CIGS薄膜太阳能电池缓冲层CdS薄膜的制备研究

目前CdS材料的制备方法有很多种,但是最常用的是化学水浴法。本文研究了浓度、反应溶液pH值、温度、沉积时间对CdS缓冲层薄膜的影响,对CIGS薄膜太阳能电池缓冲层CdS薄膜的制备方法进行了论述。     

太阳电池中CdS多晶薄膜的微结构及性能

采用化学水浴法制备了CdS多晶薄膜，通过XRD，AFM，XPS和光学透过率谱等测试手段研究了CdS多晶薄膜生长过程中的结构和性能.结果表明，随着沉积的进行，薄膜更加均匀、致密，与衬底粘附力增强，其光学能隙逐渐增大，薄膜由无定形结构向六方(002)方向优化生长，同时出现了Cd(OH)2相.在此基础上，通过建立薄膜的生长机制与性能的联系，沉积出优质CdS多晶薄膜，获得了转化效率为13.38%的CdS/CdTe小面积电池.     

CdS薄膜的可见和近红外光谱性能研究

在康宁7059玻璃衬底上采用磁控溅射、化学水浴和近空间升华法制备CdS薄膜,在FTO、ITO、AZO衬底上采用磁控溅射法制备CdS薄膜。分别对两组CdS薄膜的形貌、结构和光学性能进行了研究,结果表明:采用不同工艺和衬底条件制备的CdS薄膜具有不同的形貌和结构,并表现出不同的光学性能。对于不同的制备技术,化学水浴法制备的CdS薄膜在520～820nm范围的光谱平均透过率最高,光学带隙最大为2.418eV,磁控溅射法制备的CdS薄膜在820～1200nm和520～1200nm范围的光谱平均透过率最高。对于不同的衬底条件,在FTO衬底上磁控溅射制备的CdS薄膜在820～1200nm和520～1200nm范围的光谱平均透过率最高。     

太阳电池中CdS多晶薄膜的微结构及性能

采用化学水浴法制备了CdS多晶薄膜,通过XRD,AFM,XPS和光学透过率谱等测试手段研究了CdS多晶薄膜生长过程中的结构和性能.结果表明,随着沉积的进行,薄膜更加均匀、致密,与衬底粘附力增强,其光学能隙逐渐增大,薄膜由无定形结构向六方(002)方向优化生长,同时出现了Cd(OH)2相.在此基础上,通过建立薄膜的生长机制与性能的联系,沉积出优质CdS多晶薄膜,获得了转化效率为13.38%的CdS/CdTe小面积电池.     

CdS薄膜的制备及其性能

采用化学池沉积(CBD)法,在三种衬底(玻片、ITO玻片、SnO2玻片)上沉积CdS薄膜,并利用扫描电镜(SEM)、透射光谱、X射线衍射(XRD)和微电流高阻计等方法对沉积膜进行了测试分析,计算出CdS薄膜的能隙宽度和电导激活能,阐述了CBD法中CdS薄膜的生长沉积机制以及不同衬底对沉积效果的影响.结果表明:不同衬底的成膜效果差异较大,其中以SnO2玻片效果最佳.     

CdS薄膜的制备及其性能

采用化学池沉积(CBD)法,在三种衬底(玻片、ITO玻片、SnO2 玻片)上沉积CdS薄膜,并利用扫描电镜(SEM)、透射光谱、X射线衍射(XRD)和微电流高阻计等方法对沉积膜进行了测试分析,计算出CdS薄膜的能隙宽度和电导激活能,阐述了CBD法中CdS薄膜的生长沉积机制以及不同衬底对沉积效果的影响.结果表明:不同衬底的成膜效果差异较大,其中以SnO2 玻片效果最佳     

CdS/CdTe异质结复合薄膜的制备及其性能表征

在玻璃衬底上依次采用化学水浴法(CBD)和真空蒸发工艺沉积CdS和CdTe薄膜,并在不同条件下进行热处理,制备了CdTe/CdS异质结复合薄膜。利用XRD、SEM、AFM和UV-VIS透射光谱对薄膜的结构、表面形貌、剖面及光学性能进行了研究。结果表明:以玻璃衬底和CdS薄膜作为衬底沉积的CdTe多晶薄膜结构相似,均具有(1l1)面择优取向;不同条件下制备的薄膜致密且粒径均匀,随着热处理温度的升高,薄膜晶粒增大明显,并出现CdS层减薄的现象,但薄膜的粗糙度也随之增大;CdCl2氛围下热处理后,薄膜粒径增大,粗糙度明显降低,其(111)晶面的择优取向进一步增强,且透过率下降,这对于提高太阳电池的光谱响应是非常有利的。     

不同方法及衬底类型对CdS多晶薄膜性能的影响

采用化学水浴法和磁控溅射法分别在AZO、FTO、ITO透明导电玻璃衬底上制备了CdS薄膜,利用扫描电镜、XRD以及透射光谱等测试手段,研究了两种制备方法对不同衬底生长CdS薄膜形貌、结构和光学性能的影响.研究结果表明,不同方法制备的CdS薄膜表面形貌均依赖于衬底的类型,水浴法制备的CdS薄膜晶粒度较大,表面相对粗糙.不同方法制备的CdS薄膜均为立方相和六角相的混相结构,溅射法制备的多晶薄膜衍射峰清晰、尖锐,结晶性较好.水浴法制备的CdS薄膜透过率整体低于溅射法,但在短波处优势明显.     

Cd1-xZnxTe多晶薄膜的制备、性能与光伏应用

用共蒸发法制备了Cd1-xZnxTe多晶薄膜,薄膜结构属立方晶系空间群F43m.通过透射光谱的测量,计算光能隙,得到室温时薄膜的光能隙随组分x值的变化满足二次方关系.作为对异质结界面的修饰,提出了有Cd1-x-ZnxTe过渡层的CdS/CdTe/Cd1-xZnxTe/ZnTe∶Cu电池.并在相同工艺下制备了CdS/CdTe/Cd0.4Zn0.6Te/ZnTe∶Cu与CdS/CdTe/ZnTe∶Cu太阳电池,发现前者比后者效率平均增加了35.0%.     

CIGS薄膜太阳能电池结构分析

阐述了影响铜铟镓硒(CIGS)薄膜太阳能电池性能和效率的技术因素,包括CIGS半导体材料的晶体结构、电池的结构组成、衬底材料的选择以及CIGS薄膜的Na掺杂等。分析了多元共蒸发法、硒化法沉积CIGS吸收层以及化学水浴法沉积Cd S缓冲层的具体工艺和特征,介绍了柔性CIGS薄膜太阳能电池的卷对卷技术,最后就CIGS薄膜太阳能电池的研发与商业化生产中遇到的挑战及解决方法进行了分析与归纳。     

Research on structural characteristics of large-scale CdS thin films deposited by CBD under low ammonia condition

Cadmium sulfide (CdS) buffer layers with the scale of 10 cm×10 cm are deposited by chemical bath deposition (CBD) with different temperatures and thiourea concentrations under low ammonia condition. There are obvious hexagonal phases and cubic phases in CdS thin films under the conditions of low temperature and high thiourea concentration. The main reason is that the heterogeneous reaction is dominant for homogeneous reaction. At low temperature, CdS thin films with good uniformity and high transmittance are deposited by adjusting the thiourea concentration, and there is almost no precipitation in reaction solution. In addition, the low temperature is desired in assembly line. The transmittance and the band gap of CdS thin films are above 80% and about 2.4 eV, respectively. These films are suitable for the buffer layers of large-scale Cu(In,Ga)Se2 (CIGS) solar cells.     

High Performance PbS Colloidal Quantum Dot Solar Cells by Employing Solution‐Processed CdS Thin Films from a Single‐Source Precursor as the Electron Transport Layer

CdS thin films are a promising electron transport layer in PbS colloidal quantum dot (CQD) photovoltaic devices. Some traditional deposition techniques, such as chemical bath deposition and RF (radio frequency) magnetron sputtering, have been employed to fabricate CdS films and CdS/PbS CQD heterojunction photovoltaic devices. However, their power conversion efficiencies (PCEs) are moderate compared with ZnO/PbS and TiO₂/PbS heterojunction CQD solar cells. Here, efficiencies have been improved substantially by employing solution‐processed CdS thin films from a single‐source precursor. The CdS film is deposited by a straightforward spin‐coating and annealing process, which is a simple, low‐cost, and high‐material‐usage fabrication process compared to chemical bath deposition and RF magnetron sputtering. The best CdS/PbS CQD heterojunction solar cell is fabricated using an optimized deposition and air‐annealing process achieved over 8% PCE, demonstrating the great potential of CdS thin films fabricated by the single‐source precursor for PbS CQDs solar cells.     

Cu(In,Ga)Se2太阳电池缓冲层ZnS薄膜性质及应用

在含有ZnSO4,SC(NH2)2,NH4OH的水溶液中采用CBD法沉积ZnS薄膜,XRF和热处理前后的XRD测试表明,ZnS沉积薄膜为立方相结构,薄膜含有非晶态的Zn(OH)2.光学透射谱测试表明,制备的薄膜透过率(λ＞500nm)约为90%,薄膜的禁带宽度约为3.51eV.ZnS薄膜沉积时间对Cu(In,Ga)Se2太阳电池影响显著,当薄膜沉积时间在25～35min时,电池的综合性能最好.对比了不同缓冲层的电池性能,采用CBD-CdS为缓冲层的电池转换效率、填充因子、开路电压稍高于CBD-ZnS为缓冲层的无镉电池,但无镉电池的短路电流密度高于前者,两者转换效率相差2%左右.ZnS可以作为CIGS电池的缓冲层,替代CdS,实现电池的无镉化.     

The effect of oxygen on interface microstructure evolution in CdS/CdTe solar cells

Microstructural changes at the CdS/CdTe solar cell interface where close‐spaced sublimation (CSS) is used as the growth technique to deposit the p‐type CdTe absorber layer are studied by systematic layer characterization at various stages during heterojunction growth. CdS layers grown by both chemical bath deposition (CBD) and CSS provide a basis for determining the effects of CdS crystallinity, grain size, and oxygen content on the subsequent CdTe layer. As‐grown CBD CdS films exhibit small grains and variations in optical properties attributed to film impurities. In contrast, CSS yields CdS films with good crystallinity, larger grains, and nearly ideal optical properties. The hexagonal nature of CSS‐grown CdS is seen to nucleate hexagonal CdTe during the initial stages of CdTe film growth. Cubic CdS deposited by CBD in contrast promotes cubic CdTe nucleation. Oxygen anneals in the latter case can aid hexagonal CdTe nucleation. Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) of the CdS/CdTe interface show CdS‐dependent differences in interdiffusion at the interface. This interdiffusion appears to be determined by the oxygen level in the CdS. When low‐oxygen‐containing CSS CdS films are used, sulfur diffusion is substantial, leading to significant consumption of the CdS layer. When these same films are annealed in oxygen, the consumption is reduced. Te diffusion into the CdS layer is also observed to decrease with oxygen anneals. Optical modeling shows that Te alloying with the CdS layer can greatly reduce the short‐circuit current of CdS/CdTe devices. Copyright © 2002 John Wiley & Sons, Ltd.     

Zn1?xMgxO用于 CIGS 太阳电池的研究进展

Zn1-xMgxO透过率高、带隙可调,且与CIGS太阳电池在晶格和能带结构上匹配良好,可用作CIGS太阳电池缓冲层、窗口层,因此制备高质量的Zn1-xMgxO薄膜是提高太阳电池性能的关键。文章介绍了Zn1-xMgxO薄膜的结构特性、光学特性及制备方法;从Mg含量、Zn1-xMgxO膜厚及Zn1-xMgxO/CIGS界面处缺陷密度等方面概述了Zn1-xMgxO用于CIGS太阳电池的研究进展,并比较了Zn1-xMgxO与In2S3,ZnS,CdS等其他材料作缓冲层的CIGS太阳电池性能的差别。     

A comparative study of Cd‐ and Zn‐compound buffer layers on Cu(In1−x,Gax)(Sy,Se1−y)2 thin film solar cells

This paper reports a comparative study of Cu(In,Ga)(S,Se)₂ (CIGSSe) thin‐film solar cells with CBD‐CdS, CBD‐ZnS(O,OH) and ALD‐Zn(O,S) buffer layers. Each buffer layer was deposited on CIGSSe absorber layers which were prepared by sulfurization after selenization (SAS) process by Solar Frontier K. K. Cell efficiencies of CBD‐CdS/CIGSSe, CBD‐ZnS(O,OH)/CIGSSe and ALD‐Zn(O,S)/CIGSSe solar cells exceeded 18%, for a cell area of 0.5 cm². The solar cells underwent a heat‐light soaking (HLS) post‐treatment at 170 °C under one‐sun illumination in the air; among the three condtions, the ALD‐Zn(O,S)/CIGSSe solar cells showed the highest cell efficiency of 19.78% with the highest open‐circuit voltage of 0.718 V. Admittance spectroscopy measurements showed a shift of the N₁ defect's energy position toward shallower energy positions for ALD‐Zn(O,S)/CIGSSe solar cells after HLS post‐treatment, which is in good agreement with their higher open‐circuit voltage and smaller interface recombination than that of CBD‐ZnS(O,OH)/CIGSSe solar cells. Copyright © 2015 John Wiley & Sons, Ltd.     

Cadmium sulfide thin films growth by chemical bath deposition

Cadmium sulfide (CdS) thin films have been prepared by a simple technique such as chemical bath deposition (CBD).A set of samples CdS were deposited on glass substrates by varying the bath temperature from 55 to 75 ℃ at fixed deposition time (25 min) in order to investigate the effect of deposition temperature on CdS films physical properties.The determination of growth activation energy suggests that at low temperature CdS film growth is governed by the release of Cd2+ ions in the solution.The structural characterization indicated that the CdS films structure is cubic or hexagonal with preferential orientation along the direction (111) or (002),respectively.The optical characterization indicated that the films have a fairly high transparency,which varies between 55％ and 80％ in the visible range of the optical spectrum,the refractive index varies from 1.85 to 2.5 and the optical gap value of which can reach 2.2 eV.It can be suggested that these properties make these films perfectly suitable for their use as window film in thin films based solar cells.     

High-Efficiency Polycrystalline CdS/CdTe Solar Cells on Buffered Commercial TCO-Coated Glass

Multiple polycrystalline CdS/CdTe solar cells with efficiencies greater than 15% were produced on buffered, commercially available Pilkington TEC Glass at EPIR Technologies, Inc. (EPIR, Bolingbrook, IL) and verified by the National Renewable Energy Laboratory (NREL). n-CdS and p-CdTe were grown by chemical bath deposition (CBD) and close space sublimation, respectively. Samples with sputter-deposited CdS were also investigated. Initial results indicate that this is a viable dry-process alternative to CBD for production-scale processing. Published results for polycrystalline CdS/CdTe solar cells with high efficiencies are typically based on cells using research-grade transparent conducting oxides (TCOs) requiring high-temperature processing inconducive to low-cost manufacturing. EPIR’s results for cells on commercial glass were obtained by implementing a high-resistivity SnO₂ buffer layer and by optimizing the CdS window layer thickness. The high-resistivity buffer layer prevents the formation of CdTe-TCO junctions, thereby maintaining a high open-circuit voltage and fill factor, whereas using a thin CdS layer reduces absorption losses and improves the short-circuit current density. EPIR’s best device demonstrated an NREL-verified efficiency of 15.3%. The mean efficiency of hundreds of cells produced with a buffer layer between December 2010 and June 2011 is 14.4%. Quantum efficiency results are presented to demonstrate EPIR’s progress toward NREL’s best-published results.     

Role of the CdS buffer layer as an active optical element in Cu(In,Ga)Se2 thin‐film solar cells

ZnO/CdS/Cu(In,Ga)Se₂ (CIGS) thin‐film heterojunction solar cells with CdS buffer layers of thicknesses between 0 and 85 nm are characterized by current–voltage, quantum efficiency, and optical reflection measurements. We investigate the correlation between the short‐circuit current density and the CdS layer thickness, focusing on the counteracting effects of light absorption and reduced optical reflection induced by the CdS layer. Both effects almost compensate each other for CdS layer thicknesses between 0 and 40 nm. Thus, an optimization of the short‐circuit current density is not achieved by omitting the CdS layer, but rather by replacing the CdS buffer with an alternative buffer material with higher bandgap energy and optical constants similar to those of CdS. Copyright © 2002 John Wiley & Sons, Ltd.