrolopyrrole-co-phenothiazine polymers

A series of fluorene-co-diketopyrrolopyrrole(DPP)-co-phenothiazine polymers, named as Flu-DPP-Phen, were synthesized by a palladium-catalyzed Suzuki coupling reaction with different feed ratios among 9,9-dihexylfluorene-2,7-bis(trimethylene boronate), 2,5-dioctyl-3,6-bis(4-bromophenyl)pyrrolo[3,4-c]pyrrole-1,4-dione, and 3,7-dibromo-10-octylphenothiazine. Their chemical structures and compositions were confirmed by ¹H NMR and elemental analysis. These terpolymers were found to be thermally stable and readily soluble in common organic solvents. Absorption and photoluminescence (PL) properties of Flu-DPP-Phen exhibit regular change with increasing of DPP contents in the terpolymers. Electroluminescence (EL) properties of all the terpolymers were characterized with the device configurations of ITO/PEDOT/terpolymer/Ba/Al and ITO/PEDOT/PVK/terpolymer/Ba/Al. Owing to exciton confinement on the narrow band gap DPP unit, the emission of fluorene segments is quenched completely with very low content of DPP (0.2 mol%). The EL spectra of all the terpolymers show exclusive long-wavelength emission originating from DPP units, which implied that the energy transfer in the terpolymer is very efficient. EL colors of the terpolymers vary from orange to red, the maximum emission is gradually red-shifted from 582 nm to 600 nm. The best EL performance was achieved by Flu-DPP-Phen(50:30:20) with maximum external quantum efficiency (EQE) of 0.25% and maximum brightness of 259 cd/m² in the device configuration of ITO/PEDOT/PVK/terpolymer/Ba/Al. The preliminary EL results proved that DPP units could effectively improve the electron affinity, and phenothiazine units could significantly enhance the hole injection ability, which resulted in the remarkable improvement of EQE.     

A highly soluble blue light emitting copolymer of anthracene and dialkyloxyl benzene prepared by oxidative-coupling reaction

A new kind of soluble copolymers incorporated anthracene and dialkyloxyl benzene moieties into main chain have been prepared by oxidative-coupling copolymerization. They were characterized by FT-IR, ¹H NMR, UV-Vis, GPC, X-ray, thermogrametric analysis and fluorescence spectroscopy. The copolymers are amorphous and show excellent solubility in common organic solvents, such as chloroform. Thermogrametric analysis of the copolymers revealed that they have good stability with the onset decomposition temperature above 330 °C. The fluorescence spectra of the copolymers in solid state film display blue light emitting properties with the maximum at 468 nm.     

Synthesis and properties of fluorenyl–pyridinyl alternatingcopolymers for light‐emitting diodes

A novel series of well‐defined alternating poly[2,7‐(9,9‐di(2‐ethylhexyl)fluorenyl)‐alt‐pyridinyl] (PDEHFP) copolymers were synthesized using palladium(0)‐catalyzed Suzuki coupling reaction in high yields. These polymers were characterized using ¹H NMR, UV‐visible and fluorescence spectroscopies, gel permeation chromatography, thermal analysis and cyclic voltammetry. The optical properties of the copolymers, including photoluminescence (PL) and electroluminescence (EL), were studied. The difference in linkage position of pyridinyl units in the polymer backbone has significant effects on the electronic and optical properties of polymers in solution and in film state. Meta‐linkage (3,5‐ and 2,6‐linkage) of pyridinyl units in the polymer backbone is more favorable for pure blue emission and prevention of aggregation of polymer chains. PDEHFPs with 2,6‐ and 3,5‐linkage of pyridinyl units have relatively high PL efficiency of 37 and 44% in the film state. In comparison with homopolymer PDEHF, the copolymers with pyridinyl units possess low lowest unoccupied molecular orbital energy levels for easy electron injection from a cathode. Strong EL is observed and light‐emitting diodes (LEDs) exhibit typical rectifying characteristics. The emission intensity starts to increase at around 12 V. The emission peak wavelengths of the polymers roughly coincide with those of PL. This series of fluorene–pyridine‐based alternating copolymers seem to be candidates for polymeric LEDs. © 2013 Society of Chemical Industry     

Synthesis and characterization of ortho-twisted asymmetric anthracene derivatives for blue organic light emitting diodes (OLEDs)

New ortho-twisted asymmetric anthracene derivatives have been synthesized and characterized. The anthracene derivatives show good thermal stability with high glass transition temperatures and a pure blue emission with a narrow full width at half maximum in a film state (λ_max = 454 nm with 71 nm for 2-(2-methylnaphtathalene-1-yl)-9,10-di(naphthalene-2-yl)anthracene and λ_max = 445 nm with 60 nm for 2-(biphenyl-2-yl)-9,10-di(naphthalene-2-yl)anthracene). A multi-layered device using 2-(2-methylnaphtathalene-1-yl)-9,10-di(naphthalene-2-yl)anthracene as an emitting material exhibits a maximum quantum efficiency of 3.61% (power efficiency of 2.15 lm/W, current efficiency of 3.55 cd/A) and blue Commission Internationale de l’Eclairage chromaticity coordinates (x = 0.15, y = 0.13). A fabricated device using 2-(biphenyl-2-yl)-9,10-di(naphthalene-2-yl)anthracene as an emitting material exhibits a maximum quantum efficiency of 3.7% (power efficiency of 2.11 lm/W, current efficiency of 3.55 cd/A) and a blue Commission Internationale de l’Eclairage chromaticity coordinates (x = 0.15, y = 0.12).     

New fluorene–pyrazino[2,3‐g]quinoxaline‐conjugated copolymers: Synthesis,optoelectronic properties,and electroluminescence characteristics

New donor–acceptor conjugated copolymers called poly}2,7‐(9,9′‐dihexylfluorene)‐co‐5,10‐[pyrazino(2,3‐g)quinoxaline]{s or PFPQs [where F represents the 2,7‐(9,9′‐dihexylfluorene) moiety and PQ represents the 5,10‐(pyrazino[2,3‐g]quinoxaline) moiety], synthesized by the palladium‐catalyzed Suzuki coupling reaction, are reported. The PQ contents in the PFPQ copolymers were 0.3, 1, 5, and 50 mol %, and the resulting copolymers were named PFPQ0.3, PFPQ01, PFPQ05, and PFPQ50, respectively. Absorption spectra showed a progressive redshift as the PQ acceptor content increased. The relatively small optical band gap of 2.08 eV for PFPQ50 suggested strong intramolecular charge transfer (ICT) between the F and PQ moieties. The photoluminescence emission peaks of the PFPQ copolymer films also exhibited a large redshift with enhanced PQ contents, ranging from 551 nm for PFPQ0.3 to 592 nm for PFPQ50. However, the PFPQ copolymer based electroluminescence (EL) devices showed poor device performances probably due to the strong confinement of the electrons in the PQ moiety or significant ICT. This problem was resolved with a binary blend of poly[2,7‐(9,9‐dihexylfluorene)] (PF) and PFPQ with a volume ratio of 95/5 (BPQ05). Multiple emission peaks were observed at 421, 444, 480, 516, and 567 nm in the BPQ05‐based EL devices because the low PQ content led to incomplete energy transfer. The Commission Internationale de L'Eclairage 1931 coordinates of the BPQ05‐based EL device were (0.31, 0.32), which were very close to the standard white emission of (0.33, 0.33). Furthermore, the maximum luminescence intensity and luminescence yield were 524 cd/m² and 0.33 cd/A, respectively. This study suggested that a pure white light emission was achieved with the PFPQ copolymers or PF/PFPQ blends through the control of the energy transfer between F and PQ. Such PFPQ copolymers or PF/PFPQ blends would be interesting for electronic and optoelectronic devices. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Electrochemistry and electron transport properties of copolymers of electron deficient fluorenes with thiophene

Copolymers of fluoren-9-one and (fluoren-9-ylidene)malononitrile with thiophene have been prepared by the electrochemical polymerization of 2-(2-thienyl)fluoren-9-one, 2,7-di(2-thienyl)fluoren-9-one, and (2,7-di(2-thienyl)fluoren-9-ylidene)malononitrile. 2-(2-Thienyl)fluoren-9-one gave polymer films with low conjugation lengths, indicating poorly defined coupling, while both monomers with two terminal thiophenes gave high quality copolymers. Poly-[2,7-di(2-thienyl)fluoren-9-one] was the most easily p-doped material, and gave the highest p-type conductivity of ca. 0.4 mS cm⁻¹. In contrast poly-[(2,7-di(2-thienyl)fluoren-9-ylidene)malononitrile] was more easily reduced by over 0.5 V (formal potential = −0.60 V versus Ag/AgCl), and exhibited the higher n-type conductivity of ca. 6 μS cm⁻¹. Comparisons between the three copolymers reveal differences in the mechanisms of p-type and n-type conduction, with the former dominated by hole transport along the polymer chains and the latter involving electron hopping between localized sites.     

Synthesis,characterization, and optoelectronic properties of two new polyfluorenes/poly(p‐phenylenevinylene)s copolymers

Two novel copolymers of polyfluorenes/poly(p‐phenylenevinylene)s copolymers with p‐tert‐butyl‐phenylenemethylene groups in the C‐9 position of alternating fluorene unit, poly[1,4‐(2,5‐dibutyloxyl)‐phenyleneviny lene‐alt‐9‐(p‐tert‐butyl‐phenylenemethylene)fluorene] and poly[1,4‐(2,5‐dioctyloxyl)‐phenylenevinylene‐alt‐9‐(p‐tert‐butyl‐phenylenemethylene)fluorine], have been synthesized via the Heck polycondensation reaction. The synthesized polymers were characterized by FTIR, NMR, DSC, TGA, UV–vis, and PL spectra. The polymers showed high glass transition temperatures and good thermal stability. A polymer light‐emitting diode with the configuration ITO/PEDOT:PSS/P2/Ca/Al has been fabricated. The device emitted a yellow light with a peak wavelength of 578 nm similar to the PL spectra of the copolymer film. A maximal luminance of 534 cd/m² was obtained at a driving voltage of 24.5 V. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3955–3962, 2006     

Carbazole/fluorene copolymers with dimesitylboron pendants for blue light-emitting diodes

A series of random and alternating carbazole/fluorene copolymers with various dimesitylboron-containing carbazole derivative contents were synthesized by Suzuki polymerization for use as a light-emitting layer in blue light-emitting diodes. Two carbazole derivatives, CzPhB and CzPhThB consisted of a carbazoyl group as the donor and a dimesitylboron group as the acceptor group, separated by phenyl and phenyl-thiophene groups π-conjugated systems, respectively. The copolymers exhibited good thermal stability and blue emission in both solution and the solid state. Moreover, the CzPhB/fluorene and CzPhThB/fluorene copolymers exhibited a higher PL quantum efficiency than the fluorene-based homopolymer (POF). Higher brightness and larger current efficiency were observed for the CzPhB/fluorene and CzPhThB/fluorene copolymer-based devices compared to the POF-based device. Additionally, the CzPhThB/fluorene copolymer-based devices had better EL performances than the CzPhB/fluorene copolymer-based devices. The turn-on voltage, maximal brightness, and highest luminescence efficiency of the carbazole/fluorene copolymer-based devices were found to be 4.5-8.5 V, 436 cd/m², and 0.51 cd/A, respectively.     

Synthesis and properties of fluorene‐based polyimide adhesives

Five kinds of fluorene‐based polyimides (PIs) based on 4,4′‐oxydiphthalicanhydride (ODPA), 9,9′‐bis(4‐aminophenyl)fluorene (BAFL), and 3,4′‐diaminodiphenyl ether (3,4′‐ODA) were synthesized through two‐step method. The partially or fully imidized PI films were cast from poly(amic acid) (PAA) solution and were imidized by far‐infrared radiation at various temperatures. The degree of imidization was characterized by FT‐IR and TGA. The fully imidized PI films were characterized by DMTA, TGA, and tensile tests. The partially imidized PI films were adhered to stainless steel plates for preparing the single lap joints. Lap shear strength (LSS) at room temperature was measured to compare the adhesive strength of single lap joint. Fractured surfaces were analyzed using scanning electron microscopy (SEM). The effects of fluorene content on thermal, tensile, and adhesion properties of PIs were elaborately studied. The results showed that PI films exhibited high glass transition temperature (T_g), good thermalplasticity, and thermal stability. The LSS of PIs increased abruptly with the incorporation of fluorene groups. The LSS of PI‐50/50 was the highest, which was 22.3 MPa. The LSS of PI‐50/50 was also measured at high temperature to investigate the thermal resistance of fluorene‐based PI adhesive. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.     

Synthesis of oxadiazole‐based polymers containing a carbazole–vinylene or fluorene–vinylene group and their hole‐injection/transport behavior in light‐emitting diodes

A series of conjugated (poly{N‐(2‐ethylhexyl)‐3,6‐carbazole–vinylene‐alt‐[(2,5‐bisphenyl)‐1,3,4‐oxadiazole]}) and nonconjugated (poly{N‐(2‐ethylhexyl)‐3,6‐carbazole–vinylene‐alt‐[(2,5‐bisphenol)‐1,3,4‐oxadiazole]}) and poly{9,9‐dihexyl‐2,7‐fluorene–vinylene‐alt‐[(2,5‐bisphenol)‐1,3,4‐oxadiazole]}) polymers containing oxadiazole and carbazole or fluorene moieties in the polymer backbone were synthesized with a multiple‐step procedure. The properties of the polymers, including the photophysical and electrochemical characteristics, could be fine‐tuned by adjustment of the components or structures in the polymer chains. The polymers were used to examine the hole‐injection/transport behavior as hole‐injection/hole‐transport layers in double‐layer indium tin oxide (ITO)/polymer/aluminum tris(8‐hydroxyquinoline)/LiF/Al devices by the determination of their energy levels. The effects of the polymers in these devices on the charge‐transport behavior were compared with a control device fabricated with poly(ethylenedioxythiophene) (PEDOT)–poly(styrene sulfonate) (PSS). Devices containing the synthesized polymers showed comparable adhesion to the ITO anode and good hole‐injection/transport performance. In addition, they exhibited higher electroluminescence over an identical range of current densities than the control device. This was attributed to the prevention of radiative exciton quenching caused by the PEDOT–PSS interfaces and the improvement of electron/exciton blocking due to the higher electron affinity of the synthesized polymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of carbazole-based hyperbranched conjugated polymers

Carbazole-based novel hyperbranched conjugated polymers linked with triphenylamine and benzene moieties were synthesized by Sonogashira coupling polycondensation of N-octadecyl- and N-octyl-3,6-diethynylcarbazoles with tris(4-iodophenyl)amine and 1,3,5-tribromobenzene. Solvent-soluble polymers with number-average molecular weights in the range of 3500-21,000 were obtained in 48-66% yields. The UV-vis absorption bands of the polymers were red-shifted compared to that of carbazole, indicating the extension of conjugation length. The polymers emitted blue-green fluorescence with high quantum yields up to 67% in CHCl₃. Poly(1/3) containing triphenylamine units emits visible light and shows unique solvatochromism. The polymers were electrochemically redox-active.     

Synthesis of highly conjugated poly(3,9-carbazolyleneethynylenearylene)s emitting variously colored fluorescence

Novel conjugated polymers P1–P7 containing 3,9-linked carbazole units in the main chain were synthesized by the polycondensation of 3-ethynyl-9-(4-ethynylphenyl)carbazole (EEPCz) and dihaloarenes, and their optical and electrical properties were studied. Polymers with weight-average molecular weights of 4100–48,000 were obtained in 24–92% yields by the Sonogashira coupling polycondensation in tetrahydrofuran (THF)/Et₃N at 30 or 50 °C for 48 h. All the polymers absorbed light around 350 nm. The polymers with electron-accepter units exhibited absorption bands originating from charge transfer. The polymers except the one containing azobenzenes emitted variously colored fluorescence with moderate quantum yields upon excitation at the absorption maxima. P1–P3 were oxidized around 0.6 V, and then reduced around 0.5 V. The conductivity of P3 was 1.1 × 10⁻¹⁴ S/cm at 10³ V/cm.     

Synthesis and solution properties of temperature‐sensitive copolymers based on NIPAM

A kind of temperature‐sensitive water‐soluble polymers P(NIPAM‐HEMA‐AM) of N‐isopropylacrylamide (NIPAM), hydroxyethyl methacrylate (HEMA) and acrylamide (AM) were synthesized by free radical aqueous solution copolymerization. The polymers were characterized by Fourier transform infrared spectrum (FTIR) method. Solution properties, such as the influences of monomer ratios and additives on the low critical soluble temperature (LCST) of the polymer solutions as well as the viscosity‐temperature properties were studied. The results show that the polymer concentrations have no significant influence on the LCST of polymer solutions. The incorporation of HEMA units leads to a lower LCST, while AM units to a higher LCST. The additions of small molecules such as salt and surfactant also have significant effect on the LCST, the addition of NaCl decreases the LCST, while the addition of sodium dodecylbenzenesulfonate (SDBS) increases the LCST. The apparent viscosity of polymer solutions depends on temperature. The 1.5 wt % aqueous solutions of P(NIPAM‐HEMA‐AM) exhibits good thermo‐thickening behavior over 55°C, whereas the 0.8 wt % aqueous solutions do not show this behavior during the heating process. The aqueous solutions of P(NIPAM‐HEMA‐AM) are viscoelastic fluids, and the viscoelasticities mainly depend on temperature. Both the storage modulus (G') and loss modulus (G'') of 1.5 wt % polymer solutions increase with temperature. Over 55°C, G' exceeds G'', and the polymer solutions are elasticity‐dominated. In contrast, below 55°C, G'' is larger than G', and the polymer solutions are viscosity‐dominated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Enhancing the electroluminescence performances of blue polymer light emitting devices via carriers transporting materials incorporation

A series of polymer light emitting devices (PLEDs) based on the composite films of N‐arylbenzimidazoles trimer (TPBI), poly (n‐vinylcarbazole) (PVK), and a triarylaminooxadiazole‐containing tetraphenylsilane light emitting polymer (PTOA) were investigated. Electroluminescence (EL) performance is enhanced with doped TPBI into the light‐emitting layer for the PTOA‐based devices. A deep blue emission (Commission Internationale de L'Eclairage (CIE_x,y) corodinates (0.16,0.06)) is obtained for the TPBI‐PTOA‐based device. Brightness and current efficiency of the TPBI‐PTOA‐based device can be as high as 961 cd/m² and 1.85 cd/A, respectively. The EL performances of TPBI‐PTOA composite film‐based devices are further enhanced by inserting a TPBI layer into the light emitting layer and cathode interface for a better electron and hole charge balance. Doping TPBI into the light‐emitting layer of PVK‐PTOA is not favorable for enhanced EL performances. Brightness and current efficiency reduced with increasing TPBI content for the TPBI‐PVK‐PTOA‐based devices. Similar results are obtained for devices based on the TPBI‐PVK‐PTOA/TPBI bi‐layer composite solid film. Morphology and charge balance effects on EL performances of TPBI‐PTOA and TPBI‐PVK‐PTOA composite films based PLEDs are discussed in detail. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and properties of novel deep red‐emitting copolymers based on a poly(p‐phenylenevinylene) derivative

A series of novel copolymers based on a poly(p‐phenylenevinylene) (PPV) derivative with different content of narrow band‐gap unit 2,1,3‐benzoselenadiazolevinylene (BSeV) was prepared via Stille coupling reaction. The copolymers emit light from deep red to near‐infrared (NIR) depending on BSeV content in the copolymers. The electroluminescence (EL) emission peaked at 752 nm for the copolymer with the content of 30 mol % BSeV is among the longest reported so far for the PPV polymers. The best device performance is observed for the copolymer with 1 mol % BSeV content with external quantum efficiency (QE_ext) of 0.26% and CIE coordinate 0.65, 0.34 (x,y). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4321–4327, 2006     

Incorporation of benzothiadiazole moiety at junction of polyfluorene–polytriarylamime block copolymer for effective color tuning in organic light emitting diode

Block copolymer consisting of polyfluorene and polytriarylamine with benzothiadiazole moiety at the junction is prepared in order to obtain an orange emitting polymer via Suzuki‐Miyaura followed by Buchwald‐Hartwig coupling reactions. Electroluminescent device fabricated with resulting block copolymer exhibit only orange emission, although slight blue emission is observed in the fluorescent spectrum for the thin film, indicating that benzothiadiazole part plays a role of an effective trap site. Devices based on polyfluorene homopolymer doped with block copolymer (10 wt %) or an orange emitting model compound at the corresponding content of benzotiadiazole unit are also fabricated. The device with the model compound exhibits orange emission with Commission Internationale de l'Éclairage (CIE) coordinate of (0.58, 0.42), whereas that with block copolymer pale orange with the coordinate of (0.44, 0.38). This fact is probably due to the preferential distribution of block copolymer at the vicinity of anode via hydrophilic interaction of trioxyethylene side chains with poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45393.