Quantum dot containing nanocomposite thin films for photoluminescent solar concentrators

Silicon oxide films containing CdS quantum dots have been deposited on glass substrates by a sol–gel dip-coating process. Hereby the CdS nanocrystals are grown during the thermal annealing step following the dip-coating procedure. Total hemispherical transmittance and reflectance measurements were carried out by means of a spectrophotometer coupled to an integrating sphere. For CdS-rich films, an absorption edge at photon energies in the vicinity of the band gap value of bulk CdS is observed. For lower CdS concentrations, the absorption edge shifts to higher photon energies, as expected for increasing quantum confinement. The samples show visible photoluminescence which is concentrated by total internal reflection and emitted at the edges of the substrate. The edge emission has been characterized by angle-dependent photoluminescent (PL) spectroscopy. Information on the lateral energy transport within the sample can be extracted from spectra obtained under spatial variation of the spot of excitation. The color of the photoluminescence can be tuned by varying the annealing temperature which governs crystal growth and thus the cluster size distribution. The characteristic features observed in the PL spectra clearly exhibit a blueshift for lower annealing temperatures, confirming the presence of quantum size effects.Advantages of the proposed concept of quantum dot containing coatings on glass panes for photoluminescent solar concentrators are the high potential for low-cost fabrication on the large scale and the suitability for architectural integration.     

Improvement in the efficiency of Cu-doped CdS/non-doped CdS photovoltaic cells fabricated by an all-vacuum process

Thin-film photovoltaic cells composed of p-type Cu-doped CdS (CdS(Cu)) and n-type CdS layers (CdS(Cu)/CdS system) were fabricated by an all-vacuum deposition process. The cells showed a higher response in the longer-wavelength side than at the absorption edge of CdS with an increase in the thickness of the CdS(Cu) layer. High efficiency (over 8.5%) was obtained by improvement in CdS(Cu) layer fabrication. It is thought that the photovoltic effect of the cells is caused by a p-CdS(Cu)/n-CdS homojunction.     

CdS多晶薄膜的电学性质

用化学池沉积方法（ＣＢＤ）制备了ＣｄＳ多晶薄膜，并对薄膜进行了退火处理，测量了不同ＣｄＳ薄膜光电导、暗电导和电导－温度关系，计算了电导激光活能。结果表明：刚沉积的ＣｄＳ暗电导率为１０＾－６Ω＾－１．ｃｍ＾－１比光电导率低二个数量级，退火后，电导升高，电导激活能减小。Ｘ射线衍射分析表明，经退火后，ＣｄＳ薄膜发生相变，由立方结构变成六方结构。对上述结果进行了讨论。     

CdS／CuInSe2多晶异质结太阳电池的光电流和转换效率的计算和分析

用Ｒｏｔｈｗａｒｆ的晶界复合损失模型对ＣｄＳ／ＣｕＩｎＳｅ２多晶异质结太阳电池的光电流和转换效率进行了计算，并在计算中考虑到异质结内表面复合因子Ｇ和势垒区宽度随电压的变化因素，结果发现Ｐ区受主浓度ＮＡ有一个最佳值。将我们的计算结果和Ｌ．Ｌ．Ｋａｚｍｅｒｓｋｉ等人的实验结果对照，两者基本一致。     

DMF—硫脲体系制备CdS微晶掺杂的SiO2玻璃薄膜

将镉盐和硫脲的DMF溶液加入由硅酸乙酯水解而得的SiO_2溶胶,搅拌混匀,再将基片浸入其中挂膜,经烧结即可得CdS微晶掺杂的SiO_2玻璃薄膜。吸收光谱和透射电镜表明,这样制备的一层薄膜中CdS微晶具有量子尺寸效应,荧光光谱也为这种可能性提供了佐证。由X射线衍射结果还可知CdS晶粒呈六角形。     

Eosin-G and ethyl eosin dye sensitized CdS nanowires towards dye sensitized solar cells applications

One dimensional (1-D) CdS nanowires have been grown through a low temperature chemical route and have been sensitized with eosin-G and ethyl eosin dyes to broaden the absorption spectrum of CdS and to enhance the photoelectrochemical (PEC) performance under illumination. The used method is advantageous due to its simplicity, low cost, scalability, and controllability. Interestingly, eosin-G and ethyl eosin dyes yield nearly four- and six-fold increase in device efficiency compared to bare CdS when tested in dye-sensitized solar cell assembly. Structural, surface morphological, optical, and surface wettability studies have been formulated for CdS, whereas identification of materials along with PEC investigations were conducted through current density–voltage (J-V), external quantum efficiency (EQE), characteristics under the illumination of 94.6 mW/cm² (AM 1.5G), and electrochemical impedance spectroscopy (EIS).     

Ordered Mesostructured CdS Nanowire Arrays with Rectifying Properties

Highly ordered mesoporous CdS nanowire arrays were synthesized by using mesoporous silica as hard template and cadmium xanthate (CdR₂) as a single precursor. Upon etching silica, mesoporous CdS nanowire arrays were produced with a yield as high as 93 wt%. The nanowire arrays were characterized by XRD, N₂ adsorption, TEM, and SEM. The results show that the CdS products replicated from the mesoporous silica SBA-15 hard template possess highly ordered hexagonal mesostructure and fiber-like morphology, analogous to the mother template. The current–voltage characteristics of CdS nanoarrays are strongly nonlinear and asymmetrical, showing rectifying diode-like behavior.     

Trioctylphosphine as Both Solvent and Stabilizer to Synthesize CdS Nanorods

High quality CdS nanorods are synthesized reproducibly with cadmium acetate and sulfur as precursors in trioctylphosphine solution. The morphology, crystalline form and phase composition of CdS nanorods are characterized by transmission electron microscopy (TEM), high-resolution TEM and X-ray diffraction (XRD). CdS nanorods obtained are uniform with an aspect ratio of about 5:1 and in a wurtzite structure. The influence of reaction conditions on the growth of CdS nanorods demonstrates that low precursor concentration and high reaction temperature (260 °C) are favorable for the formation of uniform CdS nanorods with 85.3% of product yield.     

有机-无机复合CdS纳米晶的制备及表征

本文采用液液两相法,在甲苯、甲醇和水两相体系中制备了烷基硫醇和芳杂环硫醇修饰的有机-无机复合的CdS半导体纳米晶.通过紫外可见吸收光谱、X-射线光电子能谱、X-射线粉末衍射、透射电子显微镜、元素分析和热重分析检测手段对样品的结构和组成进行了表征.结果表明:该方法所制备的硫化镉纳米晶是由无机纳米核及通过化学键吸附在其表面的硫醇分子所组成.纳米晶的平均粒径约为5nm,尺寸均匀,稳定性高,在空气中可长时间保存.