溶胶-凝胶法制备ZnO:Al(ZAO)薄膜的光电特性

采用溶胶-凝胶法在石英衬底上制备了ZAO薄膜.在氮气气氛下进行退火处理,X射线衍射(XRD)谱表明ZAO薄膜具有六角纤锌矿的晶体结构.对ZAO薄膜的光电特性进行测量,结果显示薄膜的光致发光峰发生蓝移,喇曼光谱随A1掺杂浓度的变化发生相应的改变.薄膜的电导率在Al浓度为1%,700℃退火处理时达到最高值.     

夏热冬冷地区既有公共建筑节能方案的设计

根据夏热冬冷地区的气候特征与公共建筑的能耗特点,为减少空调和照明系统能耗进行了相关的节能方案设计.由于空调系统能耗是建筑总能耗中最重要的一个部分,重点分析了与空调系统能耗密切相关的围护结构的节能方案,包括外墙设计、窗体设计和外遮阳设计;简述了新风系统的热回收技术;提出了用LED技术代替现有节能灯的方案.改造后的能耗分析结果显示,提出的节能设计方案针对性强,对夏热冬冷地区公共建筑节能有着巨大的推动作用,并进一步强调了节能理念的重要性.     

Composition Waves in Solution-Processed Organic Films and Its Propagations from Kinetically Frozen Surface Mesophases

Organic thin films deposited from solution attract wide interest for next-generation (opto-)electronic and energy applications. During solvent evaporation, the phase evolution dynamics for different components at different locations are not synchronic within the incrementally concentrated liquid films, determining the final anisotropic morphology and performance. Herein, by examining tens of widely investigated optoelectronic organic films, the general existence of composition wave propagating along the surface-normal direction upon solidification is identified. The composition wave is initiated by a few nanometers thick surface mesophase kinetically forming at the foremost stage of phase transition, and afterward propagates toward the substrate during solvent evaporation. The composition waves exhibit well-defined wave properties, including spatial wavelength, period, amplitude, and propagation velocity. These wave properties are closely correlated with the evaporation rate and the diffusion rate of organic molecules, which determines the dynamically varied local composition gradient along the surface-normal direction. Such composition waves are commonly found for more than 80% of randomly examined solution-processed thin films for high-performance organic electronic devices including photovoltaic cells and field-effect transistors.     

Simultaneous Enhancement in Electrical Conductivity and Thermopower of n‐Type NiETT/PVDF Composite Films by Annealing

Nickel ethenetetrathiolate (NiETT) polymers are promising n‐type thermoelectric (TE) materials, but their insolubility requires the use of an inert polymer matrix to form films, which is detrimental to the TE performance. In this work, the use of thermal annealing as a post‐treatment process simultaneously enhances the electrical conductivity from 6 ± 2 to 23 ± 3 S cm^?1 and thermopower from ?28 ± 3 to ?74 ± 4 µV K^?1 for NiETT/PVDF composite films. Spectroscopic characterization reveals that the underlying mechanism involves removal of residual solvent and volatile impurities (carbonyl sulfide and water) in the NiETT polymer backbone. Additionally, microscopic characterization reveals morphological changes caused by a densification of the film that improves chain packing. These effects result in a 25 × improvement in power factor from 0.5 to 12.5 µW m^?1 K^?2 for NiETT/PVDF films and provide insight into the composition of these coordination polymers that maintain their stability under ambient conditions.