Improved performance of P3HT：PCBM solar cells by both anode modification and short-wavelength energy utilization using Tb（aca）3phen

The performance of P3HT:PCBM solar cells was improved by anode modification using spin-coated Tb(aca)3phen ultrathin films. The modification of the Tb(aca)3phen ultrathin film between the indium tin oxide(ITO) anode and the PEDOT:PSS layer resulted in a maximum power conversion efficiency(PCE) of 2.99% compared to 2.66% for the reference device, which was due to the increase in the short-circuit current density(Jsc). The PCE improvement could be attributed to the short-wavelength energy utilization and the optimized morphology of the active layers. Tb(aca)3phen with its strong down-conversion luminescence properties is suitable for the P3HT:PCBM blend active layer, and the absorption region of the ternary blend films is extended into the near ultraviolet region. Furthermore, the crystallization and the surface morphology of P3HT:PCBM films were improved with the Tb(aca)3phen ultrathin film. The ultraviolent–visible absorption spectra,atomic force microscope(AFM), and X-ray diffraction(XRD) of the films were investigated. Both anode modification and short-wavelength energy utilization using Tb(aca)3phen in P3HT:PCBM solar cells led to about a 12% PCE increase.     

单扫描示波极谱法测定药物中的苯妥英钠

建立了测定苯妥英钠的新方法。在0．016mol／L B-R(pH 7．0)缓冲溶液中,本妥英钠产生一还原波,峰电位为-1．18V。该还原波二阶导数峰电流与苯妥英钠浓度呈线性,线性范围为2．5～50μg／mL,检出限为2．0μg／mL。该方法用于片剂中笨妥英钠含量的测定,结果满意。     

Analysis of Polymorphism and Dual Crystalline Morphologies in Poly(hexamethylene terephthalate)

Summary: The polymorphisms in poly(hexamethylene terephthalate) (PHT), along with their associated melting and spherulite morphologies, were examined by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and polarized‐light microscopy (PLM). The morphology and crystal cells were dependent on the temperature of crystallization. When melt‐crystallized at low temperatures (90–135 °C), PHT showed at least five melting peaks and two re‐crystallization peaks upon DSC scanning, and the samples displayed various fractions of both α and β crystals. However, only a single melting peak was obtained in PHT melt‐crystallized at 140 °C or above, which displayed a single type of β crystal. In addition, two different forms of spherulites were identified in melt‐crystallized PHT, with one being a typical Maltese‐cross spherulite containing the α crystal, and the other being a dendrite‐type packed mainly with the β crystal. This study provides timely evidence for a critical interpretation of the relationship between multiple melting and polymorphisms (unit cells and spherulites) in polymers, including semi‐crystalline polyesters.

WAXD diffractograms for PHT melt‐crystallized at 140 °C, revealing a single type of β‐crystal cell.     

Charge transport in monolayer poly（3-hexylthiophene） thin-film transistors

It is found that ultrathin poly（3-hexylthiophene） （P3HT） film with a 2.5 nm-thick layer exhibits a higher mobility of 5.0× 10-2 cm2/V-s than its bulk counterpart. The crystalline structure of the as-fabricated ultrathin P3HT layer is verified by atomic force microscopy as well as grazing incidence X-ray diffraction. Transient measurements of the as-fabricated transistors reveal the influence of the interface traps on charge transport. These results are explained by the trap energy level distribution at the interface manipulated by layers of polymer film.     

Poly(hexamethylene terephthalate-co-caprolactone) copolymers: Influence of cycle size on ring-opening polymerization

Poly(hexamethylene terephthalate) was cyclo-depolymerized in solution by heating to yield a fraction of cyclic oligomers of hexamethylene terephthalate (c(HT)_2-5) with a content around to 95% in dimer to pentamer. Ring-opening polymerization in the melt of c(HT)_2-5, either neat or in mixtures with ε-caprolactone (CL) covering a range of HT/CL ratios from 9/1 to 1/9 was carried out to produce polyesters with molecular weights above 30,000 in high yields. The copolyesters had a comonomer composition according to the feed and the microstructure evolved from random to blocky as the content in CL increases. The thermal and mechanical properties of the copolyesters were evaluated for a variety of compositions. Results obtained in this work were compared to those previously obtained by us in the ring-opening copolymerization of CL with a cyclic oligomeric fraction enriched in hexamer and heptamer (c(HT)_6-7). Although the polyesters resulting from the use of these two fractions were similar, significant differences were found in polymerization rate evidencing a lower reactivity of c(HT)_n with decreasing values of n.