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Three novel metal-free organic dyes IT , IPT and IQT , containing a dipentyldithieno[3,2- f :2′,3′- h ]quinoxaline ( DPQ ) unit as the π-bridge were synthesized and the impacts of the auxiliary acceptors on the photovoltaic performances were studied. IQT with 2,3-dipentylquinoxaline as the auxiliary acceptor exhibited the highest efficiency of 7.98%, with a short-circuit photocurrent density of 16.87 mA cm −2 , an open-circuit photovoltage of 0.71 V, and a fill factor of 0.67, under standard global AM 1.5G solar light condition. IPT with the strongest electron-withdrawing group (2,3-dipentylpyridopyrazine) as the auxiliary acceptor could red-shift the absorption range, but showed the weakest performance, which might be due to the electron trap of the 2,3-dipentylpyridopyrazine unit. The results show that incorporating auxiliary acceptor with moderate electron-deficient ability can extend the absorption range and adjust the molecular orbital energy levels, improving the photovoltaic performance. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Four novel D–π–A–π–A metal-free organic dyes Q1-Q4 were synthesized and the impacts of the auxiliary acceptors on the photovoltaic performances were studied. Q2 with quinoxaline as the auxiliary acceptor exhibited the best photovoltaic performance due to its highest short-circuit photocurrent density (17.22 mA cm −2 ), leading to a power conversion efficiency of 7.42% under simulated AM 1.5 G illumination. Q1 with the strongest electron withdrawing group (pyrazino[2,3- g ]quinoxaline) as the auxiliary acceptor showed the weakest performance, which can be attributed to electron trap and mismatch of energy-level. The results showed that the different electron-withdrawing property of auxiliary units significantly influenced the absorption, energy levels and photovoltaic performance. Incorporating auxiliary acceptor with moderate electron-deficient ability can extend the absorption range and adjust the molecular orbital energy levels, resulting in better photovoltaic performance. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 ( ε ), but exhibited π-stacked aggregation on the TiO 2 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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Fluorescence imaging-guided photodynamic therapy (PDT) is considered as an ideal alternative strategy to treat tumors. However, insufficient supply of oxygen in solid tumor tissue, aggregation-caused quenching (ACQ) of photosensitizers (PSs), poor targeting-specificity of cancer cells and short wavelengths of emission are representative obstacles for effective PDT. In this paper, three D-π-A structured PSs TSB-OH , TSBPy-OH , TSBPy-DNT with aggregation induced emission (AIE) properties and integrated type I and type II ROS generation were synthesized by modulating distinct acceptor units. Among them, TSBPy-OH is optimal with multiple advantages including near-infrared emission, good biocompatibility, remarkably intracellular ROS production ability, mitochondria targeting capability inducing cell apoptosis and enhancing PDT, and long-term tumor retention ability for imaging-guided photodynamic therapy. More importantly, efficient in vitro cancer cells damage, in vivo tumor ablation and ignorable damage in major organs during PDT are demonstrated, suggesting potential capability of TSBPy-OH in safe and effective fluorescence imaging-guided PDT. This successful example of AIE theranostics design would provide a reference for the modification of D-π-A structure organic AIEgens. [Display omitted] • Three organic photosensitizers with AIE characteristic were developed. • TSBPy-OH exhibited excellent type Ⅰ and type Ⅱ ROS generation ability. • TSBPy-OH showed mitochondria targeting capability and could induce cell apoptosis. • TSBPy-OH could effectively inhibit tumor growth and had good biological safety. [ABSTRACT FROM AUTHOR]

Abstract Four novel benzotriazole-based donor-acceptor-donor (D-A-D) type hole transport materials (HTMs) BTA1-2 and DT1-2 are synthesized to investigate the effect of the acceptors on the photovoltaic performance of perovskite solar cells (PSCs). The acceptors include nonfused core (thiophene-benzotriazole-thiophene) and fused core (dithienopyrrolobenzotriazole, DTBT). Systematical investigation reveals that the acceptor greatly influences the absorption, energy level, hole transfer and extraction, and photovoltaic performances of the HTMs. The dopant-free HTMs DT1-2 with DTBT core exhibit better hole transfer and extraction performance, and then obtain better photovoltaic performance than that of BTA1-2. Especially, the PSC using DT2 without any dopants obtains a power conversion efficiency of 13.22%, which is outperforming than that of spiro-OMeTAD (10.41%). When doping with Li-TFSI/TBP (lithium bis(trifluoromethylsulphonyl)imide/tert-butylpyridine), DT2 -based cell achieves an improved efficiency of 15.77%. In addition, the different alkoxyl chain lengths on triphenylamine has a significant impact on the conductivity, hole mobility, hole extraction, and photovoltaic performance. The stability testing of the PSCs shows that the four HTMs based devices display improved stability than spiro-OMeTAD. These results certify that the fused acceptor core DTBT is a promising core for efficient D-A-D type HTMs towards PSCs. Graphical abstract Image 1 Highlights • Novel D-A-D types HTMs with different acceptor cores were reported. • Acceptor core of the HTMs greatly influences the performance of the PSCs. • DT-2 based PSC obtains a power conversion efficiency of 15.77%. • DT1-2 exhibit better conductivity and hole mobility than spiro-OMeTAD. [ABSTRACT FROM AUTHOR]

Abstract A novel colorimetric fluorescent chemosensor TP1 with a D-π-A structure for the detection of (cyanide) CN− has been developed. TP1 is capable of showing high selectivity and sensitivity towards CN− over a wide range of other interfering anions. After reaction with CN−, TP1 shows a significant blue-shift of absorption peak from 514 to 437 nm, which induces color changes from amaranth to yellow. Non-fluorescent TP1 upon interaction with CN− exhibits a ca. 17-fold fluorescence enhancement at 551 nm, resulting in strong orange emission. The sensing mechanism of TP1 recognizes CN− which undergoes a nucleophilic addition reaction. Moreover, the detection limit of the probe TP1 towards CN− is 1.4 × 10−8 M, which is far lower than the WHO guideline of 1.9 μM cyanide for drinking water. In addition, the cell imaging experiments certify that TP1 can be successfully applied as a bioimaging agent for monitoring CN− in pheochromocytoma cell (PC12). Graphical abstract Image 1 Highlights • Probe TP1 with D-π-A featured structure for CN− was developed. • TP1 can detect cyanide with high sensitivity and selectivity. • The detection limit of TP1 towards CN− was 1.4 × 10−8 M. • TP1 can be applied in cell imaging with turn-on emission and low cytotoxicity. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is a promising treatment for cancer, but still faces challenges. For example, the residual photosensitizers (PSs) can cause toxic effects on normal tissues. Thus, it is of great importance to change the PS into safe compounds in or after PDT process. In this work, a novel PS NTPy was synthesized and successfully applied for cancer therapy. NTPy with aggregation-induced emission (AIE) characteristics shows high reactive oxygen species generation efficiency and exhibits a strong fluorescence emission in 678 nm. In addition, NTPy shows excellent mitochondria targeting capacity. In hypoxic microenvironment, NTPy is degraded into TPy via the reduction caused by nitroreductase. TPy shows very little PDT activities and low fluorescence emission. Therefore, NTPy can detect the hypoxic microenvironment of tumor through fluorescence "turn-off" response. More importantly, NTPy can reduce the side effects of PS on normal tissues after effective PDT treatment. This work provides a new strategy for intelligent PDT treatment and increases the biological safety of PDT. • A new aggregation-induced emission (AIE) photosensitizer NTPy was developed. • NTPy showed excellent mitochondria targeting and high ROS generation capacities. • NTPy could be degraded into TPy via the reduction by NTR in hypoxic condition. • TPy showed very little PDT activity and low fluorescence emission. [ABSTRACT FROM AUTHOR]

Abstract: 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–π–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 λ 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. [Copyright &y& Elsevier]

Development of multifunctional probes that can be simultaneously utilized for both efficient hydrogen sulfide detection and photodynamic therapy in cancer cells is in high demand but remains worldwide challenge. Herein, a fluorescent probe DB2T based on a BODIPY structure for H 2 S fluorescence "turn-on" detection together with light sensitive anticancer capacity has been designed and synthesized. The probe DB2T features high selectivity towards H 2 S, excellent low detection limit (6.39 nM), and good biocompatibility. Importantly, the probe DB2T has been satisfactorily applied in fluorescence imaging of exogenous H 2 S in zebrafish, and successfully employed in fluorescence imaging of endogenous H 2 S in HCT116 cell and tumor tissues. Moreover, evaluation of the phototherapy effect demonstrates that the probe DB2T performs well as a photosensitizer for photodynamic ablation of HCT116 cancer cells upon white light irradiation. This work should facilitate significant advances in rational design of fluorescence systems for H 2 S detection and even in the diagnosis and treatment of H 2 S related diseases. [Display omitted] • A novel fluorescent probe DB2T for hydrogen sulfide detection was developed. • DB2T can detect H 2 S with excellent selectivity and low detection limit (6.39 nM). • DB2T can detect endogenous H 2 S in HCT116 cell with fluorescence turn-on. • DB2T performs well for photodynamic therapy of HCT116 cancer cells. [ABSTRACT FROM AUTHOR]