Two new multibranched thiophene-based triarylamine derivatives with 1,3,5-triazine core are synthesized and characterized. Their one-and two-photon absorption properties and aggregation-induced emission effect have been investigated. Both the STAPA-based compounds are AIE active. The two-photon absorption (2PA) cross sections measured by the open aperture Z-scan technique are determined to be 620 and 1610 GM for STAPA-a and STAPA-b in chloroform,respectively, which dramatically increase with the introduction of alkyl chains. The relationship between their structures and properties on one-and two-photon absorption and aggregation-induced emission is discussed, which allows us to examine the effect of introducing alkyl chains. In addition, solvent effects also show a significant influence on the 2PA cross section. The two compounds with excellent AIE and 2PA properties provide attractive alternatives for the biophotonic materials.
GAO YuTingZHANG HaoJIANG TaoYANG JiLI BoLI ZhenHUA JianLi
Functional organic dyes have promising prospect in dye-sensitized solar cells as a crucial element, of which sensitizers based on donor-π-acceptor are the most important dyes. On the basis of the structures of the aromatic amine donors such as triphenylamine and indoline, this paper reviews the photoelectric conversion properties of organic sensitizers since 2008, and highlights research work in our laboratory in this area.
A distinctive method is proposed by simply utilizing ultrasonic technique in Ti02 electrode fabrication in order to improve the optoelectronic performance of dye-sensitized solar cells （DSSCs）. Dye molecules are at random and single molecular state in the ultrasonic field and the ultrasonic wave favors the diffusion and adsorption processes of dye molecules. As a result, the introduction of ultrasonic technique at room temperature leads to faster and more well-distributed dye adsorption on TiO2 as well as higher cell efficiency than regular deposition, thus the fabrication time is markedly reduced. It is found that the device based on 40 kHz ultrasonic （within 1 h） with N719 exhibits a Voc of 789 mV, Jsc of 14.94 mA]cm2 and fill factor （FF） of 69.3, yielding power conversion efficiency （PCE） of 8.16%, which is higher than device regularly dyed for 12 h （PCE = 8.06%）. In addition, the DSSC devices obtain the best efficiency （PCE = 8.68%） when the ultrasonic deposition time increases to 2.5 h. The DSSCs fabricated via ultrasonic technique presents more dye loading, larger photocurrent, less charge recombination and higher photovoltage. The charge extraction and electron impedance spectroscopy （EIS） were performed to understand the influence of ultrasonic technique on the electron recombination and performance of DSSCs.
Room temperature molten salt 1-methyl-3-（trimethylsilyl）methyl-imidazolium iodide （MSII） was used for io-dide sources in dye-sensitized solar cells with an organic sensitizer 2-cyano-3-[5-[4-[3-[4-（4-（N,N-bis（4-methoxy-phenyl）amino）phenyl）phenyl]-2,5-di-n-butyl-pyrrolo[3,4-c]pyrrole-1,4-dione]phenyl] furan-2-yl] acrylic acid （DPP-I） as light harvester. With an optimized electrolyte （MSII ： I2 ： BI ： GuNCS=24 ： 2 ： 2 ： 0.4, BI and GuCNS are short for benzimidazole and guanidine thiocyanate, respectively）, photovoltaic parameters （Jsc, Voc, and ff） of device are 8.97 mA·cm^-2, 600 mV and 0.61, respectively, yielding a maximum overall photo-to-energy con-version efficiency （17） of 3.23%. And then the charge-transfer mechanism of devices was deeply analyzed with elec- trochemical impedance spectroscopy （EIS） in the dark.
