Cu2ZnSnS4薄膜光电性能及其太阳电池的制备和研究

采用硫化Zn/Sn/Cu金属多层膜的方法制备了太阳电池吸收层用的Cu2ZnSnS4(CZTS)薄膜。用X射线衍射仪、拉曼光谱仪、紫外-可见近红外分光光度计、扫描电镜、能谱仪及数字源表等对薄膜进行了一系列的表征。结果表明制备的CZTS薄膜没有杂相存在并具有标准拉曼峰。薄膜在可见光范围内的吸收系数>104cm-1,同时其光学带隙接近1.5eV。CZTS薄膜具有均匀致密的表面形貌,薄膜元素比例非常接近标准化学计量比。此外,CZTS薄膜呈现显著的光电流响应性能,其光电流的激发和衰减时间分别为0.0736和0.2646s。     

铜铟镓硒薄膜太阳能电池的发展现状以及应用前景

首先介绍了铜铟镓硒薄膜太阳能电池结构、性能特点以及目前在研究和生产过程中电池的制备方法和工艺;着重阐述了工业发达国家以及相应大公司在铜铟镓硒薄膜太阳能电池方面最新进展以及发展趋势,特别介绍了一些太阳能电池的实验室样品和组件的最高光电转化效率.也对国内在此方面的研究做了简要介绍.文中最后探讨了我国发展铜铟镓硒太阳能电池的可行性和产业化前景.     

Texture optimization process of ZnO:Al thin films using NH4Cl aqueous solution for applications as antireflective coating in thin film solar cells

ZnO:Al thin films varying the thickness from 80 to 110 nm were deposited on polished float zone < 100 > Si wafers by radio frequency magnetron sputtering at 100 °C. To texturize these surfaces with the aim of being used as antireflective coating, a wet etching process based on NH₄Cl was applied. Taking into account that the layer thickness was small, the control of the etch parameters such as etchant concentration and etching time was evaluated as a function of the textured film properties. An appropriate control of the etching rate to adjust the final thickness to the 80 nm required for the application was realized. Using NH₄Cl concentrations of 10 wt.% and short times of up to 25 s, an increase of the film roughness up to a factor of 5.6 of the as-deposited films was achieved. These optimized textured films showed weighted reflectance values below 15% and considerable better electrical properties than the as-deposited 80 nm-thick ZnO:Al films.     

Influence of growth temperature of transparent conducting oxide layer on Cu(In,Ga)Se2 thin-film solar cells

We have studied the influence of growth temperature (T_G) in the deposition of an indium tin oxide (ITO) transparent conducting oxide layer on Cu(In,Ga)Se₂ (CIGS) thin-film solar cells. The ITO films were deposited on i-ZnO/glass and i-ZnO/CdS/CIGS/Mo/glass substrates using radio-frequency magnetron sputtering at various T_G up to 350 °C. Both the resistivity of ITO and the interface quality of CdS/CIGS strongly depend on T_G. For a T_G ≤ 200 °C, a reduction in the series resistance enhanced the solar cell performance, while the p-n interface of the device was found to become deteriorated severely at T_G > 200 °C. CIGS solar cells with ITO deposited at T_G = 200 °C showed the best performance in terms of efficiency.     

Transfer of CuInS2 thin film by lift-off process and application to superstrate-type thin-film solar cells

Transfer of a CuInS₂ thin film grown on a Mo/soda-lime glass substrate was investigated using a lift-off process. The CuInS₂ thin film was flatly exfoliated, with preferential peeling occurring in the CuInS₂/MoS₂ interface vicinity. This suggests that the interfacial MoS₂ layer behaves as a sacrificial layer. The lift-off process was also applied to solar cell fabrication. A superstrate-type CuInS₂ thin-film solar cell was fabricated and exhibited no significant degradation of conversion efficiency compared with a substrate-type CuInS₂ thin-film solar cell. The lift-off process could therefore also be applied to fabricate the upper part of a tandem solar cell structure.     

Initial growth of SnO2 thin film on the glass substrate deposited by the spray pyrolysis technique

Spray pyrolysis of di-n-butyltin(IV) diacetate (DBTDA) has led to the deposition of [200]-oriented SnO₂ film on a glass substrate. In order to clarify growth mechanism of the preferential orientation the sprayed SnO₂ thin film has been investigated by using the atomic force microscopy and the X-ray photoelectron spectroscopy. The results have suggested that the sprayed solution forms the SnO₂ small particles on the glass substrate and they spread overall relatively soon. At the very early stage each particle grows with almost the same rate and only its density increases with no change in a surface roughness.     

Influence of gas flow during vacuum cold spraying of nano-porous TiO2 film by using strengthened nanostructured powder on performance of dye-sensitized solar cell

Nano-porous TiO₂ films, which can be applied to the flexible dye-sensitized solar cell (DSC), were deposited by vacuum cold spraying at room temperature with the strengthened nanostructured TiO₂ powder as feedstock. The spraying was conducted under different accelerating gas flows resulting in various particle velocities. Results show that the short-circuit photocurrent density of the cell (N719 dye) increases from 8.3 to 9.8 mA/cm² with the increase in gas flow from 3 to 7.5 L/min. A maximum overall energy conversion efficiency of 4.2% was obtained for the DSC with the TiO₂ film deposited at the gas flow of 7.5 L/min. The influence of particle velocity on the electron transport parameters and cell performance was discussed to reveal the important role of particle velocity in the formation of particle connection through high impact pressure during vacuum cold spraying.     

Structural study and electronic band structure investigations of the solid solution NaxCu1 − xIn5S8 and its impact on the Cu(In,Ga)Se2/In2S3 interface of solar cells

The present work reports investigations on the new In₂S₃ containing Cu and/or Na compounds, which are expected to be formed at the Cu(In,Ga)Se₂/In₂S₃ interface. The knowledge of these materials properties is very important in order to better understand the operation of the devices based on these junction partners.It has been observed that a solid solution Na_xCu_1 − xIn₅S₈ exists from CuIn₅S₈ (x = 0) to NaIn₅S₈ (x = 1) with a spinel-like structure. The single crystal structure determination shows that indium, copper and sodium atoms are statistically distributed on the tetrahedral sites.XPS investigations on the CuIn₅S₈, Na_0.5Cu_0.5In₅S₈ and NaIn₅S₈ compounds combined with the band gap changes reported in a previous work show that these variations are mainly due to valence band maximum shift; it is moved downward when x increases from 0 to 1. These observations are confirmed by the electron structure calculations based on the density functional theory, which additionally demonstrate that the pure sodium compound has direct gap whereas the copper-containing compounds have indirect gaps.     

Influence of precursor stacking on the absorber growth in Cu(In,Ga)S2 based solar cells prepared by a rapid thermal process

Rapid thermal sulfurization of metallic precursors has proven to be a successful method for the preparation of Cu(In,Ga)S₂ based solar cells. However, during the sulfurization, several problems can be encountered. Due to the difference in reaction rates between ternary sulfides, the process can result in absorbers with a layered CuInS₂/CuGaS₂ structure or slow and incomplete sulfurization that leads to samples where an unreacted Cu-Ga metallic phase remains at the back of the sample. The formation kinetics of single phase Cu(In,Ga)S₂ is a complex process which depends on several parameters. In this work, we focus on the influence of precursor stacking and investigate the growth of Cu(In,Ga)S₂ thin films using scanning electron microscopy and X-ray diffraction. It is observed that precursor alloying occurs prior to sulfurization and that the Cu(In,Ga)S₂ compound is formed by the interdiffusion of the ternary CuInS₂ and CuGaS₂ phases. Correlation between the structural properties of the precursors/absorbers and the obtained solar cells is made.