Hybrid Silver Nanowire/Titanium Oxides Nanocomposites as Anode for Dye‐Sensitized Solar Cell Application

In this study, we investigated the effect of adding metallic nanowires in the anode of dye‐sensitized solar cell (DSSC) to improve the photovoltaic efficiency. Photo‐excited electrons can be efficiently transferred to the electrode through the network of the dispersed metallic nanowires added in the anode. We compared the photovoltaic performance with the anodes of standard P‐25, the silver nanowire/P‐25, and the TiO₂ coated silver nanowire/P‐25 DSSC. The DSSC with TiO₂ coated silver nanowires shows significantly improved (about 1.5 and 2.0 times) photovoltaic efficiency and structural durability compared with that of the standard P‐25 and the silver nanowires without coating DSSC. The TiO₂ coated silver nanowire can resist the redox chemical corrosions by iodide ions since they are protected from contact with electrolytes during the photovoltaic reaction by the coated thin TiO₂ layer. The presence of the metal network (silver nanowires) improves the production and transportation of light generated current so as to the photovoltaic efficiency.     

还原石墨烯-CuInS2复合材料的制备及光伏性能

利用溶剂热法制备了新型的还原石墨烯-CuInS₂(rGO-CuInS₂)复合材料. 通过X射线衍射(XRD)、 Raman光谱、 紫外-可见吸收光谱(UV-Vis)、 荧光光谱(PL)、 透射电子显微镜(TEM)及高分辨透射电子显微镜(HRTEM)等对所得材料的结构进行了表征. 结果表明, rGO-CuInS₂复合材料中CuInS₂的尺寸为3~5 nm. 将不同组成的rGO-CuInS₂复合材料应用于杂化太阳能电池, 结果发现, 与还原石墨烯(rGO)的能量转换效率相比, rGO-CuInS₂复合材料的能量转换效率得到明显提高, 通过对不同组成的rGO-CuInS₂复合材料制备的太阳能电池器件进行分析, 得到性能达到最高效率(1.10%)时复合物的最佳组成.     

Photocurrent response in a double barrier structure with quantum dots–quantum well inserted in central well

We report the photocurrent response in a double barrier structure with quantum dots–quantum well inserted in central well. When this quantum dots–quantum well hybrid heterostructure is biased beyond +1 or −1 V, the photocurrent response manifests itself as a step-like enhancement, increasing linearly with the light intensity. Most probably, at proper bias condition, the pulling down of the X minimum of GaAs at the outgoing interface of the emitter barrier by the photovoltaic effect in GaAs QW will initiate the Γ–X–X tunneling at much lower bias as compared with that in the dark. That gives rise to the observed photocurrent response.     

锰掺杂近化学计量比铌酸锂晶体的电荷输运过程

用泵浦(350 nm)-探测(780 nm)法研究了轻度锰掺杂近化学计量比铌酸锂晶体的光致吸收的特征,结果表明光致吸收的暗衰减过程以扩展指数的形式衰减,并测量了饱和光致吸收、衰减时间常量和扩展因子对泵浦光光强的依赖关系.在z轴方向上加直流电场测量了紫外光照射下光伏打电流强度和光电导,发现它们与光强之间成超线性关系.实验结果可以用考虑本征缺陷能级和掺杂能级之间激发和复合的修正的双中心电荷输运模型进行定量的解释.     

Photovoltaic activity in a ZnSe/PEO–chitosan blend electrolyte junction

Thin films of ZnSe and PEO–chitosan blend polymer doped with NH₄I and iodine crystals were prepared to form the two sides of a semiconductor electrolyte junction. ZnSe was electrodeposited on indium tin oxide (ITO) conducting glass. The polymer is a blend of 50 wt% chitosan and 50 wt% polyethylene oxide. The polymer blend was complexed with ammonium iodide (NH₄I), and some iodine crystals were added to the polymer–NH₄I solution to provide the I⁻/I³⁻redox couple. The room temperature ionic conductivity of the polymer electrolyte is 4.32 × 10⁻⁶ S/cm. The polymer film was sandwiched between the ZnSe semiconductor and an ITO glass to form a ZnSe/polymer electrolyte/ITO photovoltaic cell. The open circuit voltage (V _oc) of the fabricated cells ranges between 200 to 400 mV and the short circuit current between 7 to 10 μA.     

有偏压的光伏光折变晶体中的空间灰孤子

修正和完善了有偏压的光伏光折变晶体中空间孤子的非线性波动方程的理论.当光伏效应可忽略时,它转化为屏蔽孤子的非线性波动方程;当外电场为零时,它转化为闭路和开路光伏孤子的非线性波动方程.证明了有偏压的光伏光折变晶体中存在着空间灰孤子.它起源于对外电场的非均匀空间屏蔽和光伏效应.当光伏效应可忽略时,它转化为屏蔽灰孤子;当外电场为零闭路时,它预言了在光伏光折变晶体中存在着光伏灰孤子.     

A study of energy band gap versus temperature for Cu2ZnSnS4 thin films

The temperature dependent band gap energy of Cu₂ZnSnS₄ thin film was studied in the temperature range of 77-410 K. Various relevant parameters, which explain the temperature variation of the fundamental band gap, have been calculated using empirical and semi-empirical models. Amongst the models evaluated, the Varshni and Pässler models show the best agreement with experimental data in the middle temperature range. However, the Bose-Einstein model fits reasonably well over the entire temperature range evaluated. The calculated fitting parameters are in good agreement with the estimated value of the Debye temperature calculated using the Madelung-Einstein approximation and the Hailing method.     

Study on the photovoltaic property of Cu4SnS4 synthesized by mechanochemical process

Photovoltaic property of Cu₄SnS₄ (CTS) is studied by employing a superstrate solar cell structure of Mo/CTS/In₂S₃/TiO₂/fluorine-doped tin oxide (FTO) glass for the first time. The CTS absorber layer was prepared by a combination of mechanochemical and doctor blade processes. The annealing effects on the structural, optical and electronic properties of the CTS absorber layer were investigated. The novel CTS absorber layer shows conversion efficiency as high as 2.34% under the standard AM 1.5 condition.     

Synthesis of ZnO nanoplates decorated rhombus-shaped ZnO nanorods and their application in solar cells

Novel nanostructures of ZnF(OH) nanoplates decorated rhombus-shaped ZnF(OH) nanorods were fabricated. The obtained precursors were transformed by calcination to porous hierarchical ZnO nanostructures with the original morphologies retained. Field emission scanning electron microscope images exhibit that the nanoplates are grown in the interstices between the nanorods and on the top of the nanorods. The structure and composition of the obtained products have been confirmed by transmission electron microscope and X-ray diffraction measurements. The obtained ZnO nanostructures have been successfully used in solar cells. The light-to-electricity conversion results show that the complex nanostructures exhibit a power conversion efficiency of 1.36% with a photoelectrode thickness of 4.2 µm, which is comparable to those based on 40 µm vertically aligned hexagonal-shaped ZnO nanowire array photoelectrodes. These results indicate that the synthesized ZnO nanoplate decorated rhombus-shaped ZnO nanorod nanostructures are more suitable for application as a photoelectrode in solar cells.