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To explore the influence of fluoro substitution position and number on optical, electrochemical and photovoltaic properties, three novel donor-acceptor (D-A) alternative copolymers (PHF, PFH and PFF) were synthesized by Stille polycondensation of 2,3-diphenyl-5,8-di(thiophen-2-yl)quinoxaline (DTQx) acceptor unit and indacenodithiophene (IDT) donor unit. As films, PHF and PFF comprising two fluoro substituents on the lateral phenyl groups displayed a broad absorption ranging from 350 to 700 nm; whereas PFH containing two fluorine atoms on the polymer main chain exhibited a slightly narrower absorption ranging from 350 to 650 nm. In addition, fluoro substitution on the polymer main chain can lower the HOMO level of the resulted polymers. As expected, PFH and PFF possess deeper HOMO energy level than PHF. Polymer solar cells (PSCs) were fabricated with these three polymers as donor materials and PC71BM as acceptor material. PHF based PSCs gave a power conversion efficiency (PCE) of 7.2% with a Voc of 0.84 V, a Jsc of 12.46 mA/cm2 and an FF of 0.69. And PFH based PSCs showed a PCE of 6.19% with a Voc of 0.93 V, a Jsc of 9.57 mA/cm2 and an FF 0.70. However, a PCE of only 2.9% with a Voc of 0.92 V, a Jsc of 4.61 mA/cm2 and an FF of 0.68 was obtained for PFF based PSCs. Transmission electron microscopy (TEM) and resonant soft X-ray scattering (R-SoXS) studies indicated that the introduction of four fluorine atoms at each repeating unit can spoil the morphology of active layer. These results highlight the importance of fluorination position and number to the performance of PSCs.

The use of environmentally friendly halogen-free organic solvents for the fabrication of polymer solar cells will be of great importance for future practical applications. In this work, a new alternative conjugated polymer with 3,4-bis(octyloxy)-phenyl substituted benzo[1,2-b:4,5-b]dithiophene as the donor unit and benzo[c][1,2,5]thiadiazole as the acceptor unit was synthesized and used as the donor material for polymer solar cells. This polymer showed good solubility in halogen-free solvents such as toluene, o-xylene and so on. The blend film morphology, charge mobility and photovoltaic performance were investigated in halogen-free solvents. The photovoltaic devices fabricated from o-xylene with N-methyl-2-pyrrolidone as additive provided the best power conversion efficiency of 4.57%, comparable to that fabricated from halogenated solvents such as 1,2-dichlorobenzene/1,8-diiodooctane with a power conversion efficiency of 4.33%. Our results demonstrate that halogen-free solvents are promising for the fabrication of high efficiency polymer solar cells.

Two novel polymers PTFBDT-BZS and PTFBDT-BZO with 4-alkyl-3,5-difluorophenyl substituted benzodithiophene as the donor unit, benzothiadiazole or benzooxadiazole as the acceptor unit, and thiophene as the spacer have been synthesized and used as donor materials for polymer solar cells (PSCs). These two polymers exhibited wide optical band gaps of about 1.8 eV. PSCs with the blend of PTFBDT-BZS:PC71BM (1:2, by weight) as the active layer fabricated without using any processing additive and any postannealing treatment showed power conversion efficiency (PCE) of 8.24% with an open circuit voltage (Voc) of 0.89 V, a short circuit current (Jsc) of 12.67 mA/cm(2), and a fill factor (FF) of 0.73 under AM 1.5G illumination, indicating that PTFBDT-BZS is a very promising donor polymer for PSCs. The blend of PTFBDT-BZO:PC71BM showed a lower PCE of 5.67% with a Voc of 0.96 V, a Jsc of 9.24 mA/cm(2), and an FF of 0.64. One reason for the lower PCE is probably due to that PTFBDT-BZO has a smaller LUMO offset with PC71BM, which cannot provide enough driving force for charge separation. And another reason is probably due to that PTFBDT-BZO has a lower hole mobility in comparison with PTFBDT-BZS.

A new low band gap polymer P1 with fluorinated acenaphtho[1,2-b]quinoxaline (AQ) as the acceptor unit and benzo[1,2-b:4,5-b′]dithiophene as the donor unit has been designed and synthesized. Comparing with its non-fluorinated analog polymer P2, P1 shows a lower band gap of 1.76 eV with a deeper HOMO energy level of −5.54 eV. Polymer solar cells with the blend of P1 and PC71BM as the active layer without the additive or annealing showed a PCE of 4.72%, which was higher than P2 based devices with a PCE of 1.65%. Obviously, P1 can endow devices with a Voc of 0.77 V and a Jsc of 10.75 mA cm−2, which are higher than that of P2 based devices with a Voc of 0.75 V and a Jsc of 4.41 mA cm−2, such an enhanced photovoltaic performance can be attributed to the broader absorption, the improvement of film morphology, and the higher charge mobility. Thus, fluorinated AQ can be a useful acceptor unit to construct narrow band gap conjugated polymers. To the best of our knowledge, this is the highest PCE report for AQ based polymer solar cells.

Two conjugated polymers with benzodithiophene derivatives as the donor unit and planar difluoro-substituted dibenzo[a,c]phenazine as the acceptor unit P1, P2-L and P2-H were designed, synthesized, and used as the donor material in polymer solar cells. P2-H exhibits the highest hole mobility of 1.54 × 10−2 cm2 V−1 s−1. Polymer solar cells (PSCs) with a blend of P1:PC71BM (1 : 1.5, by weight) as the active layer show the highest power conversion efficiency (PCE) of 6.0% with an open circuit voltage (Voc) of 0.74 V, a short circuit current (Jsc) of 12.50 mA cm−2, and a fill factor (FF) of 0.65.

Three donor–acceptor (D–A) alternating conjugated polymers with silafluorene as the donor unit, 5-alkyloxy-6-fluorobenzothiadiazole as the acceptor unit, and thiophene as the spacer has been synthesized and used as donor materials for polymer solar cells (PSCs). The introduction of a fluorine atom on the benzothiadiazole unit can lower the HOMO and LUMO energy level of the resulted polymers to afford higher open circuit voltage (Voc); whereas the introduction of a flexible alkyloxy chain on benzothiadiazole unit can increase the solubility of the resulted polymers without interfering the close packing of polymer chains in the solid state. High molecular weight polymers P-1a, P-1b, and P-1c, which are fully soluble in 1,2-dichorobenzene (DCB) at elevated temperature, have been prepared by Suzuki polycondensation. Among these polymers, P-1c exhibited the highest hole mobility up to 1.36 × 10–2 cm2 V–1 s–1. PSCs based P-1b:PC71BM demonstrated the highest Voc up to 0.98 V. P-1a:PC71BM based PSCs gave the high...

Four novel conjugated polymers (P1-4) with 9,10-disubstituted phenanthrene (PhA) as the donor unit and 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit are synthesized and characterized. These polymers are of medium bandgaps (2.0 eV), low-lying HOMO energy levels (below -5.3 eV), and high hole mobilities (in the range of 3.6 × 10(-3) to 0.02 cm(2) V(-1) s(-1) ). Bulk heterojunction (BHJ) polymer solar cells (PSCs) with P1-4:PC71 BM blends as the active layer and an alcohol-soluble fullerene derivative (FN-C60) as the interfacial layer between the active layer and cathode give the best power conversion efficiency (PCE) of 4.24%, indicating that 9,10-disubstituted PhA are potential donor materials for high-efficiency BHJ PSCs.

Three novel isoindigo based donor–acceptor (D–A) conjugated polymers P1–3 have been synthesized by Suzuki polycondensation and utilized as donor materials for polymer solar cells (PSCs). These three polymers are of the same backbone, but have different substituents. All these polymers exhibit high thermal stability and broad absorption in the range of 300 to 770 nm. Hole mobilities of polymer films spin coated from 1,2-dichlorobenzene (DCB) solutions are 7.00 × 10−4, 2.37 × 10−3 and 2.90 × 10−4 cm2 V−1 s−1 for P1, P2 and P3, respectively. PSCs based on P2:PC71BM (1 : 2 by weight) with a 2% DIO additive displayed a power conversion efficiency (PCE) of 3.41% with a short-circuit current density (Jsc) of 7.57 mA cm−2, an open-circuit voltage (Voc) of 0.85 V, and a fill factor (FF) of 53%, under the illumination of AM 1.5G (100 mW cm−2). XRD diffraction measurements have shown that these polymers have a short π–π stacking distance in the solid state. The results demonstrate that these conjugated polymers could be promising donor materials in the application of polymer solar cells.

Alcohol soluble fullerene derivative (FN-C60) has been synthesized and used as a cathode interfacial layer for high-efficiency polymer solar cells (PSCs). To examine the function of the FN-C60 interfacial layer, polymer solar cells were fabricated with blends of P3:PC71BM, HXS-1:PC71BM, PDFCDTBT:PC71BM, and PDPQTBT:PC71BM as the active layer. In comparison to the bare Al electrode, power conversion efficiencies (PCEs) of P3:PC71BM, HXS-1:PC71BM, PDFCDTBT:PC71BM, and PDPQTBT:PC71BM based PSCs were increased from 3.50 to 4.64%, 4.69 to 5.25%, 2.70 to 4.60%, and 1.52 to 2.29%, respectively, when FN-C60/Al was used as the electrode. Moreover, the overall photovoltaic performances of PSCs with the FN-C60/Al electrode were better than those of cells with LiF/Al electrode, indicating that FN-C60 is a potential interfacial layer material to replace LiF.

The synthesis, characterization, and photophysical and photovoltaic properties of two anthracene-containing wide-band-gap donor and acceptor (D-A) alternating conjugated polymers (P1 and P2) are described. These two polymers absorb in the range of 300-600 nm with a band gap of about 2.12 eV. Polymer solar cells with P1:PC71 BM as the active layer demonstrate a power conversion efficiency (PCE) of 2.23% with a high Voc of 0.96 V, a Jsc of 4.4 mA cm(-2) , and a comparable fill factor (FF) of 0.53 under simulated solar illumination of AM 1.5 G (100 mW cm(-2) ). In addition, P2:PC71 BM blend-based solar cells exhibit a PCE of 1.42% with a comparable Voc of 0.89 V, a Jsc of 3.0 mA cm(-2) , and an FF of 0.53.

6,7-Dialkoxy-2,3-diphenylquinoxaline based narrow band gap conjugated polymers, poly[2,7-(9-octyl-9H-carbazole)-alt-5,5-(5,8-di-2-thinenyl-(6,7-dialkoxy-2,3-diphenylquinoxaline))] (PCDTQ) and poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(5,8-di-2-thinenyl-(6,7-dialkoxy-2,3-diphenylquinoxaline))] (PFDTQ), have been synthesized by Suzuki polycondensation. Their optical, electrochemical, transport and photovoltaic properties have been investigated in detail. Hole mobilities of PCDTQ and PFDTQ films spin coated from 1,2-dichlorobenzene (DCB) solutions are 1.0 × 10−4 and 4.1 × 10−4 cm2V−1 s−1, respectively. Polymer solar cells were fabricated with the as-synthesized polymers as the donor and PC61BM and PC71BM as the acceptor. Devices based on PCDTQ:PC71BM (1:3) and PFDTQ:PC71BM (1:3) fabricated from DCB solutions demonstrated a power conversion efficiency (PCE) of 2.5% with a Voc of 0.95 V and a PCE of 2.5% with a Voc of 0.98 V, respectively, indicating they are promising donor materials.

Four small molecular acceptors (SM1-4) comprising a central benzene core, two thiophene bridges and two 1,8-naphthalimide (NI) terminal groups were designed and synthesized by direct C-H activation. SM1 has a planar chemical structure and forms H-aggregation as films. By attachment of different substituents on the central benzene ring, the dihedral angles between the two NI end groups of SM1-4 gradually increased, leading to a gradual decrease of planarity. SM1-4 all possess a high-lying LUMO level, matching with wide band gap (WBG) polymer donors which usually have a high-lying LUMO level. When used in OSCs, devices based on SM1 and WBG donor PCDTBT-C12 gave higher electron mobility, superior film morphology and better photovoltaic performance. After optimization, a PCE of 2.78% with a V(oc) of 1.04 V was achieved for SM1 based devices, which is among the highest PCEs with a V(oc) higher than 1 V. Our results have demonstrated that NI based planar small molecules are potential acceptors for WBG polymer based OSCs.

Four ethynylene-containing donor-acceptor alternating conjugated polymers P1–P4 with 2,5-bis(dodecyloxy) substituted phenylene or carbazole as the donor unit and benzothiadiazole (BTZ) as the acceptor unit were synthesized and used as donor polymers in bulk heterojunction polymer solar cells. The optical, electrochemical, and photovoltaic properties of these four polymers with the ethylene unit located at different positions of the polymer chains were systematically investigated. Our results demonstrated that absorption spectra and the HOMO and LUMO energy levels of polymers could be tuned by varying the position of the ethynylene unit in the polymer chains. Photovoltaic devices based on polymer/PC71BM blend films spin coated from chloroform and dichlorobenzene solutions were investigated. For all four polymers, open circuit voltages (Voc) higher than 0.8 V were obtained. P4, with ethynylene unit between BTZ and thiophene, shows the best performance among these four polymers, with a Voc of 0.94 V, a Jsc of 4.2 mA/cm2, an FF of 0.40, and a PCE of 1.6%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Three D–A alternating copolymers P1–3 with 3,7-linked 2,8-bis(alkoxy)dibenzothiophene as the donor unit and benzothiadiazole (P1 and P2) or 3,4-bis(octyloxy)benzothiadiazole (P3) as the acceptor unit have been designed and synthesized. P1–3 show two broad absorption peaks in the visible region, and the internal charge transfer (ICT) absorptions at about 530 nm in solutions and 560 nm in films of P3 are much stronger than that of P1 and P2. All the polymers show narrow band gaps below 2.0 eV and the low-lying HOMO energy levels of approximately −5.30 eV. The hole mobilities of polymer films spin-cast from 1,2-dichlorobenzene (DCB) solutions are 3.0 × 10–4, 2.7 × 10–4, and 2.3 × 10–3 cm2 V–1 s–1 for P1, P2, and P3, respectively. Under simulated solar illumination of AM 1.5G (100 mW/cm2), a PCE of 4.48% with a Voc of 0.83 V, a Jsc of 9.30 mA/cm2, and an FF of 0.58 has been achieved for PSCs with the P3:PC71BM blend (1:3, by weight) as the active layer in simply processed devices, whereas after the optimizati...

A new alternating copolymer (PSFDTBT) based on spirobifluorene, thiophene, and benzothiadiazole units has been synthesized. PSFDTBT has an optical band gap of 1.97 eV with the low-lying HOMO energy level at −5.4 eV. The hole mobility of the pristine PSFDTBT film spin-cast from o-dichlorobenzene (DCB) solution is 7.26 × 10–3 cm2 V–1 s–1 with on/off ratios in the order of 105. Polymer solar cell devices based on the blend films of PSFDTBT and PC71BM show a high open-circuit voltage of 0.94 V and a power conversion efficiency of 4.6% without any post-treatment. All the device measurements were performed in air without encapsulation. This is the first report on spirobifluorene-based conjugated polymers used for polymer solar cells, demonstrating the great potential of spirobifluorene moiety as an electron-donating unit for the construction of main chain donor–acceptor alternating conjugated polymers for high performance polymer solar cells.

A series of donor-acceptor (D-A) alternating copolymers (P1, P2 and P3) with thiophene -benzothiadiazole-thiophene-triphenylamine main chain have been synthesized by Suzuki poly-condensation. P1, P ...

A novel donor-acceptor copolymer containing 9-alkylidene-9H-fluorene unit in the main chain, poly[9-(1-hexylheptylidene)-2,7-fluorene-alt-5, 5-(4,7-di-2-thienyl-5,6-dialkoxy-2,1,3-benzothiadiazole) ...

Silole-containing conjugated polymers (P1 and P2) carrying methyl and octyl substituents, respectively, on the silicon atom were synthesized by Suzuki polycondensation. They show strong absorption in the region of 300–700 nm with a band gap of about 1.9 eV. The two silole-containing conjugated polymers were used to fabricate polymer solar cells by blending with PC61BM and PC71BM as the active layer. The best performance of photovoltaic devices based on P1/PC71BM active layer exhibited power conversion efficiency (PCE) of 2.72%, whereas that of the photovoltaic cells fabricated with P2/PC71BM exhibited PCE of 5.08%. 1,8-Diiodooctane was used as an additive to adjust the morphology of the active layer during the device optimization. PCE of devices based on P2/PC71BM was further improved to 6.05% when a TiOx layer was used as a hole-blocking layer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

In this feature article, we present a short review on the recent development in the construction of structurally perfect red and blue light-emitting materials and highlight such research in our group. We focus mainly on the three-dimensional conjugated structures such as dendrimers, hyperbranched polymers, star polymers, spirobifluorene-based polymers, and spiro-bridged ladder-type oligomers and polymers. Results indicated three-dimensional conjugated structures can efficiently decrease the aggregation of materials, resulting in the improving of the light-emitting efficiency.

A series of main chain donor-acceptor low-bandgap conjugated polymers were designed, synthesized, and used for the fabrication of polymer solar cells. The absorption spectra of low-bandgap conjugated polymers were tuned by the ratio of three copolymerization monomers. The polymers in films exhibited broad absorption ranging from 300 to 1000 nm with optical bandgaps of around 1.40 eV. All of the polymers have been investigated as an electron donor in photovoltaic cells blending with PCBM ([6, 6]-phenyl C61-butyric acid methyl ester) as an electron acceptor and power conversion efficiencies (PCEs) of 1.32–1.8% have been obtained. As for P1, PCE increases from 1.67 to 2.44% after adding 1,8-diiodooctance as an additive. The higher PCEs are probably because of better phase separation of blend films. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2571–2578, 2010

A series of polythiophene derivatives P1-P5 containing carbazole side chains were designed and synthesized via the Stille polymerization. All carbazole containing polymers showed broad absorption in the visible region. The power conversion efficiencies of solar cells based on blends of two component copolymers and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) were determinedto be0.29 and0.56% for P1and P5,respectively. For solarcells fabricated with the three component copolymers and PC61BM, the efficiencies were 0.56% for P2, 0.86% for P3, and 0.70% for P4. The introduction of electrondonating carbazole side chains can broaden the absorption in the visible region and meanwhile reduce phase separation due to the steric hinderance of the carbazole moiety to the conjugated main chain. Improving efficiency needs a balance of broad absorption and ordered packing of polymer chains in the solid state.

Polyacetylenes, poly(p-phenyleneethynylenes), and polydiacetylenes, as conjugated polymers derived from triple-bond containing building blocks, attain considerable attention because of their electronic and photoconduction properties. In this review, recent studies on the design and synthesis of conjugated polymers derived from triple-bond building blocks are summarized with an emphasis on the developments in our group in recent years. Our intense attention is focused on constructing different molecular systems with enhanced light-harvesting efficiency, and determining the functional properties of conjugated organic polymers. The conjugated organic polymers that appear in this review are useful candidates for various potential applications because of their extraordinary optical and electronic properties. The potential applications of the conjugated polymer-containing systems are explored.

An amphiphilic ethynyl-pyrene derivative modified with phosphonic acid groups (PyTOH) was synthesized and characterized. Single-stranded DNA (ssDNA), which carries negative charges, was found to induce the self-assembly of PyTOH through electrostatic interactions with Mg2+ as co-complexation ion in aqueous solution. UV–vis, fluorescence, and circular dichroism (CD) spectra revealed that left-handed helical architecture of PyTOH/Mg2+/DNA was formed. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that nanoscale structures could be fabricated by self-assembly.

A new poly(p-phenylene ethynylene) derivative with pendant 2,2′-bipyridyl groups and glycol units (PPE-bipy) has been prepared, and its metal ion sensing properties were investigated. The polymer of PPE-bipy exhibited high selectivity for Hg2+ as compared with Li+, Na+, K+, Ba2+, Ca2+, Mg2+, Al3+, Mn2+, Ag+, Zn2+, Pb2+, Ni2+, Cd2+, Cu2+, Co,2+ and Fe3+ in THF/EtOH (1:1, v/v) solution. The fluorescence of PPE-bipy was efficiently quenched by Hg2+ ions, and the detection limit was found to be 8.0 nM in a THF/EtOH (1:1, v/v) solvent system. PPE-bipy also showed a selective chromogenic behavior toward Hg2+ ions by changing the color of the solution from slight yellow to colorless, which can be detected with the naked eye. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1998–2007, 2008

A [2]rotaxane-based molecular shuttle comprised a macrocycle mechanically interlocked to a chemical "dumbbell" has been prepared in high yields by a thermodynamically controlled, template-induced clipping procedure. This molecular shuttle has two different recognition sites, namely, -NH2 +- and amide, separated by a phenyl unit. The macrocycle exhibits high selectivity for the -NH2+- recognition sites in the protonated form through noncovalent interactions, which include 1) N+-H...O hydrogen bonds; 2) C-H...O interactions between the CH2NH2+CH2 protons on the thread and the oligo(ethylene glycol) unit in the macrocycle; 3) pi...pi stacking interaction between macrocycle and aromatic unit. Upon deprotonation of the [2]rotaxane the macrocycle glides to the amide recognition site due to the hydrogen bonds between the -CONH- group and the oligo(ethylene glycol) unit in the macrocycle. The deprotonation process requires about 10 equivalents of base (iPr2NEt) in polar acetone, while the amount of base is only 1.2 equivalents in apolar tetrachloroethane. Upon addition of Li+, the conformation of the [2]rotaxane was altered as a result of the collective interactions of 1) hydrogen bonds between pyridine nitrogen and amide hydrogen atoms; 2) coordination between the oligo(ethylene glycol) unit, amide oxygen atom and Li+ cation. Then, when Zn2+ ions are added, the macrocycle returns to the deprotonated -NH- recognition site owing to coordination of the macrocycle and -NH- from the axle with the Zn2+ ion. All the above-mentioned movement processes are reversible through the alternate addition of TFA/iPr2NEt, Li/[12]-crown-4 and Zn2+/ethylenediaminetetraacetate (EDTA), by virtue of hydrogen bonding and metal-ion complexation. Significantly, the three independent movement processes are all accompanied by fluorescent responses: 1) complete repression in the protonated form; 2) low-level expression in the deprotonated form; 3) medium-level expression following addition of Li+; 4) high-level expression on complexation with Zn2+.

A simple and effective strategy for synthesis of bis-dipolar trimeric OPVs (a–g) with same push–pull electron groups at the two ends is presented. Their photophysical and electrochemical properties were investigated by UV–vis, fluorescence spectroscopies, and voltammetry techniques. A successful tuning in the emission color was achieved and the LUMO energy level was found to correlate with the Hammett constant of the respective substituents, providing a powerful strategy for prediction of the photoelectrical properties of the new chromophores.

A new amphiphilic polymer containing pyridine units was synthesized and characterized. The solvent-dependent conformational transition from extended transoid to helical cisoid was studied by absorption, fluorescence, and 1H NMR measurements. The polar solvent promoted the formation of the helical structures. A metal ion or H+ could stabilize the ordered structure. Moreover, the solvophobically induced helical structure was stable to environmental stimuli. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1403–1412, 2007.

A series of oligo(phenylenevinylene)s (OPVs) of different lengths containing aldehyde and dialdehyde groups on the ends were synthesized and characterized. Their photophysical properties were also investigated via ultraviolet–visible, steady-state, and time-resolved fluorescence spectra. The results indicated that the absorption maximum, radiative rate constant, and excitation maximum of an OPVnCHO oligomer series (where n represents the oligomeric length) showed linear relationships with the reciprocal number of conjugated units. Similarly, the absorption maximum and emission lifetime of the oligomers of an OPVn–2CHO series showed linear relationships with the reciprocal number of conjugated units. The dependence of the fluorescence intensities of the OPVs on the concentration of the quencher C60 was evaluated. Apparently, upon photoexcitation, the OPVs underwent significant fluorescence quenching. The results for different OPV derivatives and a quenching mechanistic discussion showed that the static quenching contribution was indeed responsible for the significant upward curvature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 911–924, 2007

Performance enhancement of polymer solar cells (PSCs) is achieved by expanding the absorption of the active layer of devices. To better match the spectrum of solar radiation, two polymers with different band gaps are used as the donor material to fabricate ternary polymer cells. Ternary blend PSCs exhibit an enhanced short-circuit current density and open-circuit voltage in comparison with the corresponding HD-PDFC-DTBT (HD)- and DT-PDPPTPT (DPP)-based binary polymer solar cells, respectively. Ternary PSCs show a power conversion efficiency (PCE) of 6.71%, surpassing the corresponding binary PSCs. This work demonstrates that the fabrication of ternary PSCs by using two polymers with complementary absorption is an effective way to improve the device performance.

Novel dibenzocoronenetetracarboxylic acid diimide analogues and naphthoperylenetetracarboxylic acid diimide analogues containing imidazole, 1,2,4-triazole, and pyrazole rings embedded as functional constituents within the parent hydrocarbon backbone have been synthesized. The pi-rich and pi-poor heterocycles have different influences on the physical properties of the parent benzocoronenetetracarboxylic acid diimide and naphthoperylenetetracarboxylic acid diimide systems. The pi-rich 3 was able to self-assemble into one-dimensional nanostructures through strong pi-pi stacking, whereas the pi-poor 8 lacked the one-dimensional self-assembly capability, thus offering the potential to control the self-assembly capability of the pi-conjugated perylene core by decoration with N-heterocycles.

A series of new polymers containing porphyrin, poly(p-phenylenevinylene) (PPV), and/or a pendant fullerene unit has been synthesized. The cyclic voltammetry showed us a good candidate for a photoinduced electron-transfer system. More important, the photocurrent measurement revealed an interesting phenomenon that the photocurrent increased with the contents of the fullerene in the polymers increased. SEM images displayed the aggregation superstructures of three polymers. Nanobriquetting, nanofiber, and hierarchical porous structure were observed, respectively. The results indicated that the axial coordination of metal porphyrin and Bipy was very important to control the aggregation morphologies of the polymers.

High-molecular-weight conjugated polymer HD-PDFC-DTBT with N-(2-hexyldecyl)-3,6-difluorocarbazole as the donor unit, 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit, and thiophene as the spacer is synthesized by Suzuki polycondensation. HD-PDFC-DTBT shows a large bandgap of 1.96 eV and a high hole mobility of 0.16 cm(2) V(-1) s(-1) . HD-PDFC-DTBT:PC71 BM-based inverted polymer solar cells (PSCs) give a power conversion efficiency (PCE) of 7.39% with a Voc of 0.93 V, a Jsc of 14.11 mA cm(-2) , and an FF of 0.56.

Shape-persistent macrocycles have attracted considerable interest as molecular components in the fields of supramolecular chemistry and materials science due to their unique molecular structures and properties. These rigid molecular rings with a nanoscale sized hole in the center may be tailored with specific chemical constitutions, geometrical shapes, peripheral functional groups, and so on. Recent advances in the preparation, supramolecular self-assembling, and practical applications of shape-persistent macrocycles have verified this class of molecules as promising building blocks for supramolecular chemistry and nanodevice fabrication. Intense efforts have been devoted to the synthesis of shape-persistent macrocycles, and they have been well summarized in several excellent reviews. The most successful methods used in the synthesis of shape-persistent macrocycles include the following approaches: 1) intramolecular ring closure of a,w-difunctionalized oligomer strategy and the one-pot intermolecular coupling and intramolecular cyclization method; 2) the template strategy; 3) thermodynamically controlled synthetic strategies. Based on these elegant synthetic strategies, a large number of shape-persistent macrocycles with well-defined shapes and sizes have been prepared and reported. Recently, Sherburn and Sinclair found that Suzuki– Miyaura coupling of diiodoaryls and arylboronic acid in a feed ratio of 10:1 afforded the product of double coupling in good yields. Hu and Dong demonstrated that the use of [Pd2ACHTUNGTRENNUNG(dba)3] and tBu3P as the catalyst precursor for Suzuki– Miyaura cross-coupling of dibromobenzenes with arylboronic acid (1 equiv) afforded exclusively diaryl-substituted benzenes. Scherf et al. reported the cross-coupling of 2,7-dibromofluorene with arylboronic acid (1 equiv) formed preferentially the diaryl-substituted fluorenes. Yokozawa et al. reported chain-growth Suzuki–Miyaura polymerization of an AB-type monomer, bromoarylboronic acid, using [PdBr{P ACHTUNGTRENNUNG(tBu)3}(Ph)] as an arylpalladium halide catalyst. Kiriy et al. have successfully grafted polyfluorene onto a functionalized surface by catalyst-transfer chain-growth Suzuki–Miyaura polycondensation of 7-bromo-9,9-bis(2ethyl-hexyl)-9H-fluoren-2-ylboric using [Pd ACHTUNGTRENNUNG(tBu3P)2] as the catalyst precursor. Very recently, Yokozawa et al. have demonstrated that catalyst-transfer Suzuki–Miyaura polycondensation can be used to prepare even diblock conjugated polymers with a narrow molecular weight distribution. We have recently demonstrated that the catalyst-transfer Suzuki–Miyaura cross-coupling (CTSMCC) reaction can be used to prepare hyperbranched polymers with a branching degree of 100%. We think the unique catalyst-transfer behavior can be used to prepare shape-persistent macrocycles. Herein, we report the application of the CTSMCC reaction in the preparation of shape-persistent macrocycles. To the best of our knowledge, this is the first example of the synthesis of macrocycles by the CTSMCC reaction. Four macrocycles were selected as targeted macrocycles to verify our idea. Due to the competition of linear polymerization, a onepot reaction usually affords macrocycles in very low yield. Therefore, the synthesis of shape-persistent macrocycles normally requires pseudo high dilution. The reactants are usually added to the reaction vessel by a syringe pump over [a] W. Huang, M. Wang, C. Du, Dr. Y. Chen, L. Su, C. Zhang, Prof. Dr. Z. Bo Institute of Chemistry CAS Beijing 100190 (P.R. China) Fax: (+86)10-82618587 E-mail : zsbo@iccas.ac.cn [b] Dr. R. Qin, Prof. Dr. Z. Liu, C. Li, Prof. Dr. Z. Bo Institute of Polymer Chemistry and Physics College of Chemistry, Beijing Normal University Beijing 100875 (P.R. China) Fax: (+86)10-62206891 E-mail : zsbo@bnu.edu.cn Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201002574.

A novel carbazolyldiacetylene derivative of 5-[1,2]dithiolan-3-ylpentanoic acid 1,6-bis((N-carbazol-3-yl)methyl)-2,4-hexadiyne ester (DCHD-HS) was synthesized. DCHD-HS showed unusual fluorescence enhancement when it was bound to gold nanoparticles. The studies also showed that varied solvents and ratios of ligand/gold particles that served as the driving forces to control aggregation resulted in emission enhancement. A rational explanation for this phenomenon was discussed and elucidated.

The synthesis and sensing characteristics of a new class of colorimetric and fluorometric dual-modal probe for mercury ion are outlined. Judicious placement of two dithia-dioxa-aza macrocycles on the BODIPY chromophore generates this interesting molecule. A highly Hg2+-selective fluorescence enhancing property (>7-fold) in conjunction with a visible colorimetric change from purple to red-pink can be observed, leading to potential fabrication of both “naked-eye” and ratiometric fluorescent detection of Hg2+.

A dual-mode fluorescence switch controlled by external inputs such as protons and metal ions is described, and each state corresponds to a specific fluorescent emission peak. Based on the reversible changes of the fluorescence emission of the switch responding to different external stimuli, the corresponding integrated logic gates and communication networks have been constructed in solid film or in solution.

High molecular weight thiophene-containing conjugated polymers were successfully synthesized by Suzuki polycondensation of aryl dibromides and 2,5-thiophenebis(boronic acid) derivatives by using a new thiophene-containing bulky phosphorous compound as the ligand for a zerovalent palladium catalyst.

Three new isoindigo containing donor–acceptor (D–A) type conjugated polymers were synthesized by palladium catalyzed Suzuki polycondensation and used as donor materials for polymer solar cells (PSCs) and field effect transistors (FETs). All the polymers possess good solubility in common organic solvents, high thermal stability, and broad absorption in the range of 300 to 750 nm. These polymers have narrow band gaps (1.66 to 1.70 eV) and low lying HOMO energy levels (5.15 to 5.31 eV). Hole mobilities of these polymers are in the range of 1.78 × 10−3 to 2.62 × 10−3 cm2 V−1 s−1. PSCs based on P3:PC71BM (1 : 2, by weight) gave the best device performance with a power conversion efficiency (PCE) of 1.75%, a short-circuit current density (Jsc) of 4.74 mA cm−2, an open-circuit voltage (Voc) of 0.81 V, and a fill factor (FF) of 0.45, indicating these polymers can be promising donor polymers for polymer solar cells.

Two derivatives of tetraphenylethene (TPE) were synthesized through one step cross McMurry coupling reaction. Both luminogens exhibit aggregation-induced emission (AIE) and crystallization induced emission enhancement (CIEE). The emissions of both luminogens could be switched between blue and green through reversible modulation of morphology with thermal, organic solvent fuming and mechanical stimuli. Thus we provide a possible design strategy for emission switching materials.