scholarly journals Degradation Mechanism Due to Water Ingress Effect on the Top Contact of Cu(In,Ga)Se2 Solar Cells

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4545
Author(s):  
Deewakar Poudel ◽  
Shankar Karki ◽  
Benjamin Belfore ◽  
Grace Rajan ◽  
Sushma Swaraj Atluri ◽  
...  
Keyword(s):  
Solar Cells ◽  
Indium Tin Oxide ◽  
Degradation Mechanism ◽  
Transparent Conductive Oxide ◽  
Window Layer ◽  
Copper Indium Gallium Diselenide ◽  
Copper Indium ◽  
Cigs Solar Cells ◽  
The Impact ◽  
Secondary Ion

The impact of moisture ingress on the surface of copper indium gallium diselenide (CIGS) solar cells was studied. While industry-scale modules are encapsulated in specialized polymers and glass, over time, the glass can break and the encapsulant can degrade. During such conditions, water can potentially degrade the interior layers and decrease performance. The first layer the water will come in contact with is the transparent conductive oxide (TCO) layer. To simulate the impact of this moisture ingress, complete devices were immersed in deionized water. To identify the potential sources of degradation, a common window layer for CIGS devices—a bilayer of intrinsic zinc oxide (i-ZnO) and conductive indium tin oxide (ITO)—was deposited. The thin films were then analyzed both pre and post water soaking. To determine the extent of ingress, dynamic secondary ion mass spectroscopy (SIMS) was performed on completed devices to analyze impurity diffusion (predominantly sodium and potassium) in the devices. The results were compared to device measurements, and indicated a degradation of device efficiency (mostly fill factor, contrary to previous studies), potentially due to a modification of the alkali profile.

scholarly journals Improving Performance of CIGS Solar Cells by Annealing ITO Thin Films Electrodes

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Chuan Lung Chuang ◽  
Ming Wei Chang ◽  
Nien Po Chen ◽  
Chung Chiang Pan ◽  
Chung Ping Liu
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Solar Cells ◽  
Indium Tin Oxide ◽  
Copper Indium Gallium Diselenide ◽  
Glass Substrates ◽  
Ito Film ◽  
Ito Thin Films ◽  
Cigs Solar Cells ◽  
Ito Films

Indium tin oxide (ITO) thin films were grown on glass substrates by direct current (DC) reactive magnetron sputtering at room temperature. Annealing at the optimal temperature can considerably improve the composition, structure, optical properties, and electrical properties of the ITO film. An ITO sample with a favorable crystalline structure was obtained by annealing in fixed oxygen/argon ratio of 0.03 at 400°C for 30 min. The carrier concentration, mobility, resistivity, band gap, transmission in the visible-light region, and transmission in the near-IR regions of the ITO sample were-1.6E+20 cm−3,2.7E+01 cm2/Vs,1.4E-03 Ohm-cm, 3.2 eV, 89.1%, and 94.7%, respectively. Thus, annealing improved the average transmissions (400–1200 nm) of the ITO film by 16.36%. Moreover, annealing a copper-indium-gallium-diselenide (CIGS) solar cell at 400°C for 30 min in air improved its efficiency by 18.75%. The characteristics of annealing ITO films importantly affect the structural, morphological, electrical, and optical properties of ITO films that are used in solar cells.

Effects of Mg Content on Zn1-xMgxO:Al Transparent Conducting Films

2008 ◽  
Vol 1101 ◽  
Author(s):  
Xiaonan Li ◽  
Hannah Ray ◽  
Craig L. Perkins ◽  
Rommel Noufi
Keyword(s):  
Solar Cells ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Optical Bandgap ◽  
Zno Films ◽  
Copper Indium Gallium Diselenide ◽  
Conduction Band Offset ◽  
Cigs Solar Cells ◽  
Photovoltaic Solar Cells ◽  
Mg Content

AbstractConductive zinc oxide (ZnO) films are used extensively as transparent electrodes in thin-film photovoltaic solar cells. Compared with the widely used indium tin oxide (ITO) and tin oxide (SnO2), ZnO has a smaller optical bandgap. ZnO is commonly used as a front contact for copper indium gallium diselenide (CIGS) solar cells, but it forms a small, unfavorable conduction-band offset with the CdS layer. The optical bandgap of ZnO could easily be engineering by alloying with MgO or CdO. In this work, we try to optimize the ZnO for CIGS solar cells. The optical and electrical properties of Zn1-xMgxO:Al films fabricated by co-sputtering were studied. Two targets: ZnO:Al and MgO, were used. The ratio of ZnO/MgO was varied continuously on the 6”x6” glass substrate, and the effects of composition on the properties of the Zn1-xMgxO:Al films were investigated. The carrier concentration and mobility of the Zn1-xMgxO:Al films decreased quickly with increasing Mg content. However, the optical properties of the Zn1-xMgxO:Al films do not vary linearly with Mg content, as reported by most papers. The observed optical bandgap of Zn1-xMgxO:Al films is actually first narrowed, then increased with the Mg content. The shift in optical bandgap from narrow to wide occurs at around a composition of x = 0.07. After the point of x = 0.07, the bandgap width star increase but film sheet resistance already too low. Our result therefore suggests that the alloyed Zn1-xMgxO:Al does not benefit the CIGS solar cell.

Advanced Flexible CIGS Solar Cells Enhanced by Broadband Nanostructured Antireflection Coatings

2015 ◽  
Vol 1771 ◽  
pp. 145-150
Author(s):  
Gopal G. Pethuraja ◽  
Roger E. Welser ◽  
John W. Zeller ◽  
Yash R. Puri ◽  
Ashok K. Sood ◽  
...  
Keyword(s):  
Solar Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Specific Power ◽  
Band Spectrum ◽  
Solar Panels ◽  
Antireflection Coatings ◽  
Copper Indium Gallium Diselenide ◽  
Copper Indium ◽  
Cigs Solar Cells

ABSTRACTFlexible copper indium gallium diselenide (CIGS) solar cells on lightweight substrates can deliver high specific powers. Flexible lightweight CIGS solar cells are also primary candidates for building-integrated panels. In all applications, CIGS cells can greatly benefit from the application of broadband and wide-angle AR coating technology. The AR coatings can significantly improve the transmittance of light over the entire CIGS absorption band spectrum. Increased short-circuit current has been observed after integrating AR coated films onto baseline solar panels. NREL’s System Advisor Model (SAM) has predicted up to 14% higher annual power output on AR integrated vertical or building-integrated panels. The combination of lightweight flexible substrates and advanced device designs employing nanostructured optical coatings together have the potential to achieve flexible CIGS modules with enhanced efficiencies and specific power.

Variable Light Soaking Effect of Cu(In,Ga)Se2 Solar Cells with Conduction Band Offset Control of Window/Cu(In,Ga)Se2 Layers

2007 ◽  
Vol 1012 ◽  
Author(s):  
Takashi Minemoto ◽  
Yasuhiro Hashimoto ◽  
Takuya Satoh ◽  
Takayuki Negami ◽  
Hideyuki Takakura
Keyword(s):  
Solar Cells ◽  
Conduction Band ◽  
Buffer Layers ◽  
Window Layer ◽  
Band Offset ◽  
Conduction Band Offset ◽  
Current Voltage ◽  
Variable Light ◽  
Cigs Solar Cells ◽  
The Impact

AbstractThe impact of the conduction band offset (CBO) between window/Cu(In,Ga)Se2 (CIGS) layers on the light soaking (LS) effect in CIGS solar cells has been studied with continuous CBO control using a (Zn,Mg)O (ZMO) window layer. Two types of CIGS solar cells with different window/buffer/absorber layers configurations were fabricated, i.e., ZMO/CIGS (without buffer layer) and ZMO/CdS/CIGS structures. The CBO values between ZMO and CIGS layers were controlled to -0.15~0.25 eV. Plus and minus signs of CBO indicate the conduction band minimums of ZMO above and below that of CIGS, respectively. Current-voltage (J-V) characteristics of the solar cells with different LS durations revealed that a positive CBO value higher than 0.16 eV induces J-V curve distortion, i.e., LS effect, and all the J-V characteristics stabilized in 30 min. The degrees of the LS effect were dominated by the CBO value between ZMO and CIGS layers in the both structure regardless of the existence of CdS buffer layers. These results indicate that the LS effect is dominated by the highest barrier for photo-generated electrons in the conduction band diagram, i.e., the CBO between ZMO and CIGS layers, and quantitatively the LS effect emerges the CBO value higher than 0.16 eV.

Optimization of Graded CIGS Solar Cells Using TCAD Simulations

2012 ◽  
Vol 1447 ◽  
Author(s):  
Mankoo Lee ◽  
Dipankar Pramanik ◽  
Haifan Liang ◽  
Ed Korczynski ◽  
Jeroen van Duren
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Model Parameters ◽  
Back Side ◽  
High Productivity ◽  
Copper Indium ◽  
Cigs Solar Cells ◽  
Interface Layers ◽  
The Impact ◽  
Typical Range

ABSTRACTTo understand paths towards higher efficiency (η) for copper-indium-gallium-(sulfur)-selenide [CIG(S)Se] solar cells, we investigated a variety of absorber composition grading schemes for various back-side gallium (Ga), front-side sulfur (S), and double-graded Ga composition depth profiles in TCAD 1D/2D simulations. We fitted experimental results of a Back-Side Graded (BSG) solar cell with our TCAD models, prior to investigating other grading and interface schemes. The BSG solar cell was fabricated on a High Productivity Combinatorial (HPC™) platform based on sputtering Cu(In,Ga) followed by selenization. Our TCAD simulation methodology for optimizing CIG(S)Se solar cells started with a sensitivity analysis using 1D Solar-cell CAPacitance Simulator (SCAPS) [1] by selecting a typical range of key model parameters and analyzing the impact on η. We then used a 2D commercially-available Sentaurus simulation tool [2] to incorporate wavelength-dependent optical characteristics. As a result, we provide insight in the impact of grading schemes on efficiency for a fixed ‘material quality’ equal to an in-house BSG solar cell. We also quantify the effects of interface layers like MoSe2 at the Mo/CIG(S)Se interface, and an inverted surface layer at the CIG(S)Se/CdS interface.

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