Performance improvement of conventional and inverted polymer solar cells with hydrophobic fluoropolymer as nonvolatile processing additive

The morphology of the photoactive layer critically affects the performance of the bulk heterojunction polymer solar cells (PSCs). To control the morphology, we introduced a hydrophobic fluoropolymer polyvinylidene fluoride (PVDF) as nonvolatile additive into the P3HT:PCBM active layer. The effect of PVDF on the surface and the bulk morphology were investigated by atomic force microscope and transmission electron microscopy, respectively. Through the repulsive interactions between the hydrophilic PCBM and the hydrophobic PVDF, much more uniform phase separation with good P3HT crystallinity is formed within the active layer, resulting enhanced light harvesting and improved photovoltaic performance in conventional devices. The PCE of the conventional device can improve from 2.40% to 3.07% with PVDF additive. The PVDF distribution within the active layer was investigated by secondary ion mass spectroscopy, confirming a bottom distribution of PVDF. Therefore, inverted device structure was designed, and the PCE can improve from 2.81% to 3.45% with PVDF additive. Our findings suggest that PVDF is a promising nonvolatile processing additive for high performance polymer solar cells.     

Luminescence and scintillation properties of rare-earth-doped LuF3 scintillation crystals

The Nd-doped and Er-doped LuF₃ single crystals were grown by the micro-pulling-down method to study their scintillation properties in the vacuum-ultraviolet (VUV) region. The doubly Nd–Er codoped single crystal was grown to study possibility of scintillation performance improvement by energy transfer from Er³⁺ to Nd³⁺ ions. The LiF flux was to avoid phase transition below melting temperature. The 1%Nd-doped sample showed the highest overall scintillation efficiency under X-ray excitation which was 7 times as high as that of the LaF₃:Nd 8% standard. The leading Nd³⁺ 5d–4f emission was situated at 176 nm, while the Er³⁺ 5d–4f emission for Er-doped samples was observed at 163 nm, which better matches the sensitivity of some VUV-sensitive photodetectors. The optimum Er concentration was determined to be around 1–3 mol%. No Er³⁺ 5d–4f emission was observed for the doubly Er,Nd-codoped sample due to energy transfer from the Er³⁺ to Nd³⁺ ions. Slight improvement of the light yield was observed in the doubly-doped sample with respect to the Nd-only doped one.     

浅谈降低电解槽氟化铝单耗的方法

氟化铝是电解生产中十分重要的原料，它对控制电解槽电解质温度，保持电解槽技术条件发挥着重要的作用。但随着电解生产成本的逐渐降低，氟化铝的消耗成为电解生产成本中的一项重要内容。本文就某分厂电解槽氟化铝添加的生产工艺、设备、控制以及管理等方面，提出降低氟化铝单耗的简要方法。     

真空钙热还原炉渣的综合利用研究

研究了从真空钙热还原炉渣中回收稀土的工艺条件；采用本工艺得到的合格稀土溶液，其回收率达65．41％；副产品氟化钙用作炼硅铁合金的助熔剂，使钙热还原炉渣得到综合利用。     

钕电解阳极过电位的测定

用慢扫描示波法测定了钕电解的阳极过电位 .考察了温度、阳极电流密度、Nd2 O3添加量、电解质组成等因素对阳极过电位的影响 ,探讨了降低阳极过电位的可能途径 .结果表明 ,阳极过电位随阳极电流密度的增加而增大 ,随温度的升高而减小 ,一定范围内 ,阳极过电位与阳极电流密度的对数呈线性关系 ,满足塔菲尔方程 ;电解质中LiF和Nd2 O3浓度增加 ,阳极过电位降低 ;适当控制阳极电流密度、升高温度、增加电解质中LiF和Nd2 O3的浓度并尽可能减小极间距 ,均有利于降低阳极过电位     

大尺寸氟化铅晶体的生长

描述了不用高真空条件，在通常的Ｂｒｉｄｇｍａｎ－Ｓｔｏｃｋｂａｒｇｅｒ炉中，用高温下的反应方法，消除了原料及生长炉内残存的Ｏ＾２－及ＯＨ＾－，生长出优质，大尺寸的β－ＰｂＦ２晶体。在晶体生长时，出现的主要问题是在晶体中的针状结构及开裂，但可通过控制条件来解决。     

Preparation and characterization of metal-complex imprinted PVDF hollow fiber membranes

Using nickel-2,2′-dipyridyl complex as a template, N-vinyl-2-pyrrolidone as the metal coordination functional monomer, and ethylene glycol dimethacrylate as the crosslinker, polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membrane as the supported membrane, metal complex imprinted polymeric membranes were prepared. The association constant of template-monomer interaction in the prepolymerization solution was estimated to be 4.38 × 10⁴ (L/mol)² by spectrophotometric titration analysis. The attenuated total reflection Fourier transform infrared spectroscopy and scanning electron micrograph characterization indicated that the surface of the support PVDF membrane was completely coated by the imprinted polymer layer after modification. The imprinted membranes exhibited the selective permeability for the template in certain nickel acetate solution. The molecularly imprinted membranes gave higher permeation separation factors at about pH 6, whereas increasing pressure would lower the separation ability. The effects of ion concentration, cations and counterions, ligand selectivity, pH, and trans-membrane pressure were investigated and the permeation performances of the imprinted membranes could be regarded as facilitated transport mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Direct-Ink-Writing of Electroactive Polymers for Sensing and Energy Storage Applications

Considering the high levels of materials used in the fields of electronics and energy storage systems, it is increasingly necessary to take into consideration environmental impact. Thus, it is important to develop devices based on environmentally friendlier materials and/or processes, such as additive manufacturing techniques. In this work, poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) are prepared by direct-ink-writing (DIW) by varying solvent evaporation temperature and fill density percentage. Different morphologies for both polymers are obtained, including dense films and porous membranes, as well as different electroactive β-phase content, thermal and mechanical properties. The dielectric constant and piezoelectric d₃₃ coefficient for dense films reaches up to 16 at 1 kHz and 4 pC N⁻¹, respectively for PVDF-HFP with a fill density of 80 and a solvent evaporation temperature of 50 °C. Porous structures are developed for battery separator membranes in lithium-ion batteries, with a highest ionic conductivity value of 3.8 mS cm⁻¹ for the PVDF-HFP sample prepared with a fill density of 100 and a solvent evaporation temperature of 25 °C, the sample showing an excellent cycling performance. It is demonstrated that electroactive films and membranes can be prepared by direct-ink writing suitable for sensors/actuators and energy storage systems.