嵌段共聚物/均聚物共混体系的结晶行为 I. 非球状共聚物胶束的作用

将Leibler, Whitmore和Mayes等近期关于非晶嵌段共聚物“稀固体溶液”的理论应用于嵌段聚共聚物结晶型“稀固体溶液”结晶行为的研究。发现球状共聚物胶束既可起成核剂作用, 也可起抑制成核作用。报导了当共聚物胶束由球形变为非球形时, 共聚物胶束的上述作用都会发生较大的变化, 并根据Leibler和Mayes分别提出的球形和非球形胶束理论解释了这一实验现象。     

Effect of emitter layer doping concentration on the performance of silicon thin film heterojunction solar cell

A novel type of n/i/i/p heterojunction solar cell with a-Si:H(15 nm)/a-Si:H(10 nm)/ epitaxial c-Si(47 μm)/epitaxial c-Si(3 μm) structure is fabricated by using the layer transfer technique, and the emitter layer is deposited by hot-wire chemical vapour deposition. The effect of the doping concentration of emitter layer S_d (S_d=PH₃/(PH₃+SiH₄+H₂)) on the performance of the solar cell is studied by means of current density-voltage and external quantum efficiency. The results show that the conversion efficiency of the solar cell first increases to a maximum value and then decreases with S_d increasing from 0.1% to 0.4%. The best performance of the solar cell is obtained at S_d = 0.2% with an open circuit voltage of 534 mV, a short circuit current density of 23.35 mA/cm², a fill factor of 63.3%, and a conversion efficiency of 7.9%.     

第一性原理研究Al-Cu-Li合金中T1相的腐蚀机理

利用密度泛函理论的第一性原理,讨论Al-Cu-Li合金中主要析出相T1相(Al6Cu4Li3)的表面性质,计算不同终结面的表面能和表面电子功函数,并探讨应力作用和常见合金元素对Al/T1界面的影响.结果表明:T1相的表面能与表面的原子排列有关,不同的表面通过应变释放重构,进而获得不同的表面能.表面电子功函数则与表面原子种类有关,由于Li的电负性最小,含Li原子的表面通常有较低的电子功函数,进而降低材料的耐蚀性.此外,在应力作用下,T1相一些表面的电子功函数变化与纯金属是相反的.压应力下T1相电子功函数降低,材料更加容易被腐蚀;张应力下T1相功函数增加,材料更加耐腐蚀.同时,通过计算Al/T1界面中Ag,Zn和Mg 3种合金元素的替位能,可以发现,这3种元素都有利于降低界面能,且Ag的作用最明显.     

烧绿石结构Y2-xMgxRu2O7-δ(x=0.05、0.1、0.15)的制备及其OER催化活性

采用溶胶-凝胶法制备系列的镁掺杂Y2-xMgxRu2O7-δ(YMRO?x,x=0.05、0.1、0.15)催化剂,通过X射线光电子能谱对其进行价态分析发现,采用小离子半径的Mg^2+取代烧绿石结构中处于A位的部分Y^3+,进一步增加了烧绿石结构中氧缺陷数量,也引发了部分Ru^4+转变为Ru^5+,释放电子到表面,促进了氧析出反应(OER)。其中YMRO?0.1催化剂的含氧缺陷浓度最高,其催化活性最高。在达到10 mA·cm^-2电流密度时,相比于RuO2(358 mV)、Y2Ru2O7-δ(294 mV),YMRO?0.1仅需施加265 mV过电位并且其Tafel斜率相对于RuO2(88 mV·dec^-1)和Y2Ru2O7-δ(64 mV·dec^-1)仅为45 mV·dec^-1。此外,由于氧空位增多,即活性位点增多,降低了自由基从金属位点脱附的吉布斯自由能,促进了OER催化性能。第一性原理表明,替位原子MgY与氧空位形成复合体,可以降低氧空位形成能,同时随着Mg^2+引入,带隙变小,电荷迁移能也随之变小,进而可以得到更高的催化活性。     

Effect of emitter layer doping concentration on the performance of a silicon thin film heterojunction solar cell

A novel type of n/i/i/p heterojunction solar cell with a-Si:H(15nm)/a-Si:H(10nm)/ epitaxial c-Si(47μm)/epitaxial c-Si(3μm) structure is fabricated by using the layer transfer technique, and the emitter layer is deposited by hot wire chemical vapour deposition. The effect of the doping concentration of the emitter layer S d (Sd =PH3 /(PH3 +SiH4 +H2 )) on the performance of the solar cell is studied by means of current density-voltage and external quantum efficiency. The results show that the conversion efficiency of the solar cell first increases to a maximum value and then decreases with S d increasing from 0.1% to 0.4%. The best performance of the solar cell is obtained at S d = 0.2% with an open circuit voltage of 534 mV, a short circuit current density of 23.35mA/cm2 , a fill factor of 63.3%, and a conversion efficiency of 7.9%.