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Fluorescent chemosensors based on pillararene complexes represent a new, promising branch in sensor technology. Because of CH⋅⋅⋅π interactions, aliphatic chains are well suited for the columnar cavities of pillararenes and bulky or sheet-like (sub)structures can be arranged on the portals. Thus, pillararenes form versatile receptors and an alteration of the fluorescence behavior upon complexation ensures the function of these chemosensors as the reporter. Although this field of research exists only since a few years, remarkable chemosensors were developed for substances as diverse as medical drugs, biochemicals, herbicides and explosives.

Four novel metal-free organic dyes WL1a-b and WL2a-b containing di(1-benzothieno)[3,2-b:2′,3′-d]pyrrole (DBTP) as electron donor were synthesized and applied for dye-sensitized solar cells (DSSCs), where DBTP was firstly employed as a donor in the organic dyes. It has been demonstrated that the dyes WL with DBTP as a donor show better photovoltaic performance than the reference dye PTZ with phenothiazine as a donor. In comparison with WL1a-b with one cyanoacrylic acid as mono-anchor, WL2a-b with two cyanoacrylic acids as bi-anchors show a broader light absorption on the TiO2 film and higher molar extinction coefficients in solution, resulting in higher power conversion efficiency. Under standard global AM 1.5G solar light condition, WL2a sensitized solar cell obtained a high power conversion efficiency of 8%. The results indicate that the DBTP unit can be applied as an effective electron donor and DBTP-based organic dye is a promising candidate for efficient DSSCs.

Two efficient dye-sensitized solar cells have been fabricated by two novel D–D–π–A phenothiazine-based organic dyes (PH2 and PH3) with an encapsulated insulated molecular wire (EIMW) as an auxiliary donor. The cell sensitized by PH2 with EIMW as an auxiliary donor shows a much higher photovoltage (Voc) relative to the reference dye PH1 without EIMW, because the former dye can inhibit dye aggregation and suppress the charge recombination effectively. The results show that the cell sensitized by PH2 with co-adsorption of chenodeoxycholic acid obtains a high power conversion efficiency, even higher than that of the cell based on N719. Thus, an effective way to increase the photovoltage and efficiency of the DSSCs has been developed by introducing the EIMW into the organic dyes due to the effective inhibition of dye aggregation and charge recombination.

Squaraines, two-fold condensation products in 1,3-position of squaric acid, represent dyes or pigments of high actuality. After their first boom in electrophotography diverse applications are presently studied in a wide area of research, which reaches from electrooptical materials to biosensors and compounds used in photodynamic therapy. Absorption and/or emission ranges in the NIR are mandatory for many of these techniques. The present article deals with stilbenoid squaraines, which feature an extended conjugation in their biradicaloid D-π-A-π-D structure. Due to the charge-transfer character of the excitation, boundaries are set for the optimal length of the conjugation. The absorption maxima of the stilbenoid squaraines and their aggregates are lying in chloroform as a solvent between 600 and 1000 nm. In the solid state panchromatic absorptions can be observed, which reach far into the NIR region. The facile preparation of squaraines bearing stilbene building blocks in one or two of their arms and moreover the easy access to dyes with multiple squaraine units fixed to stilbenoid scaffolds promise a wide palette of further applications in materials science.

In this paper, the encapsulated insulated molecular wire (EIMW) and 2′,7′-bis(hexyloxy)spiro[cyclopenta[2,1-b:3,4-b′]dithiophene-4,9′-fluorene] (SPDF) were specifically designed as efficient anti-aggregation π-bridges for two novel D–A–π–A metal-free sensitizers (IBT1 and IBT2). Compared with the reference dye IBT3 with 3,3′-dihexyl-2,2′-bithiophene (DHBT) as an anti-aggregation π-bridge, both the dyes IBT1 with EIMW and IBT2 with SPDF as π-bridges can suppress intermolecular aggregation more efficiently. The π-bridge of SPDF shows the strongest anti-aggregation ability due to the rigid ‘T’ configuration among these dyes. Meanwhile, the π-bridge of EIMW shows better anti-aggregation ability than DHBT because of the larger steric hindrance of the former. Finally, when the dyes IBT1 and IBT2 are co-sensitized with IBT3, respectively, the new devices exhibit high efficiencies of 7.85% and 7.64%, respectively, which are comparable to that of N719 (7.85%). The results demonstrate that the dyes with EIMW and SPDF as anti-aggregation π-bridges are promising candidates for efficient DSSCs and dye aggregation can be effectively inhibited by structural engineering of the π-spacer.

Three novel diketopyrrolopyrrole (DPP) based small organic molecules were synthesized as hole transporting materials for perovskite solar cells. The effects of different donors and π bridges on the performance of perovskite solar cells (PSCs) were discussed. The efficiency of TPADPP-1, TPADPP-2, PTZDPP-2 was 5.10%, 9.85% and 8.16% respectively. Compared to TPADPP-2, the voltage of PTZDPP-2 was higher. Because the electron-donating ability of phenothiazine based donor was larger than that of triphenylamine based donor, the HOMO level of PTZDPP-2 was lower than that of TPADPP-2. The results indicated that the diketopyrrolopyrrole based D-π-A-π-D type small organic molecule might be a promising hole transporting material in the perovskite solar cells.

Using fluorometry to study the interactions between guests and host cavities is often challenging, especially for hosts with small cavities because the fluorophore may not be close to the binding site. Therefore, it is critical to overcome this hurdle to broaden the applicability of fluorometry in supramolecular chemistry. Herein, we designed a fluorescent-cavity host (H1) by conjugating the binding site of a pillar[5]arene cavity and studied its host-guest recognition mechanism in the cavity. Distinct fluorescent responses of H1 were observed for cyano homologues: the fluorescence was enhanced for succinonitrile but quenched for malononitrile. Such an unusual phenomenon with such subtle difference in guest structure was attributed to the different host-guest interactions induced by the subtle difference of guest locations within the H1 cavity. Our results indicate that developing fluorescent-cavity hosts as probes will provide a powerful and insightful way to explore the exquisite detail of host-guest recognition, self-assembly, and molecular machinery.

Three novel quinoxaline-based donor-π-acceptor type organic dyes were synthesized and explored as sensitizers in dye-sensitized solar cells (DSSCs). The impacts of various π-conjugation configurations which contain different quinoxaline derivatives on the absorption properties, electrochemical properties and photovoltaic performances, as well as theoretical calculations have been investigated systematically. The photovoltaic performances of these dyes were found to be highly relevant to the π-conjugated configurations. In particular, the DSSC based on the dye with 2,3-dioctylquinoxaline as the spacer exhibited the highest efficiency of 8.20% with a short-circuit photocurrent density of 17.83 mA cm−2, an open-circuit photovoltage of 0.71 V, and a fill factor of 0.65, under standard global AM 1.5G solar light condition. However, the DSSC based on the dye with a more conjugated dithieno [2,3-a:3′,2′-c]phenazine core as the spacer exhibited a lower efficiency due to serious intermolecular aggregation. When the intermolecular aggregation is inhibited, the efficiency can be improved greatly. The results confirm that the configuration of the π-conjugation of the dyes should be considered for the improvement of the photovoltaic performance.

Two novel zinc porphyrin dyes containing either benzotriazole or 2 H -[1,2,3]triazolo[4,5- c ]pyridine as auxiliary acceptors, respectively, were synthesized for dye-sensitized solar cells. These two auxiliary acceptors were firstly applied into porphyrin based dyes. The photophysical and electrochemical properties of the dyes were investigated. These two dyes show the whole visible light absorption when they are adsorbed on the TiO 2 film, which means that they are promising sensitizers for dye-sensitized solar cells. The absorption intensity of the triazolopyridine containing dye is higher than that of the benzotriazole containing dye, resulting in a better light harvesting. Thus, the dye-sensitized solar cell based on the former dye achieved higher conversion efficiency of 6.65% than the cell based on the latter dye (6.17%) with chenodeoxycholic acid as the coadsorbant.

Double branched donor acceptor compounds (D–π–A)2L, whose separate branches are linked by saturated chains or ring systems, are highly promising sensitizers for dye-sensitized solar cells (DSSCs). Their photovoltaic performance η (power conversion efficiency PCE) is higher than the η value of the corresponding single branched sensitizers D–π–A. This advantage can be attributed to the lower aggregation tendency and to the higher loading density of the chromophores on the semi-conductor surface (TiO2). Moreover, the intramolecular transfer of the excitation energy can enhance the contact time of the adsorbed dye molecules in the excited state S1 and thus reduce the unwanted charge recombination (dark current).

Summary The improvement of open-circuit voltage (VOC) is a crucial goal to develop efficient dye-sensitized solar cells (DSSCs). Here, conjugating pillar[5]arene dyes (PPI and PPII) are designed, synthesized, and applied in DSSCs. The presence of pillar[5]arene moiety in the dyes inhibits the dye aggregation and charge recombination in the DSSCs, leading to the enhancement of VOC. PPI with a single D-π-A backbone and a pillar[5]arene moiety achieves a VOC of 715 mV, which is much higher than the reference dye (VOC of 674 mV) with the same D-π-A backbone but no pillar[5]arene moiety. PPII with 2 D-π-A backbones also achieves a VOC of 746 mV and a much higher short-circuit photocurrent (JSC) than the reference dyes. In addition, the host-guest interaction can adjust the VOC and JSC by coupling dye with the imidazolium in electrolyte, as confirmed by the electrolyte engineering.

Four novel organic dyes DT1-DT4 containing a dithienopyrrolobenzotriazole unit were synthesized and applied in dye sensitized solar cells, where dithienopyrrolobenzotriazole moiety was introduced as a π-spacer for the first time. The four dyes exhibited good light harvesting efficiency with high molar extinction coefficients and broad spectral response. The influence of the different electron donor on the photovoltaic performance was evaluated. The effects of the linear and branched alkyl chains in the π-bridge on the photophysical, electrochemical and photovoltaic performance were systemically investigated. The results show that branched alkyl chains are better than linear alkyl chains in inhibition of intermolecular aggregation and electron recombination between the injection electrons and electrolyte. Finally, DT4 sensitized solar cell obtained a power conversion efficiency of 8.05%. These results indicate that the dithienopyrrolobenzotriazole-based organic sensitizer is a promising candidate for efficient dye sensitized solar cells.

Two novel organic dyes TLEP-1 and TLEP-2 based on phenothiazine with trilateral π-conjugation extensions were designed and synthesized for dye-sensitized solar cells, where phenothiazine ring was linked with two phenyl moieties at 7- and 10-positions as the first and second π-conjugation extensions, and with furan or thiophene ring at 3-position as the third π-conjugation extension for TLEP-1 and TLEP-2, respectively. The influence of the π-conjugation extensions on the photovoltaic performance was evaluated. The cell based on TLEP-2 exhibits an impressive short-circuit photocurrent density of 14.87 mA cm−2, which is much higher than the cell based on the reference dye without π-conjugation extension (9.01 mA cm−2), leading to high power conversion efficiency of 7.33% under simulated AM 1.5 G illumination condition. The results indicate that the trilateral π-conjugation extensions are an effective way to improve the photovoltaic performance of the dye-sensitized solar cells.

As an emerging photovoltaic technology, dye-sensitized solar cells (DSSCs) have attracted a great deal of academic and industrial interest due to their reasonably high power conversion efficiency, low material cost and facile fabrication process. Metal-free organic dyes, as one of the key components of DSSCs, play a pivotal role in light harvesting and electron injection. Among the various species of organic dyes, easily tunable 10H-phenothiazine-based dyes hold a large proportion. The electron-rich nitrogen and sulfur atoms render 10H-phenothiazine a stronger donor character than other amines, even better than triphenylamine, tetrahydroquinoline, carbazole and iminodibenzyl. On the other hand, the unique non-planar butterfly conformation of the 10H-phenothiazine ring can sufficiently suppress molecular aggregation and the formation of excimers. The positions N-10, C-3 and C-7 of the 10H-phenothiazine ring system can easily be furnished with electron-donating or electron-withdrawing groups. Thus, the structural features of 10H-phenothiazine-based dyes guarantee the fabrication of efficient DSSCs. Some 10H-phenothiazine-based dyes show high photovoltaic performance, even better than the commercial ruthenium complex (N719). This paper reviews the recent significant scientific progress in 10H-phenothiazine-based DSSCs and focuses especially on the relationship between the molecular structure and the photoelectric conversion properties.

A pillar[5]arene-containing cross-linked polymer was synthesized via Williamson reaction involving monohydroxy pillar[5]arene with chloromethylated polystyrene. Its adsorption behavior towards guests was investigated. It was found that the pillar[5]arene-containing polymer exhibited good adsorption capacities towards dihaloalkanes and dinitriles by host-guest complexation.

Bisphosphorylpillar[5]arenes ( and ) were synthesized and used to study the host-guest complexation in organic solvents and water. The interactions between the guests and the phosphate of the hosts lead to strong binding towards alkyl dihalides and alkyldiammonium ions. may be used to detect or separate alkyl dihalides in water due to the rapid precipitation of the complex.

A series of novel di(1-benzothieno)[3,2-b:2′,3′-d]pyrrole (DBTP)-based organic dyes (WL5-10) with D-D-π-A or D-D-A-π-A configurations are designed and the relationship between the properties and molecular configurations of these organic dyes are studied systematically. WL5,7–8 with D-D-π-A configuration incorporating triphenylamine or phenothiazine as donor and DBTP as auxiliary donor and WL9-10 with D-D-A-π-A configuration incorporating benzothiadiazole as an auxiliary acceptor are synthesized to study the effect of the molecular engineering on the photovoltaic performance. WL5,7–8 exhibit similar absorption spectra and high molar extinction coefficient. Especially, the dye WL5 with phenothiazine as terminal donor displays a high PCE of 6.75%, which is much higher than that of the dye WL1a with D-π-A configuration. WL9-10 show the weakest performance, which is attributed to electron trap and mismatch of energy-level due to the strongest electron withdrawing group benzothiadiazole. Finally, a high power conversion efficiency of 7.94% with chenodeoxycholic acid as the co-absorbent for the DSSC based on WL5 is achieved. The results indicate that the molecular engineering of the dyes affects the photovoltaic performance greatly, and the DBTP-based organic dye with D-D-π-A configuration by incorporating an extra terminal donor might be an effective approach to enhance the photovoltaic performance.

Supraspheres were prepared from a pillar[5]arene-based linear polymer (the host) and several multitopic guests. According to host-guest binding studies in nanosystems, the optical and structural properties (fluorescence capability, density, and particle size) of the nanoparticles were correlated not with the host-guest binding affinities, but with the relative fluorescence quantum yield.

Two novel metal-free organic dyes bearing two asymmetric double donor–acceptor segments were synthesized. Their physical, optical, electrochemical properties and photovoltaic performances were investigated. Compared with the mono-anchoring dye containing single donor–acceptor chain, these new dyes exhibited a broader and much stronger absorption in the light wavelength ranging from 400 to 600 nm, showed higher IPCE values and short-circuit current density, which led to more efficient photovoltaic performance. The dye with triphenylamine and phenothiazine as two electron donors and two cyanoacrylic acids as two electron acceptors exhibited an impressive power conversion efficiency of 5.92% under simulated AM 1.5 G illumination condition with an open-circuit photovoltage of 796 mV, a short-circuit photocurrent density of 11.24 mA/cm2, which is 22% higher than that of the mono-anchoring dye based counterpart. The results indicate that the asymmetric di-anchoring organic dyes are promising sensitizers for high efficient dye-sensitized solar cells.

Five novel metal-free organic dyes DQ1-5 containing a dipentyldithieno[3,2-f:2',3'-h]quinoxaline (DPQ) unit were synthesized and applied in dye-sensitized solar cells (DSSCs), where DPQ was employed as a π-spacer for the first time. Their photophysical, electrochemical, and theoretical calculations and photovoltaic properties were systematically investigated. All the five dyes show broad photoresponse. Especially the absorption edges of DQ3-5 extend to 800 nm on the TiO2 films. The inserted electron-rich unit 3,4-ethylenedioxythiophene or electron-withdrawing group benzothiadiazole (BTD) in DPQ-based dyes can greatly influence the optoelectronic properties of the dyes. In addition, the different electron donors also significantly affect the performance of the DSSCs. Under standard global AM 1.5 solar light conditions, the DQ5 sensitized solar cell obtained a power conversion efficiency of 7.12%. The result indicates that the rigid DPQ-based organic dye is a promising candidate for efficient DSSCs.

Two different synthetic concepts led to the formation of 17, 19, and 29, the first structural isomeric benzobis[1,3]oxathiins. Hetero-DielsAlder reactions of diethyl mesoxylate 14 and the open valence isomers of the benzobisthietes 12 and 18 yielded the linear benzobis[1,3]oxathiin 17 and its angular isomer 22, respectively. The isomeric angular system 29 could be obtained by a twofold O,S-acetalization reaction of the dihydroxydisulfanyl compound 27 and acetone (28).

Pillar[n]arenes are a fast-growing research topic in supramolecular chemistry. Originally the focus was predominantly on pillar[5]arenes; however, now more and more studies on pillar[6]arenes are being performed. The ability and selectivity of host–guest complexations depend strongly on the size of the inner cavities of these macrocycles. New results have stimulated us to compile the synthetic entries and the complexations of pillar[6]arenes with large cylindric cavities that offer space for many different guest molecules. 1 Introduction 2 Preparation of Pillar[6]arenes 2.1 Pillar[6]arenes by Macrocyclization Reactions 2.2 Hydroxypillar[6]arenes through Ether Cleavage 2.3 Hydroxypillar[6]arenes by Redox Reactions 2.4 Alkylation of Hydroxypillar[6]arenes 2.5 Pillar[6]arenes Obtained from Preformed Pillar[6]arenes by Transformation of Alkoxy Chains 3 Structure of Pillar[6]arenes in the Crystalline State and in Solution 3.1 Dodecaalkoxypillar[6]arenes 3.2 Perhydroxypillar[6]arenes 4 Generation of Complexes 4.1 Inclusion of Guest Molecules 4.2 Complexes of Ammonium Compounds 4.3 Complexes of Pyridinium Compounds 4.4 Complexes of Other Cations 4.5 Complexes of Electroneutral Guest Molecules 4.6 Complexes of Anions 4.7 Self-Assembly by Complexation 4.8 Binding on Metal Surfaces 4.9 Capture of Gases and Vapors 5 Conclusion

A systematic research of the structural characterization and the host-guest binding abilities between three types of pillar[5]arenes 3–5 (3 for Structure Type I, 4 for Structure Type II and 5 for Structure Type III) is carried out by 1H NMR measurements and X-ray study. The results show that the configurations or symmetry of their cavities not only have large difference in these three types of pillar[5]arenes, but also have more or less variations even in the same structure type or the same host locked different guests such as crystals of 3a–3b, 4a–4d. On the other hand, the complexation behavior of pillar[5]arenes with 1,4-dibromobutane (DBB) is affected by the different symmetrical structure or substituents on the rings.

A new di-anchoring organic dye based on phenothiazine featuring A-D-π-D-A (acceptor-donor-π-linker-donor-acceptor) configuration with fluorene as the π linker was designed and successfully synthesized. Compared to the corresponding mono-anchoring D-A congener, this new dye exhibited a broader and stronger absorption in the light wavelength ranging from 400 nm to 600 nm and thus showed a more efficient photovoltaic performance for dye-sensitized solar cells (DSSCs). The overall power conversion efficiency (η) of this new dye in a sensitized solar cell amounted to 5.70%, which is 17% higher than that of the equivalent based counterpart (4.87%). On the other hand, the introduction of two thiophene units at position-2 and -7 of the fluorene unit gave another new dye with extended conjugation. This extended conjugation dye showed a higher molar extinction coefficient (e), but exhibited π-stacked aggregation on the TiO2 surface, resulting in low efficiency of electron injection. The results indicate that the di-anchoring dye with fluorene as π linker is a promising candidate for efficient DSSCs.

Two novel double branched D–π–A organic dyes (DB dyes) are synthesized to investigate the influence of the linkage location in DB dyes on the performance of dye-sensitized solar cells (DSSCs), where phenothiazine is introduced as a donor, thiophene–benzotriazole unit as the π-bridge and cyanoacrylic acid as the electron-acceptor. The photophysical, electrochemical and photovoltaic properties of the dyes are systematically investigated. The results show that the location of the linkage unit has a small effect on the physical and electrochemical properties of the dyes. However, when the dyes are applied in DSSCs, an obvious decline of short-circuit current (Jsc) and open-circuit voltage (Voc) is found by moving the linkage unit from the donor part to the π-bridge part. The DSSC based on the dye DB-D with the linkage unit in the donor obtains an overall power conversion efficiency of 6.13%, which is about 68% higher than that (3.65%) of the DSSC based on the dye DB-B with the linkage unit in the π-bridge. The DB-B based device exhibits a lower efficiency due to its serious aggregation and short electron lifetime. The results indicate that the linkage location of the dyes has a big effect on the performance of the DSSCs.

Three types of novel diketopyrrolopyrrole-based organic dyes ( Type 1 – 3 ) with phenyl unit as an additional π -bridge and triphenylamine or phenothiazine as the donors are designed and synthesized for dye-sensitized solar cells (DSSCs). Type 1 dyes incorporating the donor segment directly to the diketopyrrolopyrrole core lead to a better electron communication between the donor and acceptor, allowing an efficient charge transfer process. Type 2 and Type 3 dyes with a phenyl unit between the donor and diketopyrrolopyrrole unit show lower delocalization of the excited state. Compared with Type 3 dyes, Type 1 dyes exhibit higher conjugated skeleton co planarity and shorter electron transfer distance from the donor to TiO 2 , resulting in the red-shifts of absorption and promotion of electron injection, respectively. Moreover, the dyes with triphenylamine as the donor display better UV performance and lower trend of aggregation than the dyes with phenothiazine as the donor. Finally, a power conversion efficiency of 8% with chenodeoxycholic acid as the co-absorbant for the DSSC based on Type 1 dyes with triphenylamine is achieved. The results reveal that the donors, the position and number of phenyl unit of the dyes significantly influence the photovoltaic performance of their DSSCs.

The solid-state structure of star-shaped 2,4,6-tris{(E)-2-[4-(dimethylamino)-phenyl]ethenyl}-1,3,5-triazine is determined from a powder sample by exploiting the respective strengths of single-crystal three-dimensional electron diffraction and powder X-ray diffraction data. The unit-cell parameters were determined from single crystal electron diffraction data. Using this information, the powder X-ray diffraction data were indexed, and the crystal structure was determined from the powder diffraction profile. The compound crystallizes in a noncentrosymmetric space group,P212121. The molecular conformation in the crystal structure was used to calculate the molecular dipole moment of 3.22 Debye, which enables the material to show nonlinear optical effects.

2,4-Bis(2,5-dipropyloxyphenyl)-6-phenylpyridine (6), obtained by a one-pot reaction of enone 3, ketone 4 and ammonium acetate (5), is characterized by its molecular structure in the crystalline state, which deviates far from planarity. The interplanar angles of the three benzene rings amount up to 46° in relation to the central pyridine ring

Three organic dyes with double D–A system were synthesized and applied in the dye-sensitized solar cells. These dyes contain phenothiazine as an electron donor and cyanoacetic acid as an acceptor/anchor. Linkages were incorporated at the ortho-, meta- and para-positions and their impact on the performance of photovoltaic was observed. Among them, the dye with a para-position linkage exhibited the highest short-circuit photocurrent density (12.26 mA cm−2) and open-circuit photovoltage (756 mV), leading to the best overall efficiency (6.14%) due to better light harvesting capacity under standard global 1.5 AM conditions. Under similar measuring conditions the dyes with ortho and meta-position linkage delivered sunlight to electricity conversion efficiencies of 5.25% and 5.85% respectively. The result shows the position isomer of the linkage units influences the photophysical characteristics, dye loading on the film and electron lifetime.

Since 2008 a new field of supramolecular chemistry has developed rapidly: the chemistry of pillar[n]arenes. These “younger brothers and sisters” of calixarenes are conveniently accessible and extremely guest-friendly. Guests from many different classes of organic compounds are welcome. Nevertheless, a high selectivity for the threading of guest molecules in the macrocyclic cavities can be achieved. The complex stability is characterized by association constants Ka between 10 and 1×108 M−1. The rate constants of the threading vary over several orders of magnitude. The focus of this article lies on the preparation (sections 2 and 3) and the structures (section 4) of pillar[n]arenes (n=5–10) in solution and in the solid state. A further important point concerns the complexation and its selectivity (section 5). Only some new or outstanding examples are discussed in section 6 on self-assembly and aggregation.

Four novel D–π–A metal-free organic dyes DTP1–4 containing a dithienopyrrolobenzothiadiazole (DTPBT) unit were synthesized and applied in dye-sensitized solar cells, where DTPBT was employed as a π-spacer for the first time. The photophysical, electrochemical and photovoltaic properties of the dyes were systematically investigated. The dyes DTP1–4 showed broad absorption spectra and high molar extinction coefficient, resulting in high light harvesting efficiency. In addition, the impacts of donors and the thiophene unit as an additional π-spacer were also studied. The results showed that the dye DTP4 with triphenylamine as the donor exhibited better photovoltaic performance than DTP1–3 with phenothiazine as the donor. The linking position of the thiophene unit to the DTPBT unit significantly influenced the photovoltaic performance. A power conversion efficiency of 7.55% with 1 mM CDCA as the co-adsorbent under simulated AM 1.5 G illumination was reached by the DSSC sensitized by the dye DTP4. These results indicate that the DTPBT-based organic dye is a promising candidate for efficient DSSCs.

1,2,5,6,9,10-Hexaalkoxyhexahelicenes 3 represent [3]star compounds with a helical core. A multistep synthetic concept for 3 is discussed, in which the final step 16→3 is a twofold oxidative photocyclization. The linearly conjugated compounds 16 contain stilbene and vinylnaphthalene units

Three novel metal-free organic dyes with dihydro-5H-dibenzo[b,f]azepine as a donor and cyanoacrylic acid as an anchoring unit were designed as an innovative linear skeleton of D-D-pi-A type of organic dyes. The conversion efficiency of the derived dye-sensitized solar cells is moderate. Among them, the dye with a hydroxy group as an additional anchoring moiety exhibited the highest UV-Vis absorption with a maximum molar extinction coefficient of 24,136 M-1 cm(-1) at lambda(max) = 458 nm and the best photovoltaic performance with an overall power conversion efficiency of 4.88%, while the dye with a carboxy group as an additional anchoring moiety exhibited the lowest conversion efficiency (4.52%). The results show that the dye loading on the film and photovoltaic performance of the dyes were influenced by the additional anchoring units. (C) 2013 Elsevier Ltd. All rights reserved.