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1.
Nanotechnology ; 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-32150735

RESUMO

Commercially available Jeffamines (polyetheramine) with average molecular weights of 2000 and 3000 g mol-1; one (M2005), two (D2000), and three (T3000) primary amino groups end-capping on the polyether backbone; and propylene oxide (PO) and ethylene oxide (EO) functionality were explored as additives for application in MAPbI3 perovskite solar cells (PSCs). The results indicated that the embedding of Jeffamine additives effectively passivates the defects in the grain boundaries of perovskite through the coordination bonding between the nitrogen atom and the uncoordinated lead ion of perovskite. We fabricated p-i-n PSC devices with the structure of glass/indium tin oxide (ITO)/NiOx/CH3NH3PbI3 (with and without Jeffamine)/PC61BM/BCP/Ag. We observed the interaction between the Jeffamine and perovskites. This interaction led to increased lifetimes of the carriers of perovskite, which enabled the construction of high-performance p-i-n PSCs. For the Jeffamine-D2000-derived device, we observed an increase in the power conversion efficiency from 14.5% to 16.8% relative to the control device. Furthermore, the mechanical properties of the perovskite films were studied. The interaction between the additive and perovskite reinforced the flexibility of the thin film, which may pave the way for stretchable optoelectronics.

2.
ACS Appl Mater Interfaces ; 9(33): 27853-27862, 2017 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-28762269

RESUMO

In this study, a new hybrid electrode featuring a high gauge factor of >30, decent stretchability (100% of the original conductivity can be retained after 50 cycles of stretching under a 20% strain without prestrain treatment), high transmittance (>70%) across 400-900 nm, and a good sheet resistance (<50 Ω sq-1) was successfully exploited. These superior properties were revealed to originate from the reversible phase separation endowed by the nanogranular-like morphology formed in Ag. Owing to such discrete nanomorphology, the free volume within this Ag electrode is susceptible to the applied tensile strain and the ensuing change in conductivity enables the realization of an efficient strain sensor. Besides, a representative PTB7-th:PC71BM organic photovoltaic (OPV) using this electrode (with the assistance of a wrinkled scaffold to reinforce the stretchability of the active layer) can exhibit a power-conversion efficiency (PCE) of 6% along with high deformability, for which 75% of its original PCE is retained after 50 cycles of stretching under a 20% strain. Meanwhile, a representative all-polymer OPV consisting of a PTB7-th:N2200 blend, in which the N2200 has a better mechanical stretchability than that of PC71BM, can maintain over 96% of its original PCE after 50 cycles of stretching (under a 20% strain) without employing the wrinkled scaffold. Such promising performance in stretchable OPVs is among the state-of-the-art results reported to date.

3.
Polymers (Basel) ; 9(4)2017 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-30970816

RESUMO

Novel multifunctional switchable chemosensors based on fluorescent electrospun (ES) nanofibers with sensitivity toward magnetism, temperature, and mercury ions (Hg2+) were prepared using blends of poly(N-isopropylacrylamide)-co-(N-methylolacrylamide)-co-(Acrylic acid), the fluorescent probe 1-benzoyl-3-[2-(2-allyl-1,3-dioxo-2,3-dihydro-1Hbenzo[de]isoquinolin-6-ylamino)-ethyl]-thiourea (BNPTU), and magnetite nanoparticles (NPs), and a single-capillary spinneret. The moieties of N-isopropylacrylamide, N-methylolacrylamide, acrylic acid, BNPTU, and Iron oxide (Fe3O4) NPs were designed to provide thermoresponsiveness, chemical cross-linking, Fe3O4 NPs dispersion, Hg2+ sensing, and magnetism, respectively. The prepared nanofibers exhibited ultrasensitivity to Hg2+ (as low as 10-3 M) because of an 80-nm blueshift of the emission maximum (from green to blue) and 1.6-fold enhancement of the emission intensity, as well as substantial volume (or hydrophilic to hydrophobic) changes between 30 and 60 °C, attributed to the low critical solution temperature of the thermoresponsive N-isopropylacrylamide moiety. Such temperature-dependent variations in the presence of Hg2+ engendered distinct on⁻off switching of photoluminescence. The magnetic ES nanofibers can be collected using a magnet rather than being extracted through alternative methods. The results indicate that the prepared multifunctional fluorescent ES nanofibrous membranes can be used as naked eye sensors and have the potential for application in multifunctional environmental sensing devices for detecting metal ions, temperature, and magnetism as well as for water purification sensing filters.

4.
Polymers (Basel) ; 9(8)2017 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-30971016

RESUMO

In this study, we synthesized amphiphilic poly(2,7⁻(9,9⁻dioctylfluorene))⁻block⁻N,N⁻(diisopropylamino)ethyl methacrylate (POF⁻b⁻PDPMAEMA) rod-coil diblock copolymers by atom transfer radical polymerization (ATRP). The structure and multifunctional sensing properties of these copolymers were also investigated. The POF rod segment length of 10 was fixed and the PDPAEMA coil segment lengths of 90 and 197 were changed, respectively. The micellar aggregates of POF10⁻b⁻PDPAEMA90 rod-coil diblock copolymer in water showed a reversible shape transition from cylinder bundles to spheres when the temperature was changed from 20 to 80 °C or the pH was changed from 11 to 2. The atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements indicated that the temperature had also an obvious influence on the micelle size. In addition, since POF10⁻b⁻PDPAEMA90 had a lower critical solution temperature, its photoluminescence (PL) intensity in water is thermoreversible. The PL spectra showed that the POF⁻b⁻PDPAEMA copolymer had a reversible on/off profile at elevated temperatures, and thus could be used as an on/off fluorescent indicator for temperature or pH. The fluorescence intensity distribution of pH switched from "off⁻on" to "on⁻off" as the temperature increased. These results showed that the POF⁻b⁻PDPAEMA copolymer has a potential application for temperature and pH sensing materials.

5.
Polymers (Basel) ; 9(11)2017 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-30965936

RESUMO

In this study, chemical treatment (CT; oxidation⁻reduction method) and physical treatment (HP; hot-pressing methods) were applied to improve the performance of silver nanowire (AgNW)-derived electrodes on a glass or flexible polyethylene terephthalate (PET) substrate. The four-point probe method, UV-Vis spectroscopy and scanning electron microscopy (SEM) were used to measure the properties of AgNW electrodes and compare them with those of indium tin oxide (ITO) electrodes for exploring the possibility of using CT- and HP-based AgNW electrodes for polymer solar cell (PSC) applications. Using the CT or HP method, the sheet resistance of electrodes decreased to lower than 40 Ω sq-1 with an average high transmittance of more than 80%. Furthermore, HP reduced the surface roughness of AgNWs, which solved the inter-electrode short circuiting problem for devices. We studied the performance of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) and zinc oxide-based PSC devices. The power conversion efficiency of HP-AgNW-derived poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl] (PTB7-Th):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) devices was 7.83%, which was slightly lower than the performance of the device using ITO (8.03%) as a substrate. After a bend test (100 times) at a 2-cm curvature radius, the efficiency of AgNW/PET-derived PSCs was more than 70%. The performance of PSCs made with AgNWs and ITO electrodes is comparable, but the cost of using AgNWs for electrodes is much lower; therefore, HP-derived AgNWs demonstrate great potential for optoelectronic applications.

6.
Nanoscale Res Lett ; 11(1): 488, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27822910

RESUMO

The organic material soluble polyimide (PI) and organic-inorganic hybrid PI-barium titanate (BaTiO3) nanoparticle dielectric materials (IBX, where X is the concentration of BaTiO3 nanoparticles in a PI matrix) were successfully synthesized through a sol-gel process. The effects of various BaTiO3 contents on the hybrid film performance and performance optimization were investigated. Furthermore, pentacene-based organic thin film transistors (OTFTs) with PI-BaTiO3/polymethylmethacrylate or cyclic olefin copolymer (COC)-modified gate dielectrics were fabricated and examined. The hybrid materials showed effective dispersion of BaTiO3 nanoparticles in the PI matrix and favorable thermal properties. X-ray diffraction patterns revealed that the BaTiO3 nanoparticles had a perovskite structure. The hybrid films exhibited high formability and planarity. The IBX hybrid dielectric films exhibited tunable insulating properties such as the dielectric constant value and capacitance in ranges of 4.0-8.6 and 9.2-17.5 nF cm-2, respectively. Adding the modified layer caused the decrease of dielectric constant values and capacitances. The modified dielectric layer without cross-linking displayed a hydrophobic surface. The electrical characteristics of the pentacene-based OTFTs were enhanced after the surface modification. The optimal condition for the dielectric layer was 10 wt% hybrid film with the COC-modified layer; moreover, the device exhibited a threshold voltage of 0.12 V, field-effect mobility of 4.32 × 10-1 cm2 V-1 s-1, and on/off current of 8.4 × 107.

7.
Nanoscale Res Lett ; 10(1): 446, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26577390

RESUMO

A two-dimensional nanostructure of molybdenum disulfide (MoS2) thin film exposed layered nanosheet was prepared by a low-temperature thermally reduced (TR) method on a fluorine-doped tin oxide (FTO) glass substrate as a platinum (Pt)-free and highly electrocatalytic counter electrode (CE) for dye-sensitized solar cells (DSSCs). Thermogravimetric analysis (TGA) results show that the MoS2 sulfidization temperature was approximately 300 °C. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) indicate that the stoichiometry and crystallization of MoS2 were more complete at higher temperatures; however, these temperatures reduce the number of edge-plane active sites in the short-range-order nanostructure. Accordingly, the DSSCs with 300 °C annealed TR-MoS2 CE exhibited an excellent photovoltaic conversion efficiency (PCE) of 6.351 %, up to 91.7 % of which is obtained using the conventional TD-Pt CE (PCE = 6.929 %). The temperature of thermal reaction and the molar ratio of reaction precursors were found to significantly influence the resulting stoichiometry and crystallization of MoS2 nanosheets, thus affecting DSSCs' performance.

8.
Nanoscale ; 6(19): 11403-10, 2014 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-25148554

RESUMO

In this study we used solution-processable crystalline TiO2 nanoparticles as an interfacial modified layer between the active layer and aluminum cathode to fabricate CH3NH3PbI3/PCBM-based planar heterojunction perovskite photovoltaic (PPV) devices. We optimized the performance of the PPV device prepared without TiO2 by varying the preheating temperature of the indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) (PEDOT) substrate, obtaining a power conversion efficiency (PCE) of 6.3% under simulated AM 1.5 G irradiation (100 mW cm(-2)). After incorporating the TiO2 layer, we obtained a much higher PCE of 7.0%. The TiO2-containing PPV device exhibited extremely high stability (retaining ∼96% of its PCE after 1000 h) under long-term storage in a dark N2-filled glove box; the unencapsulated device retained approximately 80% of its original efficiency (T80) after 1 week under ambient conditions (ISOS-D-1; defined as 23 °C/50% RH). In contrast, the normal device was sensitive to ambient conditions with a value of T80 at only 3 h. We attributed the improved device performance (PCE, stability) to the enhanced electron transporting, hole blocking, and barrier properties arising from the presence of the TiO2 layer.

9.
Nanoscale ; 6(17): 10281-8, 2014 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-25065461

RESUMO

In this paper, we describe relationships between the morphologies and the power conversion efficiencies (PCE) of perovskite photovoltaics having a conventional p-i-n heterojunction structure, indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS)/CH(3)NH(3)PbI(3-x)Cl(x)/PC(61)BM/Al. The PCE of such a device is highly dependent on the morphology of the perovskite film, which is governed by the concentrations of its precursors and the annealing conditions. A two-step annealing process allowed sufficient crystallization of the perovskite material, with a high coverage at a high precursor concentration. Relative to the device prepared using a one-step process (90 °C for 30 min), we observed a 60% increase in PCE for this optimized device. The corresponding devices exhibited extremely high stability after long-term storage (>1368 h) in the dark in a N2-filled glove box, with consistently high PCEs (AM 1.5 G, 100 mW cm(-2)) of up to 9.1%.

10.
J Nanosci Nanotechnol ; 10(8): 5354-8, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21125897

RESUMO

In this study, polythiophene based rod-coil block copolymers (P3HT)47-b-(PMSMA)34 are synthesized by atom transfer radical polymerization (ATRP). The effects of altering the mix of solvent and processing temperature on the morphologies and photophysical properties of the block copolymers in both solution and solid state are investigated. The chemical structure of the prepared block copolymers is confirmed by NMR and FTIR analysis. TEM results show that different morphologies of aggregates can be obtained by varying the toluene/methanol ratios. Such aggregation leads to a significant red shift on the optical absorption and photoluminescence spectra of the P3HT-b-PMSMA in mixed solvents. The results of AFM, UV-Vis, and PL show that the morphologies and photophysical properties of P3HT-b-PMSMA films are also significantly affected by the curing temperature. Blue shifts on the optical absorption and photoluminescence spectra are observed upon increasing the curing temperature.

11.
J Nanosci Nanotechnol ; 10(8): 5359-63, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21125898

RESUMO

In this study, poly(4,4-(hexafluoroisopropylidenediphthalic anhydride)-co-oxydianiline) (6FDA-ODA) and a novel core-shell nanoparticle consisting of a core (SnO2/TiO2) and a shell (ZrO2/Sb2O3) with the composition (SnO2:TiO2:ZrO2:Sb2O3 = 18:5:3:4) were used to prepare polyimide/nanoparticles hybrid thin films. The resultant hybrid thin films were investigated by FTIR, TGA, DSC, TEM, SEM, AFM, alpha-step, UV-Vis, and n&k analyses. The results show that the prepared hybrid thin films had a good thermal stability. The size of nanoparticles was effectively controlled in the range of 8-10 nm in the hybrid thin films. These nanoparticles were evenly distributed across the hybrid thin films and no phase separation occurred. In terms of the optical properties, the prepared hybrid thin films had good transparency in the range of visible light. The cutoff wavelength had a blue shift as the content of the nanoparticles increased. The refractive index of prepared hybrid thin films increased with corresponding increases in nanoparticle content. Moreover, the prepared polyimide/core-shell nanoparticle hybrid thin films displayed excellent film formability and planarity.

12.
J Nanosci Nanotechnol ; 10(8): 5364-8, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21125899

RESUMO

In this study, poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films were prepared from various acrylic monomers (MMA and EDMA/TMPTA), lanthanide metal complexes (EuL3 x 2H2O, L = pyridine carboxylic acid), and monodispersed colloidal silica with a coupling agent, 3-(trimethoxysilyl)propyl methacrylate (MSMA). It is a combination of the sol-gel reaction, thermal polymerization, and spin coating. The silica content in the hybrid thin films is fixed at 20 wt%, and the EuL3 x 2H2O content is varied from 0.01 g to 0.07 g. FTIR and EA analysis confirms the chemical structure of the prepared EuL3 x 2H2O and poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films. UV-Vis spectra and n&k analysis shows that the hybrid thin film has good transparency in visible light. The refractive index of hybrid thin films can be effectively controlled through the EuL3 x 2H2O content. The PL spectra shows that the strongest emission peak occurs at 615 nm and the emission intensity increases to the peak maximum at an EuL3 x 2H2O content of 0.05 g. Both TGA and PL analysis show that the prepared hybrid thin films from the crosslinked acrylic polymer moiety have much better film uniformity, thermal stability, and fluorescence properties. The TEM diagram shows that the MSMA/SiO2/EuL3 x 2H2O particles with a size 15-20 nm are well dispersed in the reaction solution. The SEM diagram shows that the particle distribution in the prepared hybrid thin films is uniform and no phase separation is observed. Finally, AFM analysis indicates that the prepared hybrid thin films have an excellent surface planarity.

13.
J Nanosci Nanotechnol ; 10(7): 4573-80, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21128459

RESUMO

Nanoporous silica films were prepared through the templating of amphiphilic block copolymer, poly(styrene-2-vinyl pyridine) (PS-b-P2VP), and monodispersed colloidal silica nanoparticles. The experimental and theoretical studies suggested that the intermolecular hydrogen bonding existes between the colloidal silica nanoparticles and PS-b-P2VP. The effects of the loading ratio and P2VP chain length on the morphology and properties of the prepared nanoporous silica films were investigated. TEM and AFM studies showed that the uniform pore size could be achieved and the pore size increased with increasing porogen loading. The refractive index and dielectric constant of the prepared nanoporous films decreased with an increase in PS-b-P2VP loading. On the other hand, the porosity increased with an increasing PS-b-P2VP loading. This study demonstrated a methodology to control pore morphology and properties of the nanoporous silica films through the templating of PS-b-P2VP.

14.
J Nanosci Nanotechnol ; 9(7): 4040-7, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19916406

RESUMO

In this study, poly(acrylic)/SiO2/EuL3 x 2H2O hybrid thin films were prepared from various acrylic monomers (MMA and EDMA/TMPTA), lanthanide metal complexs (EuL3 x 2H2O, L = pyridine carboxylic acid), and monodispersed colloidal silica with a coupling agent, 3-(trimethoxysilyl)propyl methacrylate (MSMA). It was a combination of the sol-gel reaction, thermal polymerization, and spin coating. The EuL3 x 2H2O content in the hybrid thin films was fixed at 0.05 g and silica content was varied from 10 to 50 wt%. TEM results showed that both SiO2 and EuL3 x 2H2O were well dispersed in the hybrid thin films without aggregation. PL spectra showed the unique emission of Eu3+. The addition of SiO2 made the compounds of Eu3+ disperse better and diminished the effect of concentration quenching. UV-Vis spectra and n&k analysis showed that the hybrid thin films had good transparency in visible light. Besides, the refractive index of hybrid thin films could be effectively controlled through the different ratio of SiO2 to EuL3 x 2H2O. TGA and DSC analysis indicated that the temperature of pyrolysis and T(g) increased with the increase in the SiO2 content. The results of SEM, SCMS, and AFM also showed that the hybrid thin films which prepared from the poly-functional acrylate had a flatter surface than those obtained from the single functional acrylate.

15.
J Nanosci Nanotechnol ; 9(7): 4135-42, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19916420

RESUMO

In this study, two types of the polyimide-silica hybrid thin films, 6FDA-ODA/SiO2 (FS0-FS50) and PMDA-ODA/SiO2 (PS0-PS40), with different silica content were synthesized by using the sol-gel method. TGA analysis showed that the thermal decomposition temperatures (T(d)) of FS and PS hybrid films were in the range of 457-505 degrees C and 458-516 degrees C, respectively. The T(d) increased with increasing the silica content. The measurement of contact angle and FTIR indicated that the hydrophilic and hydrolytic abilities were significantly improved when the silica content increased. The contact angle of PS0-PS40 films was in the range of 80.3-51.8 degrees. UV-Vis spectra showed that the cutoff wavelength of prepared hybrid films could be tunable through the silica content. The n&k analysis showed that the refractive index (n) of FS and PS hybrid films were in the range of 1.60-1.49 and 1.76-1.59, respectively, which could be controlled by the silica content. The extinction coefficients (k) are almost zero in the wavelength range of 300-900 nm, indicating the prepared hybrid films have an excellent optical transparency in the UV and visible region. TEM images showed that the particle size of silica in the hybrid thin films could be effectively controlled under sufficient content of coupling agent. Moreover, the results of SEM and AFM showed that the ratios of average roughness to thickness for all the prepared hybrid films were under 1.6%. It demonstrated that the prepared polyimide-silica hybrid thin films have an excellent film formability and planarity.

16.
J Nanosci Nanotechnol ; 8(3): 1537-44, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18468187

RESUMO

Nanoporous poly(methyl silsesquioxane) (PMSSQ) film was prepared through the templating of an amphiphilic block copolymer, poly(styrene-4-vinyl pyridine) (PS-b-P4VP). The experimental and theoretical studies suggest that the intermolecular hydrogen bonding is existed between the PMSSQ precursor and PS-b-P4VP. The miscible hybrid and the narrow thermal decomposition of the PS-b-P4VP lead to nanopores in the prepared films from the results of TGA, AFM, and TEM. The effects of the loading ratio on the morphology and properties of the prepared nanoporous PMSSQ films were investigated. The TEM and AFM studies show that the uniform pore morphology with pore size 10-15 nm can be prepared from a modest porogen loading level for the optimum intermolecular hydrogen bonding. The refractive index and dielectric constant of the prepared nanoporous films decreases with an increase in PS-b-P4VP loading. On the other hand, the porosity increases with an increasing PS-b-P4VP loading. This study demonstrates a methodology to control pore morphology and properties of the nanoporous PMSSQ films through the templating of PS-b-P4VP.

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