Effect of electron-donor ancillary ligands on the heteroleptic ruthenium complexes: synthesis, characterization, and application in high-performance dye-sensitized solar cells.

Three heteroleptic ruthenium complexes, RC-15, RC-16 and RC-22, with sulfur- or oxygen-containing electron-donor, phenylpyridine-based ancillary ligands, are synthesized. The influence of the different electron donors-the acyclic electron donors methylthio and methoxyl, and the cyclic electron donor methylenedioxy-on the photophysical and electrochemical behavior in dye sensitizers and photovoltaic performance in DSSCs are investigated. Compared to the conventional dye N3, all the dyes demonstrate superior performance in the form of molar absorptivity, photocurrent density (J(SC)) and conversion efficiency (η). The DSSCs based on RC-15 and RC-16, with only a two-atom change in the acyclic electron donor, exhibit analogous photovoltaic performance (9.28% for RC-15 and 9.32% for RC-16). The highest photocurrent density (19.06 mA cm(-2)) and conversion efficiency (9.74%) are recorded for RC-22, which contains the cyclic electron donor. Transient absorption (TAS) and time-resolved photoluminescence (TRPL) measurements are carried out to investigate the sensitizers' regeneration and the behavior of excited electron decay kinetics. Furthermore, electrochemical impedance spectroscopy (EIS) is operated to explain the charge recombination and the electron lifetime. These consequences reveal substantial dependences on the different configurations of the electron-donor ancillary ligands.

Efficient Sb2S3 and Low Se Content Sb2SeyS3-y Indoor Photovoltaics.

Herein, the precise fabrication of Sb2S3 and low Se content Sb2SeyS3-y indoor photovoltaics is reported, and a measurement protocol for photovoltaic performance is suggested and applied. Insertion of the SnO2 buried layer decreases the thickness and parasitic absorption of the CdS layer. The introduction of minor Se into Sb2S3 and the use of spiro-OMeTAD:TMT-TTF improve the charge transport of indoor photovoltaics. Using a white light-emitting diode (LED) under illuminance of 1000, 500, and 200 lx with color temperatures of 3347 and 6103 K, indoor photovoltaics with fluorine doped tin oxide (FTO)/SnO2 (17 nm)/CdS (20 nm)/Sb2S3/spiro-OMeTAD:TMT-TTF/Au exhibit power conversion efficiency (PCE) values of 17.59, 16.66, 16.44, 16.56, 15.50, and 14.07%, respectively. Indoor photovoltaics with FTO/SnO2 (17 nm)/CdS (20 nm)/Sb2SeyS3-y(Sb/S/Se = 1:1.42:0.06)/spiro-OMeTAD:TMT-TTF/Au achieve PCE values of 18.53, 17.62, 17.07, 17.30, 16.24, and 15.38%, respectively. The PCE values of 17.59, 16.66, and 16.44% are the highest values reported for Sb2S3 indoor photovoltaics, and the other PCEs are all reported for the first time. Considering the trillion-dollar-sized market from the Internet of Things (IoT), this work can further bring an unprecedented thrust to the development of self-powered IoT devices by harvesting energy from indoor photovoltaics, thereby realizing the recycling of photon energy and reducing the use of batteries and the emission of CO2.

New bithiazole-based sensitizers for efficient and stable dye-sensitized solar cells.

A series of new push-pull organic dyes (BT-I-VI), incorporating electron-withdrawing bithiazole with a thiophene, furan, benzene, or cyano moiety, as π spacer have been synthesized, characterized, and used as the sensitizers for dye-sensitized solar cells (DSSCs). In comparison with the model compound T1, these dyes containing a thiophene moiety between triphenylamine and bithiazole display enhanced spectral responses in the red portion of the solar spectrum. Electrochemical measurement data indicate that the HOMO and LUMO energy levels can be tuned by introducing different π spacers between the bithiazole moiety and cyanoacrylic acid acceptor. The incorporation of bithiazole substituted with two hexyl groups is highly beneficial to prevent close π-π aggregation, thus favorably suppressing charge recombination and intermolecular interaction. The overall conversion efficiencies of DSSCs based on bithiazole dyes are in the range of 3.58 to 7.51 %, in which BT-I-based DSSCs showed the best photovoltaic performance: a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 81.1 %, a short-circuit photocurrent density (J(sc)) of 15.69 mA cm(-2), an open-circuit photovoltage (V(oc)) of 778 mV, and a fill factor (ff) of 0.61, which correspond to an overall conversion efficiency of 7.51 % under standard global AM 1.5 solar light conditions. Most importantly, long-term stability of the BT-I-III-based DSSCs with ionic-liquid electrolytes under 1000 h of light soaking was demonstrated and BT-II with a furan moiety exhibited better photovoltaic performance of up to 5.75 % power conversion efficiency.

Stable dyes containing double acceptors without COOH as anchors for highly efficient dye-sensitized solar cells.

The electron acceptor 2-(1,1-dicyanomethylene) rhodanine is a promising alternative to cyanoacrylic acid as an anchoring group for organic dyes. For example, the RD-II-based dye-sensitized solar cell has an overall conversion efficiency of 7.11 % and long-term stability.

Two-dimensional triphenylene cored hole-transporting materials for efficient perovskite solar cells.

Two organic hole-transporting materials comprising a two-dimensional triphenylene core and methoxyl-arylamine terminal units are developed and applied in perovskite solar cells. Enhanced photovoltaic and stability performance are obtained using TPH-T compared with those of spiro-OMeTAD.

Tetraphenylmethane-Arylamine Hole-Transporting Materials for Perovskite Solar Cells.

A new class of hole-transporting materials (HTM) containing tetraphenylmethane (TPM) core have been developed. After thermal, charge carrier mobility, and contact angle tests, it was found that TPA-TPM (TPA: arylamine derivates side group) showed higher glass-transition temperature and larger water-contact angle than spiro-OMeTAD with comparable hole mobility. Photoluminescence and impedance spectroscopy studies indicate that TPA-TPM's hole-extraction ability is comparable to that of spiro-OMeTAD. SEM and AFM results suggest that TPA-TPM has a smooth surface. When TPA-TPM is used in mesoscopic perovskite solar cells, power conversion efficiency comparable to that of spiro-OMeTAD is achieved. Notably, the perovskite solar cells employing TPA-TPM show better long-term stability than that of spiro-OMeTAD. Moreover, TPA-TPM can be prepared from relatively inexpensive raw materials with a facile synthetic route. The results demonstrate that TPM-arylamines are a new class of HTMs for efficient and stable perovskite solar cells.

Superior Light-Harvesting Heteroleptic Ruthenium(II) Complexes with Electron-Donating Antennas for High Performance Dye-Sensitized Solar Cells.

Three heteroleptic polypyridyl ruthenium complexes, RC-41, RC-42, and RC-43, with efficient electron-donating antennas in the ancillary ligands were designed, synthesized, and characterized as sensitizers for dye-sensitized solar cell. All the RC dye sensitizers showed remarkable light-harvesting capacity and broadened absorption range. Significantly, RC-43 obtained the lower energy metal-ligand charge transfer (MLCT) band peaked at 557 nm with a high molar extinction coefficient of 27 400 M(-1) cm(-1). In conjunction with TiO2 photoanode of submicrospheres and iodide-based electrolytes, the DSSCs sensitizing with the RC sensitizers, achieved impressively high short-circuit current density (19.04 mA cm(-2) for RC-41, 19.83 mA cm(-2) for RC-42, and 20.21 mA cm(-2) for RC-43) and power conversion efficiency (10.07% for RC-41, 10.52% for RC-42, and 10.78% for RC-43). The superior performances of RC dye sensitizers were attributed to the enhanced light-harvesting capacity and incident-photon-to-current efficiency (IPCE) caused by the introduction of electron-donating antennas in the ancillary ligands. The interfacial charge recombination/regeneration kinetics and electron lifetime were further evaluated by the electrochemical impedance spectroscopy (EIS) and transient absorption spectroscopy (TAS). These data decisively revealed the dependences on the photovoltaic performance of ruthenium sensitizers incorporating electron-donating antennas.

Mesoporous TiO2 Yolk-Shell Microspheres for Dye-sensitized Solar Cells with a High Efficiency Exceeding 11%.

Yolk-shell TiO2 microspheres were synthesized via a one-pot template-free solvothermal method building on the aldol condensation reaction of acetylacetone. This unique structure shows superior light scattering ability resulting in power conversion efficiency as high as 11%. This work provided a new synthesis system for TiO2 microspheres from solid to hollow and a novel material platform for high performance solar cells.

Photovoltaic performance of bithiazole-bridged dyes-sensitized solar cells employing semiconducting quantum dot CuInS2 as barrier layer material.

In this work, the quantum dot CuInS2 layer was deposited on TiO2 film using successive ionic layer absorption and reaction (SILAR) method, and then two bithiazole-bridged dyes (BTF and BTB) were sensitized on the CuInS2/TiO2 films to form dye/CuInS2/TiO2 photoanodes for DSSCs. It was found that the quantum dots CuInS2 as an energy barrier layer not only could effectively improve open-circuit voltage (Voc) of solar cell, but also increase short-circuit photocurrent (Jsc) compared to the large decrease in Jsc of ZnO as energy barrier layer. The electrochemical impedance spectroscopy (EIS) measurement showed that the CuInS2 formed a barrier layer to suppress the recombination from injection electron to the electrolyte and improve open-circuit voltage. Finally, the open-circuit voltage increased about 22 and 27mV for BTF and BTB-/CuInS2/TiO2-based cells, the overall conversion efficiencies also reached to 7.20% and 6.74%, respectively.

Benzotriazole-bridged sensitizers containing a furan moiety for dye-sensitized solar cells with high open-circuit voltage performance.

Two new benzotriazole-bridged sensitizers are designed and synthesized (BTA-I and BTA-II) containing a furan moiety for dye-sensitized solar cells (DSSCs). Two corresponding dyes (BTA-III and BTA-IV) with a thiophene spacer were also synthesized for comparison. All of these dyes performed as sensitizers for DSSCs, and the photovoltaic performance data of these benzotriazole-bridged dyes showed a high open-circuit voltage (V(oc): 804-834 mV). Among the four dyes, DSSCs based on BTA-II, with a furan moiety and branched alkyl chain, showed the highest V(oc) (834 mV), a photocurrent density (J(sc)) of 12.64 mA cm(-2), and a fill factor (FF) of 0.64, corresponding to an overall conversion efficiency (η) of 6.72%. Most importantly, long-term stability of the BTA-I-IV-based DSSCs with ionic-liquid electrolytes under 1000 h light-soaking was demonstrated, and BTA-II exhibited better photovoltaic performance of up to 5.06% power conversion efficiency.

Series of new D-A-π-A organic broadly absorbing sensitizers containing isoindigo unit for highly efficient dye-sensitized solar cells.

In this work, six new D-A-π-A sensitizers (ID1-ID6), with triarylamine as the electron donor; isoindigo as a auxiliary electron withdrawing unit; thiophene, furan, and benzene as the linker; and cyanoacrylic acid as the anchoring group, were synthesized through simple synthetic procedures and with low cost. Their absorption spectra were broad with long wavelength absorption maximum approximately at 589 nm and the absorption onset at 720 nm on the TiO(2) film. Electrochemical experiments indicate that the HOMO and LUMO energy levels can be conveniently tuned by alternating the donor moiety and the linker. All of these dyes performed as sensitizers for the DSSCs test under AM 1.5 similar experimental conditions, and a maximum overall conversion efficiency of 5.98% (J(sc) = 14.77 mA cm(-2), V(oc) = 644 mV, ff = 0.63) is obtained for ID6-based DSSCs when TiO(2) films were first immersed for 6 h in 20 mM CDCA ethanol solution followed by 12 h of dipping in the dye CH(2)Cl(2) solution. Electrochemical impedance measurement data implies that the electron lifetime can be increased by coadsorption of CDCA, which leads to a lower rate of charge recombination and thus improved V(oc).

Chronic electromagnetic field exposure decreases HSP70 levels and lowers cytoprotection.

Electromagnetic field (EMF) exposures have been shown to induce heat shock proteins (HSPs), which help to maintain the conformation of cellular proteins during periods of stress. We have previously reported that short-term exposure of chick embryos to either 60 Hz (extremely low frequency: ELF), or radio-frequency (RF: 915 MHz) EMFs induce protection against hypoxia. Experiments presented in the current report are based on a study in which long-term (4 days), continuous exposure to ELF-EMFs decreased protection against ultraviolet radiation. Based on this result, it was hypothesized that de-protection against hypoxia should also occur following long-term, continuous, or daily, repeated exposures to EMFs. To test this hypothesis, chick embryos were exposed to ELF-EMFs (8 microT) continuously for 4 days, or to ELF or RF (3.5 mW incident power)-EMFs repeated daily (20, 30, or 60 min once or twice daily for 4 days). Several of the exposure protocols yielded embryos that had statistically significant decreases in protection against hypoxic stress (continuous and 30 or 60 min ELF twice daily; or 30 or 60 min once daily RF). This is consistent with our finding that following 4 days of ELF-EMF exposure, HSP70 levels decline by 27% as compared to controls. In addition, the superposition of ELF-EMF noise, previously shown to minimize ELF-EMF induced hypoxia protection, inhibited hypoxia de-protection caused by long term, continuous ELF or daily, repeated RF exposures. This EMF-induced decrease in HSP70 levels and resulting decline in cytoprotection suggests a mechanism by which daily exposure (such as might be experienced by mobile phone users) could enhance the probability of cancer and other diseases.