CdS/CdTe叠层太阳电池的制备及其性能

CdS/CdTe太阳电池是薄膜太阳电池研究工作的一个重要方向.为了提高开路电压Voc、改善电池的光谱响应,进而提高电池的转换效率,在此提出CdS/CdTe叠层太阳电池结构.文中,叠层电池的顶电池由CdS/CdTe超薄层构成;底电池由CdS/CdTe薄膜层构成.经分析测试,实验制备的CdS/CdTe叠层太阳电池具有明显的叠层结构,开路电压最高达到了852mV,短路电流密度最大为13mA/cm2,填充因子最高为55.2%,这种叠层电池的效率达到了8.16%(0.071cm2).研究表明相对于传统的单层CdS/CdTe太阳电池,CdS/CdTe叠层电池的制备对研究如何提高CdS/CdTe太阳电池的光伏性能有一定的参考价值.     

硫化镉纳米膜的电化学制备方法

采用电沉积方法在表面活性剂和电解液的界面制备了硫化镉纳米膜.通过对不同电解液体系和表面活性剂体系中纳米硫化镉膜沉积情况进行比较发现,相同条件下采用硫代乙酰胺体系为电解液,蓖麻油类为表面活性剂可以在液/液界面制备硫化镉纳米膜.考察了表面活性剂种类、电解液浓度和温度及溶液的pH值对制备硫化镉纳米膜的影响,确立了制备纳米膜的最佳工艺条件:氯化镉浓度为4 mmol·L-1,硫代乙酰胺浓度为12 mmol·L-1,槽压5 V,pH值为4.8,蓖麻油/十六醇的用量为0.06 ml·cm-2.实验表明,最佳工艺条件下制备的硫化镉纳米膜晶粒粒径均匀、平均粒径在30 nm左右,近似球形,将在非线性光学材料领域有特殊的应用前景.     

热处理工艺对CdS微晶掺杂玻璃析晶和二阶非线性光学性能的影响

采用高温熔融法和后期热处理工艺制备了CdS微晶掺杂玻璃.结构分析表明,620 ℃/10 h热处理后CdS微晶颗粒尺寸分布均匀、晶粒发育较好.样品极化前后都观察到了明显的SHG,极化后样品的SH强度有了极大的提高.微晶的尺寸分布和表面状态极大地影响了样品极化前后的SH强度.     

Hydrophilic bismuth sulfur nanoflower superstructures with an improved photothermal efficiency for ablation of cancer cells

Nanomaterials with intense near-infrared (NIR) absorption exhibit effective photon-to-thermal energy transfer capabilities and can generate heat to ablate cancer cells, thus playing a pivotal role in photothermal cancer therapeutics. Herein, hydrophilic flower-like bismuth sulfur (Bi₂S₃) superstructures with uniform size and improved NIR absorption were controllably synthesized via a facile solvothermal procedure assisted by polyvinylpyrrolidone (PVP), which could adjust the product morphology. Induced by an 808-nm laser, the as-prepared Bi₂S₃ nanoflowers exhibited much higher photothermal conversion efficiency (64.3%) than that of Bi₂S₃ nanobelts (36.5%) prepared in the absence of PVP. This can be attributed not only to the Bi₂S₃ nanoflower superstructures assembled by 3-dimensional crumpled-paper-like nanosheets serving as many laser-cavity mirrors with improved reflectivity and absorption of NIR light but also to the amorphous structures with a lower band gap. Thus, to achieve the same temperature increase, the concentration or laser power density could be greatly reduced when using Bi₂S₃ nanoflowers compared to when using Bi₂S₃ nanobelts, which makes them more favorable for use in therapy due to decreased toxicity. Furthermore, these Bi₂S₃ nanoflowers effectively achieved photothermal ablation of cancer cells in vitro and in vivo. These results not only supported the Bi₂S₃ nanoflowers as a promising photothermal agent for cancer therapy but also paved an approach to exploit new agents with improved photothermal efficiency.

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CdS/石墨烯纳米复合材料研究进展

CdS/石墨烯纳米复合材料是一种重要的半导体光催化剂,在可见光下具有很好的催化活性。本文重点介绍了CdS/石墨烯纳米复合材料的制备方法及性能影响因素,并分析了几种常用制备方法的特点及运用效果。本文还介绍了CdS/石墨烯纳米复合材料近年来的应用研究,并对其应用的发展趋势做出了展望。     

Synthesis and photochemical performance of morphology-controlled CdS photocatalysts for hydrogen evolution under visible light

Novel CdS nanomaterials were synthesized by a simple “one-pot” hydrothermal biomolecule-assisted method using glutathione (GSH) as the sulfur source and structure-directing reagent. Various morphologies of CdS photocatalysts, such as solid nanospheres (s-CdS), hollow nanospheres (h-CdS) and nanorods (r-CdS), were obtained by controlling only the hydrothermal temperatures. The X-ray diffraction patterns confirmed that all of the samples were typical hexagonal wurtzite CdS. It was found that the absorption edge of s-CdS was at 465 nm with a greater blue shift compared to that of h-CdS and r-CdS. The photocatalytic activity of s-CdS was superior to that of h-CdS and r-CdS under visible light. Photoluminescence measurements revealed their different photogenerated electron/hole recombination ability, which was in accordance with the order of s-CdS < h-CdS < r-CdS. The excellent photocatalytic activity of s-CdS was ascribed to the small sizes of sub-nanocrystallites, which make it easy for photoinduced electrons and holes on the solid sphere to migrate to the surface and react with water and the sacrificial agent quickly. It was crucial to control the temperature for preparing CdS photocatalysts via hydrothermal methods. The formation mechanism of different morphology might be due to complexation, S-C bond rupture, spherical aggregation and Ostwald ripening processes.     

Optical properties of CdSxTe1−x polycrystalline thin films

Thin films of CdS_xTe_1−x (0≤x≤ 1) have been prepared by vacuum evaporation from solid solutions. Rutherford backscattering spectrometry has been used to determine the thickness of the films, which is in the range 8–50 nm, and x-ray diffraction analysis has been used to determine the phase. The refractive index and extinction coefficient of the films has been calculated from reflectance and transmittance measurements for the wavelength region 250–3200 nm. Polynomial functions are given for each sample, which describe the variation in refractive index and extinction coefficient over the entire wavelength range. Least squares fitting to the absorption spectra revealed that the films all have a direct band gap, although photon energies required for indirect transitions have also been found. CdS_0.8Te_0.2 is found to have the lowest absorption coefficient at energies greater than 2.1 eV.     

XPS analysis of CdS/CuInSe2 heterojunctions

CdS/CuInSe₂ (CIS) heterojunctions were investigated by XPS analysis. An In-excess layer which may form an ordered vacancy compound (OVC) was present at the as-deposited CIS surface and it remained after chemical bath deposition of a CdS layer. The In-excess layer was removed by preferential etching with NH₃ aqueous solution. This result implies that the surface of the as-deposited CIS film was converted from the OVC with n-type conductivity into the CIS with p-type by NH₃ treatment. The conduction band offsets at the CdS/p-CIS and CdS/n-OVC were determined to be 1.0 and 0.3 eV, respectively. The CIS solar cells fabricated with n-OVC surface layer exhibited higher cell efficiencies than those fabricated with p-CIS surface layer.     

Fabrication of vacuum-evaporated SnS/CdS heterojunction for PV applications

SnS/CdS heterojunction is a promising system for the fabrication of thin film solar cells. In our work, thin film SnS/CdS heterojunction was prepared by evaporating CdS and SnS films. The photovoltaic properties of the heterojunction were investigated with posttreatment of the window material treatment by CdCl₂ for grain size enlargement. I–V characteristics in dark and at light were taken and figures of merit were evaluated. The efficiency with and without window layer treatment were about 0.08% and 0.05%, respectively, under 100 mW/cm² intensity. To the best of our knowledge so far there has been no report on vacuum-evaporated SnS-based heterojunction with window material treatment by CdCl₂.     

CdS量子点/CdTe纳米棒光电极制备及其光电性能研究

本文利用化学沉积法和射频溅射法成功实现了CdS量子点/CdTe纳米棒复合光电极的制备。通过X射线粉末衍射(XRD)、扫描电镜(SEM)、紫外-可见吸收光谱(UV-vis)和电化学工作站分别对获得的光电极进行了结构、形貌和光电性能的表征;结果表明,所获得的光电极由CdS量子点和CdTe一维纳米棒组成,其中CdTe纳米棒沿着(111)择优方向定向生长。在不同CdS量子点厚度的光电极的电化学表征结果中,我们发现了由CdS的压电效应引起的新颖的热释电现象,并在25 cycle CdS QDs的光电极测试中获得了最好的结果,开路电压为0.49 V,短路电流为71.09 μA,其I-t曲线的开光比为6。我们在研究过程中还发现了热释电引起的电流反向现象,这一特性对于未来提高光电器件的性能具有重要的意义。