新型铜硫系薄膜太阳能电池材料制备的研究进展

薄膜太阳能电池提供了低成本、大面积的无碳发电应用前景,迅猛发展的纳米科技为高转换效率薄膜太阳能电池的低成本制造提供了新途径。新型铜硫系半导体Cu_2ZnSnS_4(CZTS)薄膜材料具有禁带宽度与太阳辐射匹配性好、光吸收系数大、元素丰度大、价格便宜、无毒等优点,因此将成为最具发展前景的薄膜太阳能电池材料。讨论与分析了CZTS薄膜和纳米晶材料的制备及由这些材料制备绿色、低成本、高效率新型太阳能电池的研究进展。     

新型铜硫系薄膜太阳能电池材料制备的研究进展

薄膜太阳能电池提供了低成本、大面积的无碳发电应用前景，迅猛发展的纳米科技为高转换效率薄膜太阳能电池的低成本制造提供了新途径。新型铜硫系半导体Cu。ZnSnS4（CZTS）薄膜材料具有禁带宽度与太阳辐射匹配性好、光吸收系数大、元素丰度大、价格便宜、无毒等优点，因此将成为最具发展前景的薄膜太阳能电池材料。讨论与分析了CZT...     

溶胶-凝胶法制备铜锌锡硫材料的研究进展

四元硫化物铜锌锡硫(CZTS)是一种新型薄膜太阳电池材料,具有锌黄锡矿结构,呈p型导电性,带隙约为1.5eV,光学吸收系数高于10~4cm~(-1),这些特性与太阳光谱相匹配。基于上述原因,CZTS薄膜是一种有望能低成本、可规模化开发利用的新型薄膜太阳电池材料。简要阐述了CZTS性质及其薄膜太阳能电池的器件结构,详细介绍了溶胶-凝胶方法制备CZTS薄膜及其相应器件效率的研究进展。最后,总结了此方法制备CZTS薄膜及其相关电池性能难以突破的关键技术问题,并提出了有效的改进措施,对CZTS薄膜太阳电池未来的研究进行了展望。     

磁控溅射制备Cu2ZnSnS4薄膜的研究进展

Cu_2ZnSnS_4(CZTS)薄膜由于其合适的禁带宽度、高的光吸收系数以及组分无毒、储量丰富等特性,被视为薄膜太阳能电池最佳的吸收层材料之一。磁控溅射是制备CZTS薄膜的主要方法之一,因为其制备过程相对简单且可以产业化,一直是太阳能电池领域的研究热点。从磁控溅射制备CZTS薄膜的3种路径出发,综述了近年来各种路径在制备CZTS薄膜方面的研究进展,比较了3种路径的优缺点,同时对磁控溅射制备CZTS薄膜的发展前景进行了展望。     

CZTS薄膜太阳能电池无镉缓冲层材料的研究进展

Cu(In,Ga) Se_2(CIGS)薄膜太阳能电池是单结转换效率最高(～22. 6%)的光伏器件,但In、Ga是稀缺元素,从而限制了CIGS电池的产业化。新型材料Cu_2ZnSnS_4(CZTS)是结构与光电性能均与CIGS十分相似的直接带隙半导体材料,它在CIGS器件结构中可替代CIGS吸收层,并得到新型CZTS薄膜太阳能电池。与CIGS相反,CZTS的原料丰富、无毒。大量研究表明,CZTS薄膜太阳能电池具有较高的转换效率和良好的稳定性,且可采用低成本、非真空的溶液法薄膜沉积技术来制造,因此CZTS器件是一种低成本、环境友好、极具产业化前景的薄膜太阳能电池。CZTS器件具有与CIGS器件一样的堆层结构{SLG/Mo/CZTS/CdS/i-ZnO/n-ZnO},目前转换效率最高(～12. 6%)的CZTS器件仍沿用CIGS器件的CdS缓冲层,因而大规模生产与应用中存在高毒重金属镉污染的危险,寻找能替代CdS的无镉缓冲层材料来消除潜在的镉污染问题十分必要。此外,与高效率的{CIGS/CdS}器件相比,{CZTS/CdS}器件界面的能带匹配可能并不是最优,CZTS器件的转换效率还远不如CIGS器件,因此需要寻找新的无镉缓冲层材料。在确定新缓冲层材料时,必须考虑{CZTS/新缓冲层}界面的能级对齐效应。CIGS和CZTS器件的缓冲层新材料基本上可归纳为3种半导体材料:硫化物、硫氧化物、氧化物。这些材料的薄膜均可用化学浴(CBD)法等多种方法来制备。材料选取很大程度上取决于其与CZTS或CIGS吸收层接触所形成界面上的导带带阶情况,因为导带带阶对器件性能参数有很大的影响。大的正导带带阶(尖刺状带阶)对少子(电子)收集存在一个势垒而降低短路电流密度J_(sc);相反,负导带带阶(断崖状带阶)导致缓冲层与吸收层界面上的复合增大而降低了开路电压V_(oc);理想情况是器件有一个小(0～0. 4 eV)的正导带带阶(尖刺状带阶),正如在使用CdS缓冲层的CIGSSe器件中所发现的那样。为了研发低成本、环境友好的CZTS电池器件的新型缓冲层材料,本文综述了CZTS和CIGS器件的无镉缓冲层材料的研究进展,讨论了无镉缓冲层材料的选用条件,以及多种硫化物(如ZnS和In_2S_3)、硫氧化物(如Zn(S,O)和In(S,O,OH))、氧化物(如ZnO、TiO_2、Zn_(1-x)Mg_xO_y和Zn_(1-x)Sn_xO_y等)薄膜作为CZTS缓冲层的性能特点(特别是它们的导带带阶)以及存在的问题,探讨了其发展方向。对于含硒CZTSSe器件,In2S3、Zn(S,O)是良好的无镉缓冲层材料,而对于更环保、低成本的全硫CZTS器件,Zn_(1-x)Mg_xO_y和Zn_(1-x)Sn_xO_y可提供良好性能的缓冲层。     

阳离子部分取代Cu2ZnSnS4的研究进展

P型半导体Cu_2ZnSnS_4(CZTS)由于具有最佳的直接带隙(1.0~1.5eV)、高的光吸收系数(超过104 cm~(-1))以及丰富、无毒的元素组成,使其成为商业化低成本太阳能电池最有希望的候选材料之一。然而,材料本身的一些缺陷制约了CZTS薄膜太阳能电池效率的提高。为了提高CZTS薄膜太阳能电池的效率,研究者们使用其他阳离子部分取代Cu、Zn或Sn来改善CZTS的缺陷。从CZTS的3种不同取代位置出发,综述了近年来各种阳离子部分取代CZTS的研究进展,同时对阳离子部分取代CZTS材料的发展前景进行了展望。     

溶胶-凝胶法制备铜锌锡硫薄膜及其太阳能电池的研究进展

原料丰富价廉的铜锌锡硫(Cu2ZnSnS4,CZTS)材料与非真空、低成本绿色溶胶-凝胶法相结合在产业化制造高性价比CZTS薄膜太阳能电池方面的应用引人关注。为了了解未来发展方向,综述了溶胶-凝胶法制备CZTS薄膜与器件的研究进展,讨论了不同溶胶-凝胶工艺途径、不同溶剂、硫化等对CZTS薄膜制备与器件特性的影响,分析了Na掺杂及硫化退火对CZTS薄膜的作用,并结合绿色制造的要求探讨了其发展趋势。     

电化学沉积法制备Cu_2ZnSnS_4薄膜电池

采用简单的两电极电化学沉积金属薄膜技术,在镀钼的钠钙玻璃衬底上共沉积Cu-Sn层后,再沉积Zn金属层,制备出Cu-Sn-Zn金属预制层。在不同的温度下进行低温退火后,以硫粉作为硫源高温硫化金属预制层,制备出晶体质量较好的Cu2ZnSnS4(CZTS)薄膜。通过X射线衍射仪(XRD)、扫描电镜(SEM)及能谱仪(EDS)对薄膜的晶体结构、表面形貌和薄膜组分进行分析表征,发现共沉积Cu-Sn层,再沉积Zn金属层得到的CZT预制层表面平整但晶粒尺寸较小,经过退火处理后晶粒尺寸得到改善,且硫化后所得到的CZTS薄膜不易从Mo衬底上脱落,粘附性较强。用其制备的CZTS薄膜太阳电池的开路电压Voc=569mV,短路电流密度Jsc=8.58mA/cm2,光电转换效率为1.40%。     

CdS薄膜的制备及其在CdTe电池中的应用

CdTe薄膜电池是发展最快、应用前景最好的一类太阳能电池。CdS层是CdTe电池的窗口层材料,其薄膜质量直接影响电池的转换效率。本文介绍了化学水浴沉积(CBD)和闭空间升华(CSS)两种方法沉积CdS薄膜,并完成单电池器件的制备和测试。CSS方法制备的薄膜结晶较大,光学和电学性能好于CBD方法制备的薄膜,太阳能电池的光电转换效率达到10.9%。CSS方法镀膜速度快,真空环境工作,有利于大规模产业化应用。     

多周期分层溅射硫化物靶制备铜锌锡硫薄膜太阳电池EI北大核心CSCD

按照ZnS/CuS/SnS/CuS的顺序分层溅射硫化锌、硫化铜和硫化亚锡三个二元硫化物靶,制备铜锌锡硫(CZTS)的预制层。在预制层总厚度不变的情况下按照上述顺序将预制层分多个周期溅射,然后在360℃对含硫预制层进行低温退火,再在硫气氛中进行高温(600℃)硫化处理,制备出CZTS薄膜。周期数为3的CZTS薄膜表面平整致密、晶粒大小均匀,禁带宽度为1.50eV。用这种薄膜制备的CZTS薄膜太阳电池性能最好,其开路电压(Voc)为623mV,短路电流密度(Jsc)为11.79mA/cm^2,光电转换效率达到2.93%。     

Preparation of Cu2ZnSnS4 thin films by sulfurization of stacked metallic layers

Stacked precursors of Cu, Sn, and Zn were fabricated on glass/Mo substrates by electron beam evaporation. Six kinds of precursors with different stacking sequences were prepared by sequential evaporation of Cu, Sn, and Zn with substrate heating. The precursors were sulfurized at temperatures of 560 °C for 2 h in an atmosphere of N₂ + sulfur vapor to fabricate Cu₂ZnSnS₄ (CZTS) thin films for solar cells. The sulfurized films exhibited X-ray diffraction peaks attributable to CZTS. Solar cells using CZTS thin films prepared from six kinds of precursors were fabricated. As a result, the solar cell using a CZTS thin film produced by sulfurization of the Mo/Zn/Cu/Sn precursor exhibited an open-circuit voltage of 478 mV, a short-circuit current of 9.78 mA/cm², a fill factor of 0.38, and a conversion efficiency of 1.79%.     

Development of CZTS-based thin film solar cells

The low cost, environmental harmless Cu₂ZnSnS₄ (CZTS)-based thin film solar cells are fabricated by using abundant materials. The CZTS film possesses promising characteristic optical properties; band-gap energy of about 1.5 eV and large absorption coefficient in the order of 10⁴ cm^− 1. All constituents of this CZTS film, which are abundant in the crust of the earth, are non-toxic. Therefore, if we can use CZTS film practically as the absorber of solar cells, we will be free from both of the resource saving problem and the environmental pollution.In our CZTS project, CZTS absorber films were prepared by two independent techniques. One is three rf sources co-sputtering followed by annealing in sulfurized atmosphere. The latest conversion efficiency of over 6.7% was achieved by this technique. The other is co-evaporation technique. CZTS films were grown on Si (100) by vacuum co-evaporation using elemental Cu, Sn, S and binary ZnS as sources. XRD patterns indicated that the polycrystalline growth was suppressed and the orientational growth was relatively induced in a film grown at higher temperatures.In this presentation, the development of CZTS-based thin film solar cells will be surveyed.     

Growth and Raman scattering characterization of Cu2ZnSnS4 thin films

In the present work we report the results of the growth, morphological and structural characterization of Cu₂ZnSnS₄ (CZTS) thin films prepared by sulfurization of DC magnetron sputtered Cu/Zn/Sn precursor layers. The adjustment of the thicknesses and the properties of the precursors were used to control the final composition of the films. Its properties were studied by SEM/EDS, XRD and Raman scattering. The influence of the sulfurization temperature on the morphology, composition and structure of the films has been studied. With the presented method we have been able to prepare CZTS thin films with the kesterite structure.     

Cu2ZnSnS4 solar cells prepared with sulphurized dc-sputtered stacked metallic precursors

In the present work we report the details of the preparation and characterization results of Cu₂ZnSnS₄ (CZTS) based solar cells. The CZTS absorber was obtained by sulphurization of dc magnetron sputtered Zn/Sn/Cu precursor layers. The morphology, composition and structure of the absorber layer were studied by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Raman scattering. The majority carrier type was identified via a hot point probe analysis. The hole density, space charge region width and band gap energy were estimated from the external quantum efficiency measurements. A MoS₂ layer that formed during the sulphurization process was also identified and analyzed in this work. The solar cells had the following structure: soda lime glass/Mo/CZTS/CdS/i-ZnO/ZnO:Al/Al grid. The best solar cell showed an open-circuit voltage of 345 mV, a short-circuit current density of 4.42 mA/cm², a fill factor of 44.29% and an efficiency of 0.68% under illumination in simulated standard test conditions: AM 1.5 and 100 mW/cm².     

Growth of Cu2SnS3 thin films by solid reaction under sulphur atmosphere

Cu₂SnS₃ thin film have been synthesized by solid state reaction under vapour sulphur pressure at 530 °C, during 6 h, via a sequentially deposited copper and tin layers Cu/Sn/Cu…Sn/Cu/Sn. The structure and the composition were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Probe Micro Analysis (EPMA). X-ray diffraction revealed that as the deposited film crystallizes in the cubic structure and the crystallites exhibit preferential 111 orientation of the grains. Moreover, EPMA analysis confirmed that the obtained film is stoichiometric. The SEM study shows the presence of spherical particles of ≈100-120 nm diameters. The optical absorption coefficient and band gap of the film were estimated by means of transmission and reflection optical measurements at room temperature. A relatively high absorption coefficient in the range of 10⁴ cm⁻¹ was indeed obtained and the band gap value is of the order of 1.1 eV. On the other hand, the electrical conductivity of Cu₂SnS₃ film prepared in the present experiment is suitable for fabricating a thin film solar cell based on not cheaper and environmental friendly material.     

Real-time investigations on the formation reactions during annealing of sulfurized Cu-Sn precursors

The quaternary compound kesterite Cu₂ZnSnS₄ (CZTS) is a promising candidate for the production of low-cost thin film solar cells.Depending on the precursor composition and deposition technique several intermetallic precursor phases may appear, affecting the formation reactions during the crystallization process of the thin film absorber. A better understanding of these formation reactions in the system Cu-Zn-Sn-S is required for the optimization of CZTS absorbers and future development of solar modules.The crystallization of CZTS is completed by the reaction of Cu₂SnS₃ and ZnS. The formation of Cu₂SnS₃ itself depends on the different available precursor compounds after sulfur evaporation. Incomplete conversion of binary sulfides during annealing may lead to the formation of undesirable compounds, i.e. the transformation of Cu₂SnS₃ into Cu₄SnS₄ via reaction with Cu_2-xS, which affect or even inhibit the crystallization of CZTS.Therefore a precise knowledge about formation reactions of binary and ternary Cu-Sn sulfides during annealing at low temperatures is important to crystallize a monophase CZTS absorber. Real-time investigations on the formation reactions in the quaternary and also the ternary subsystems of Cu-Zn-Sn-S while annealing stacked elemental layers elucidate the reaction paths of binary and ternary sulfides.We report on results of time-resolved and angle-dispersive XRD experiments during annealing comparing the formation reactions in sulfurized Cu-Sn precursors prepared by different deposition techniques.     

Cu2ZnSnS4 thin films and nanowires prepared by different single-step electrodeposition method in quaternary electrolyte

We investigated the effect of single-step electrodeposition methods for the fabrication of CZTS thin films as solar cell absorber layer. For deposition of CZTS thin films, a potentiostatic method and a pulsed potential electrodeposition method were examined. Near stoichiometric CZTS thin films were prepared by potentiostatic deposition method. On the other hands, the samples deposited by pulsed potential method showed wire-like CZTS nanostructures. The nanowires were composed of the Cu and S element mainly and included Zn and Sn microelements. From these results, we realized that the electrodeposition methods strongly affect the structural and compositional characteristics of as-deposited CZTS thin films.