Carrier transport assisted by dopants in doped poly(N-vinylcarbozole) light-emitting diodes

We have investigated the transient electroluminescence (EL) onset of the double-layer light-emitting devices made from poly(N-vinylcarbozole) (PVK) doped with 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) and tris(8-hydroxy-quinoline) aluminium (Alq(3)). For the double-layered device in which PVK was doped with 0.1 wt% DCJTB, the EL onset of PVK lags that of DCJTB and Alq(3), while the EL onset of DCJTB and Alq(3) is simultaneous. However, the EL emission of the double-layered device of PVK/Alq(3) originates only from Alq(3). The results show that DCJTB dopants can not only help to tunnel electrons from Alq(3) zone to PVK but can also assist electrons transfer in PVK under high electric field by hopping between DCJTB molecules or from DCJTB to PVK sites at a low doping concentration of 0.1 wt%. When the DCJTB doping concentration is 4.0 wt%, the EL onset of Alq(3) lags that of DCJTB. The difference in the EL onsets of DCJTB, Alq(3) and PVK is attributed to the slow build-up of the internal space charge in the vicinity of the interface between PVK and Alq(3). The electron potential difference of the interface between Alq(3) and PVK doped by DCJTB can be adjusted by changing the DCJTB doping concentration in double-layer devices.

Quantifying the effectiveness of SiO2/Au light trapping nanoshells for thin film poly-Si solar cells

In order to enhance light absorption of thin film poly-crystalline silicon (TF poly-Si) solar cells over a broad spectral range, and quantify the effectiveness of nanoshell light trapping structure over the full solar spectrum in theory, the effective photon trapping flux (EPTF) and effective photon trapping efficiency (EPTE) were firstly proposed by considering both the external quantum efficiency of TF poly-Si solar cell and scattering properties of light trapping structures. The EPTF, EPTE and scattering spectrum exhibit different behaviors depending on the geometric size and density of nanoshells that form the light trapping layer. With an optimum size and density of SiO2/Au nanoshell light trapping layer, the EPTE could reach up to 40% due to the enhancement of light trapping over a broad spectral range, especially from 500 to 800 nm.

Electropolymerized poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) film on ITO glass and its application in photovoltaic device

Poly(3,4-ethylenedioxythiopliene):poly(styrene sulfonate) (PEDOT:PSS) films have been electrochemically polymerized in situ on ITO glass substrate in boron trifluoride diethyl etherate electrolyte (BFEE). Cyclic voltammograms show good redox activity and stability of the PEDOT films. These films had been directly used to fabricate organic-inorganic hybrid solar cells with the structure of ITO/PEDOT/ZnO:MDMC-PPV/Al. The solar cells made of electrochemically polymerized films exhibit higher energy conversion efficiencies compared with that prepared by the spin-coating method, and the highest value is 0.33%. This in-situ electropolymerized method effectively simplifies fabricating procedures and may blaze a facile and economical route for producing high-efficiency solar cells.

Design and operation of integrated pilot-scale dimethyl ether synthesis system via pyrolysis/gasification of corncob

The integrated pilot-scale dimethyl ether (DME) synthesis system from corncob was demonstrated for modernizing utilization of biomass residues. The raw bio-syngas was obtained by the pyrolyzer/gasifier at the yield rate of 40-45 Nm(3)/h. The content of tar in the raw bio-syngas was decreased to less than 20 mg/Nm(3) by high temperature gasification of the pyrolysates under O-2-rich air. More than 70% CO2 in the raw bio-syngas was removed by pressure-swing adsorption unit (PSA). The bio-syngas (H-2/CO approximate to 1) was catalytically converted to DME in the fixed-bed tubular reactor directly over Cu/Zn/Al/HZSM-5 catalysts. CO conversion and space-time yield of DME were in the range of 82.0-73.6% and 124.3-203.8 kg/m(cat)(3)/h, respectively, with a similar DME selectivity when gas hourly space velocity (GHSV, volumetric flow rate of syngas at STP divided by the volume of catalyst) increased from 650 h(-1) to 1500 h(-1) at 260 degrees C and 4.3 MPa. And the selectivity to methanol and C-2(+) products was less than 0.65% under typical synthesis condition. The thermal energy conversion efficiency was ca. 32.0% and about 16.4% carbon in dried corncob was essentially converted to DME with the production cost of ca. (sic) 3737/ton DME. Cu (111) was assumed to be the active phase for DME synthesis, confirmed by X-ray diffraction (XRD) characterization.

Scale study of direct synthesis of dimethyl ether from biomass synthesis gas

We investigated the synthesis of dimethyl ether (DME) from biomass synthesis gas using a kind of hybrid catalyst consisting of methanol and HZSM-5 zeolite in a fixed-bed reactor in a 100 ton/year pilot plant. The biomass synthesis gas was produced by oxygen-rich gasification of corn core in a two-stage fixed bed. The results showed that CO conversions reached 82.00% and 73.55%, the selectivities for DME were 73.95% and 69.73%, and the space-time yields were 124.28 kg m- 3 h- 1 and 203.80 kg m- 3 h- 1 when gas hourly space velocities were 650 h- 1 and 1200 h- 1, respectively. Deoxidation and tar removal from biomass synthesis gas was critical to the stable operation of the DME synthesis system. Using single-pass synthesis, the H2/CO ratio improved from 0.98-1.17 to 2.12-2.22. The yield of DME would be increased greatly if the exhaust was reused after removal of the CO2.

酚酞型聚醚砜的化学改性及其性能研究

酚酞型聚醚砜（C-PES）是一种综合性能优异的工程塑料和功能材料，具有良好的成膜性、机械性能、热稳定性、化学稳定性和可加工性等。作为一种高性能的膜材料，酚酞型聚醚砜已被广泛的用于气体分离和水处理等领域。酚酞型聚醚砜侧链上含有可修饰的酯基，可通过各种方法，引入功能基团，对其进行化学改性，从而改善C-PES的各种性能，并扩展其应用领域。本论文设计制备了含有烷基、芳基、胺基以及磺酸基等功能基团的新型酚酞型聚醚砜材料，并对其性质进行了深入的研究： 1．通过各种基团修饰的二酚单体和二氯二苯砜的缩聚，合成了新型的含有不同酞侧基的Cardo型聚醚砜高分子材料，并对其性能进行了详细的研究。结果表明，所有聚合物都表现出极好的溶解性、耐热稳定性、成膜性、力学性能和气体分离性能；通过在酞侧基上引入了大体积的对叔丁基苯基，大大改善了材料的透气性和氧氮分离选择性；通过引入仲胺基，增大了聚合物链间作用力，从而提高了气体的分离选择性。此外，我们还对不同基团的引入对聚合物各种性能的影响作了详细的探讨，着重研究了聚合物的结构－性能关系。 2．利用含有胺基的双酚单体PPH-NH2、PPH和二氯二苯砜的共聚反应，成功合成了含有胺基的Cardo型聚醚砜高分子材料(PES-NH2)，并对材料的各种性质进行了表征。结果表明，由于胺基的引入，酚酞型聚醚砜的亲水性得到了大幅度的提高。 3．利用含胺基的Cardo双酚和磺化二氯二苯砜在碳酸钾作用下的缩聚反应，成功合成了含胺基的磺化Cardo型聚醚砜 (SPES-NH2)，并用于制备反渗透复合膜。通过优化制膜条件，我们利用界面聚合的方法成功制备了高水通量的TMC/ MPDA/SPES-NH2反渗透复合膜，并对复合膜的性能和结构进行了研究，重点讨论了膜的性能和结构、形貌之间的关系。结果表明，通过在复合膜活性层中引入强亲水性的磺酸基和全刚性主链的Cardo型聚醚砜，复合膜在保持较高盐截留率(97.3%)情况下，水通量得到了大幅度的提高，达到了51.2 L/m2.h。 4．合成了新型的全刚性芳香主链的两性聚电解质SPES-NH3+，并对其溶液性质和自组装行为进行了详细的研究。结果表明，在一定的溶液pH值下，两性聚电解质SPES-NH3+表现出聚阴离子的性质。另外，通过引入[BMIM]+离子屏蔽磺酸根负离子，我们在没有加入其它聚电解质的情况下，成功地制备了[BMIM]SPES-NH3+多层膜，并对多层膜表面性质进行了研究。结果表明，多层膜的厚度可由层数来控制，并且膜表面较平滑，其RMS值为6 nm。这种新的组装方式为构筑刚性主链的两性聚电解质多层膜提供了新的方法。

热可交联聚酰亚胺/高性能热塑性树脂共混体系的研究

1．热可交联聚酰亚胺／高性能热塑性树脂共混体系的研究聚苯硫醚［Poly（phenylene sulfide），PPS］是由刚性结构的苯环和柔性的硫醚连接起来，交替排列构成的线性高分子化合物，具有高的热稳定性、良好的耐化学药品性、优良的电绝缘性、耐老化性和阻燃性等综合性能优异的高性能树脂。聚醚矾〔Poly（ether sulfone），PES］是一种非结晶性的热塑性工程塑料一，具有优异的热稳定性、耐高温蠕变性及优异的物理机械性能。其高的玻璃化转变温度（Tg=225℃），使其可以在较高温度下作为结构材料使用。本论文研究了PPS/PES二元共混物的热性能和动态力学性能，并以热可控交联的低分子量多官能单体PMR-POI（聚醚酰亚胺）为界面增强剂，分别研究了POI与PPS、PES之间的接枝和／或交联反应，POI对PPS结晶行为的影响，POI对PES分子运动的影响和POI对PPS/PES共混体系的界面增强。主要结果如下：1．PPS/PES共混物相容性的特征在于选择性的部分相容，少量的非晶PPS分子可以扩散进入PES相区，相反的扩散过程则不会发生。2．PPS/PES共混物的热学性质和动态力学性能主要受连续相的控制。3．PPS相的性能主要受其结晶度的影响，因此能够改变其结晶度的因素均会改变PPS相的性质。4．光谱学和流变的证据表明，POI同PES，PPs共混过程中有接枝反应发生，分子链增长，分子量加大。这种接枝和／或交联反应的程度是热可控的。5．POI是PPS的增塑剂，成核剂和扩链剂，与POI共混使得PPS结晶速率增加，平衡熔点上升，表面折叠自由能降低。6；在PES/POI体系中Pol对PEs起到了增塑的作用，Tg降低，经高温热处理后Tg上升。因此，POI对PES性能的影响也是热可控的。7．PMR-POI能够在PPS/PES共混体系中有效地扩散并起到了降低分散相粒子的尺寸、增强界面的作用。它是该共混体系的有效界面增强剂。8．"高温退火既能够提高扩散速率也能够提高反应速率；二者相互竞争。2．马来酸配封端溉碳酸丙撑酯的研究二氧化碳与环氧丙烷交替共聚物（polypropylene careonate，PPC）是由二氧化碳活化并与环氧丙烷共聚而成的一类可完全生物降解的新型高分子材料，具有巨大的潜在应用价值。本论文讨论了马来酸配封端的聚碳酸丙撑酯（MA-PPC）和未封端的PPC的粘弹性、流变行为以及热降解和热分解行为，并得出如下结论：1．马来酸配封端抑制了PPC解拉链式的热分解和无规链断裂热降解，PPC的热稳定性和力学性能得到提高。2．PPC和MA-PPC在玻璃化转变温度有相似的自由体积分数，PPC的Tg比MA-PPC稍低。虽然PPC和MA-PPC玻璃化转变表观活化能E。和平均松弛时间T随温度升高单调降低，但PPC的分子运动对温度更敏感，而MA-PPC较稳定。马来酸配封端改变了PPC分子运动的特征及松弛行为，许多实验证据证明，这是由于封端后的PPC大分子链间的相互作用增强及分子链缠结密度增加。3．MA-PPC在70℃左右会发生脱水，实现大分子偶联反应并得到变温红外光谱、分子量成倍增加及线膨胀数据的有力支持。4．用零剪切粘度几。的方法测得PPC及MA－PPC加工过程中的热降解温度，它们分别为150℃和175℃，在此温度以上，η0降低速率的增加归因于大分子的主链断裂以及解拉链反应。5．测得了PPC的临界缠结分子量，它几乎是MA-PPC相应值（6613）的3倍。这表明马来酸配封端不仅改善了PPC的熔体弹性，而且也大大增强了PPC的缠结密度以及分子链间的相互作用。6．在本实验条件下在氮气和空气的气氛中，MA-PPC同PPC的热降解和热分解行为几乎一致，即在PPc的加土过程可以忽略氧气对其的影响。7．虽然MA-PPC的玻璃化温度在40℃左右，但在40℃-120℃的温度区间内，MA-PPC达不到粘流状态。8．没有剪切力时在120℃-150℃，30分钟内，MA-PPC几乎没有降解，在静态条件下，低于170℃时，MA-PPC的解拉链式降解是十分轻微的，当温度超过170℃，PPC降解相当严重。9．在热机械力存在的情况下，发生无规断链的机会增加，无规断链又会加速解拉链降解，因此实际加工中的加工窗口比静态下窄，MIA-PPC的加工窗口应为130℃-160℃。10．MA-PPC的热分解过程是一步完成的，热分解温度随升温速率的加快而提高，并计算出热分解的表观活化能为623.3KJ／mol。

稀土三元催化剂下二氧化碳/环氧丙烷/缩水甘油醚共聚物的合成与性能研究

为拓宽PPC的应用范围，本论文在CO2与PO的共聚反应中，引入第三单体缩水甘油醚（烯丙基缩水甘油醚AGE、丁基缩水甘油醚BGE和苯基缩水甘油醚GPE），制备得到不同结构和性能的二氧化碳共聚物。主要工作总结如下：1．在CO2与PO的共聚反应中，引入第三单体 AGE，合成了侧链带双键的官能化二氧化碳共聚物Pol（PO-co-CO2-co-AGE）；2．在CO2-PO-BGE的共聚反应中，控制PO／B GE的摩尔比，可制得不同结构和 性能的二氧化碳共聚物Poly（P0-co-CO2-co-BGE），其Tg为-26.8-36.1℃，大幅度拓展了二氧化碳共聚物的最低使用温度区间；3．在CO2与PO的共聚反应中，引入第三单体GPE，合成了侧链带刚性苯环的 二氧化碳共聚物Poty（PO-co-CO2-co-GPE），提高了聚合产物的热稳定性。