共查询到20条相似文献,搜索用时 0 毫秒
1.
Tokio Nakada Hiroki Ohbo Takayuki Watanabe Hidenobu Nakazawa Masahiro Matsui Akio Kunioka 《Solar Energy Materials & Solar Cells》1997,49(1-4)
Surface sulfurization was developed as a technique for fabricating efficient ZnO : Al/CdS/graded Cu(In,Ga)(S,Se)2/ Mo/glass solar cells. Prior to the sulfurization, single-graded Cu(In,Ga)Se2 (CIGS) films were deposited by a multi-stage process. The sulfurization of CIGS films was carried out using a H2S---Ar mixture at elevated temperatures. The crystallographic and compositional properties of the absorber layers were investigated by XRD, SEM and AES analyses. After sulfurization, sulfur atoms were substituted for selenium atoms at the surface layer of CIGS films to form a Cu(In,Ga)(S,Se)2 absorber layer. The diffusion of sulfur depends strongly on the grain structure of CIGS film. The cell efficiency of the 8–11% range before sulfurization was improved dramatically to 14.3% with Voc = 528 mV, Jsc = 39.9 mA/cm2 and FF = 0.68 after the sulfurization process. 相似文献
2.
D. Abou-Ras J. DietrichJ. Kavalakkatt M. NichterwitzS.S. Schmidt C.T. KochR. Caballero J. KlaerT. Rissom 《Solar Energy Materials & Solar Cells》2011,95(6):1452-1462
The present work gives an overview of how electron microscopy and its related techniques are used to analyze individual layers and their interfaces in Cu(In,Ga)(S,Se)2 thin-film solar cells. Imaging of samples can be performed at scales of down to the (sub)angstroms range. At similar spatial resolutions, information on composition can be gathered by means of energy-dispersive X-ray spectroscopy (EDX) and on spatial distributions of electrostatic Coulomb potentials in the specimen by applying electron holography. Microstructural and compositional properties as well as charge-carrier collection and radiative recombination behavior of the individual layers are accessible by use of electron backscatter diffraction, EDX, electron-beam-induced current (EBIC) and cathodoluminescence measurements, available in scanning electron microscopy. The present contribution gives an overview of the various scanning and transmission electron microscopy techniques applied on Cu(In,Ga)(S,Se)2 thin-film solar cells, examples from case studies, and also demonstrates how these techniques may be combined in order to improve the analysis. Particularly, EBIC results show a reduced charge-carrier collection at Cu(In,Ga)Se2 grain boundaries, while no indication was found for a charge accumulation at the grain boundaries by electron holography. 相似文献
3.
Shiro Nishiwaki Takuya Satoh Yasuhiro Hashimoto Shin-Ichi Shimakawa Shigeo Hayashi Takayuki Negami Takahiro Wada 《Solar Energy Materials & Solar Cells》2003,77(4):1213
Cu(In,Ga)Se2 (CIGS) surface was modified with Zn doping using vacuum evaporation. Substrate temperatures and exposure times during the Zn evaporation were changed to control a distribution of Zn in the CIGS films. Diffusion of Zn in the CIGS films was observed at the substrate temperature of over 200°C. The diffusion depth of Zn increases with increasing the exposure time at the substrate temperature of 300°C. Solar cells were fabricated using the Zn doped CIGS films. A distribution of the efficiencies decreases with increasing the exposure time of Zn vapor. The doping of Zn at the film surface improved reproducibility of a high fill factor and efficiency. A solar cell fabricated using the CIGS film modified with Zn doping showed an efficiency of 14.8%. 相似文献
4.
Polycrystalline CuIn1 − xGaxSe2 (0 ≤ x < 0.3) films (CIGS) were deposited by coevaporating the elements from appropriate sources onto glass substrates (substrate temperature 720 to 820 K). Photoconductivity of the polycrystalline CIGS films with partially depleted grains were studied in the temperature range 130–285 K at various illumination levels (0–100 mW/cm2). The data at low temperature (T < 170 K) were analyzed by the grain boundary trapping model with monovalent trapping states. The grain boundary barrier height in the dark and under illumination were obtained for different x-values of CuIn1−xGaxSe2 films. Addition of Ga in the polycrystalline films resulted in a significant decrease in the barrier height. Variation of the barrier height with incident intensity indicated a complex recombination mechanism to be effective in the CIGS films. 相似文献
5.
Toshiyuki Yamaguchi Toshitsugu Kobata Shigetoshi Niiyama Takashi Nakamura Akira Yoshida 《Solar Energy Materials & Solar Cells》2003,75(1-2):87-92
Thin films of Cu–In–Ga–Se alloy system with various composition were prepared by thermal crystallization from In/CuInGaSe/In precursor. Electron probe microanalysis and X-ray diffraction study revealed that these samples were assigned to chalcopyrite Cu(In,Ga)Se2 or ordered vacancy compound Cu(In,Ga)2Se3.5. Solar cell with ZnO:Al/i–ZnO/CdS/Cu(In,Ga)Se2/Mo/soda-lime glass substrate structure was fabricated by using thermal crystallization technique, and demonstrated a 9.58% efficiency without AR-coating. 相似文献
6.
Polycrystalline thin films of CuInSe2 and Cu(In,Ga)Se2 (CIGS) were grown on both polished Mo substrates and Mo-coated glass substrates by one-step electrodeposition. All the as-deposited films have been annealed in vacuum at 450°C for a short time to improve the crystalline properties. The films have been characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The results indicate that the crystallization of the films was greatly improved after annealing. Further more, a CIGS film with 23 at% Ga was obtained. 相似文献
7.
The efficiencies of Cu(In,Ga)Se2/CdS/ZnO solar cell devices in which the absorbers are produced by classical two-step processes are significantly lower that those in which co-evaporated absorbers are used. A significant problem related to two-step growth processes is the reported segregation of Ga towards the Mo back contact, resulting in separate CuInSe2 and CuGaSe2 phases. Furthermore, it is often reported that material losses (especially In and Ga) occur during high-temperature selenization of metallic precursors. In this study, X-ray fluorescence (XRF) analysis was used to study the diffusion behaviour of the chalcopyrite elements in single-stage and two-stage processed Cu(In,Ga)Se2 thin films. This relatively simple characterization technique proved to be very reliable in determining the degree of selenium incorporation, possible material losses and the in-depth compositional uniformity of samples at different stages of processing. This information is especially important in the case of two-stage growth processes, involving high-temperature selenization steps of metallic precursors. Device quality Cu(In,Ga)Se2 thin films were prepared by a relatively simple and reproducible two-step growth process in which all the metals were evaporated from one single crucible in a selenium-containing environment. The precursors were finally treated in an H2Se/Ar atmosphere to produce fully reacted films. XRF measurement indicated no loss of In or Ga during this final selenization step, but a significant degree of element diffusion which depended on the reaction temperature. It was also possible to produce Cu(In,Ga)Se2 thin films with an appreciable amount of Ga in the near-surface region without separated CuInSe2 and CuGaSe2 phases. 相似文献
8.
Shintaro OsadaYasuhiro Abe Takaya AnegawaTakashi Minemoto Hideyuki Takakura 《Solar Energy Materials & Solar Cells》2011,95(1):223-226
Cu(In,Ga)Se2 (CIGS) solar cells with a superstrate structure were fabricated using a lift-off process. To widen the variety of substrate choices for CIGS solar cells, a lift-off process was developed without an intentional sacrificial layer between the CIGS and Mo back-contact layers. The CIGS solar cells fabricated on Mo/soda-lime glass (SLG) were transferred to an alternative SLG substrate. The conversion efficiency of the CIGS solar cells with the superstrate structure was 5.1%, which was almost half that of the CIGS solar cells with a substrate structure prior to the lift-off process. The low conversion efficiency was caused by the high series resistance and low shunt resistance, which would be due to the junction resistance between the CIGS/back contact and cracks introduced during the lift-off process, respectively. 相似文献
9.
Thin films of Cu(In,Ga)Se2 were prepared by thermal crystallization on the sputtered Mo/substrate and characterized. MoSe2 layer was formed at the interface between Cu(In,Ga)Se2 and Mo layers after the thermal crystallization. The graded Ga concentration in crystallized Cu(In,Ga)Se2 thin films was confirmed. Cu(In,Ga)Se2 thin films prepared on the Mo/soda-lime glass had large and columnar grains rather than those on the Mo/quartz substrate. 相似文献
10.
Takuya Satoh Yasuhiro Hashimoto Shin-ichi Shimakawa Shigeo Hayashi Takayuki Negami 《Solar Energy Materials & Solar Cells》2003,75(1-2):65-71
We have developed the flexible Cu(In,Ga)Se2 (CIGS) solar cells on the stainless steel substrates with the insulating layer for the fabrication of the integrated module. The CIGS films have strong adhesion to the Mo films with insulating layers. An efficiency of 12.3% was achieved by the flexible CIGS solar cell with a structure of ITO/ZnO/CdS/CIGS/Mo/SiO2/stainless steel. The insertion of the SiO2 insulating layer did not have an influence on the formation of the CIGS film and solar cell performances. 相似文献
11.
Xuege Wang Sheng. S. Li W.K. Kim S. Yoon V. Craciun J.M. Howard S. Easwaran O. Manasreh O.D. Crisalle T.J. Anderson 《Solar Energy Materials & Solar Cells》2006,90(17):2855-2866
Rapid thermal annealing (RTA), with fast ramp rate, was performed on several Cu(In,Ga)Se2 (CIGS) films and solar cells under various peak annealing temperatures and holding times. Characterizations were made on CIGS films and cells before and after RTA treatments to study effects of RTA on the CIGS film properties and cell performance. In addition, AMPS-1D device simulation program was used to study effects of defect density on the cell performance by fitting the experimental data of RTA-treated CIGS cells. The results show that RTA treatments under optimal annealing condition can provide significant improvements in the electrical properties of CIGS films and cell performance while preserving the film composition and microstructure morphology. 相似文献
12.
This work investigates NaF, on Mo coated sodium barrier glass, as a sodium precursor for the growth of Cu(In, Ga)Se2 for thin film solar cells. These precursor layers are investigated by X-ray photoelectron spectroscopy (XPS) before and after annealing, and after exposure to selenium. XPS is also performed on the Cu(In, Ga)Se2 layer, deposited with NaF. The influence of the NaF on the absorber growth is studied by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The electrical properties are investigated by cell fabrication and characterization. Cell results are comparable when NaF or out-diffusion of sodium from the soda lime glass are used. 相似文献
13.
S. Nishiwaki T. Satoh S. Hayashi Y. Hashimoto S. Shimakawa T. Negami T. Wada 《Solar Energy Materials & Solar Cells》2001,67(1-4)
Improved preparation process of a device quality Cu(In,Ga)Se2 (CIGS) thin film was proposed for production of CIGS solar cells. In–Ga–Se layer were deposited on Mo-coated soda-lime glass, and then the layer was exposed to Cu and Se fluxes to form Cu–Se/In–Ga–Se precursor film at substrate temperature of over 200°C. The precursor film was annealed in Se flux at substrate temperature of over 500°C to obtain high-quality CIGS film. The solar cell with a MgF2/ITO/ZnO/CdS/CIGS/Mo/glass structure showed an efficiency of 17.5% (Voc=0.634 V, Jsc=36.4 mA/cm2, FF=0.756). 相似文献
14.
M. E. Calixto R. N. Bhattacharya P. J. Sebastian A. M. Fernandez S. A. Gamboa R. N. Noufi 《Solar Energy Materials & Solar Cells》1998,55(1-2)
CuIn1−xGaxSe2 (CIGS) thin films were formed from an electrodeposited CuInSe2 (CIS) precursor by thermal processing in vacuum in which the film stoichiometry was adjusted by adding In, Ga and Se. The structure, composition, morphology and opto-electronic properties of the as-deposited and selenized CIS precursors were characterized by various techniques. A 9.8% CIGS based thin film solar cell was developed using the electrodeposited and processed film. The cell structure consisted of Mo/CIGS/CdS/ZnO/MgF2. The cell parameters such as Jsc, Voc, FF and η were determined from I–V characterization of the cell. 相似文献
15.
To reduce cracks caused by the lift-off process in a Cu(In,Ga)Se2 (CIGS) layer, we focused on increasing the transferred layer thickness. We investigated the relationship between crack formation and the transferred layer thickness which is controlled by a Mo back electrode thickness. We found that the cracks were reduced by increasing the back electrode thickness. We suggest that the dominant factor of the crack reduction is attributed to the increase of the film hardness by increasing the Mo back electrode thickness. Next, we applied this crack reduction method to the solar cell fabrication. From the comparison of the 0.2-μm-thick Au single and 0.2-μm-thick Au/1.6-μm-thick Mo stacked back electrode lift-off CIGS solar cells, we investigated advantages of our crack reduction method. The crack formation was reduced only for the stacked back electrode lift-off solar cell. From the spatial distribution evaluation of an external quantum efficiency (EQE), we found that the crack reduction leads to not only the increase of an average EQE but also the decrease of EQE dispersion. In the solar cell parameters, the stacked back electrode lift-off solar cell without cracks showed the short-circuit current density and fill factor higher than those of the single back electrode lift-off solar cell with cracks. As a result, the conversion efficiency improvement as high as approximately 1% (an absolute value) was obtained. Moreover, the stacked back electrode lift-off solar cell showed the diode parameters (the diode ideality factor, the saturation current density, and series resistance) better than those of the single back electrode lift-off solar cell in the dark current density-voltage characteristics. We concluded that this high fill factor was attributed to the better diode performance. We therefore found that the stacked back electrode structure was very effective for improving the solar cell performance using the lift-off process. 相似文献
16.
Tokio Nakada Hiroki Ohbo Masakazu Fukuda Akio Kunioka 《Solar Energy Materials & Solar Cells》1997,49(1-4)
The effects of sodium on off-stoichiometric Cu(In,Ga)Se2 (CIGS)-based thin films and solar cells were investigated. The CIGS-based films were deposited with intentionally incorporated Na2Se on Mo-coated SiOx/soda-lime glass substrates by a multi-step process. By sodium control technique high-efficiency ZnO : Al/CdS/CIGS solar cells with efficiencies of 10–13.5% range were obtained over an extremely wide Cu/(In + Ga) ratio range of 0.51–0.96, which has great merit for the large-area manufacturing process. The improved efficiency in the off-stoichiometric regions is mainly attributed to the increased acceptor concentration and the formation of the Cu(In,Ga)3Se5 phase films with p-type conductvity. A new type of solar cell with p-type Cu(In,Ga)3Se5 phase absorber materials is also suggested. 相似文献
17.
Takayuki Negami Yasuhiro Hashimoto Shiro Nishiwaki 《Solar Energy Materials & Solar Cells》2001,67(1-4)
An efficiency of over 18% have been achieved in Cu(In,Ga)Se2 (CIGS) thin-film solar cells. Solar cell parameters were estimated for the cells with efficiencies of more and less than 18%. A diode quality factor n and forward current (saturated current) J0 of the cell with over 18% efficiency are lower than those with below 18% efficiency. This would be attributed to sufficient coverage of the CdS film with excellent uniformity as a buffer and/or window layer over the CIGS film because the process of CdS film formation was improved. 相似文献
18.
J. Kessler J. Wennerberg M. Bodegrd L. Stolt 《Solar Energy Materials & Solar Cells》2003,75(1-2):35-46
In this contribution, we present results and the philosophy of our mini-module efforts. These efforts have achieved world record levels as well as a reproducible process. Various mini-module designs are tested using two different baseline Cu(In,Ga)Se2 deposition recipes. Gridded mini-modules achieve highest efficiencies and are much less demanding on the ZnO:Al top contact than their conventional counterpart. For all of the designs tested, our experimental results are in the order of the expectations from our modeling. Gridded modules can achieve efficiency levels very close to those of the cells. 相似文献
19.
Miguel A. Contreras H. Wiesner J. Tuttle K. Ramanathan R. Noufi 《Solar Energy Materials & Solar Cells》1997,49(1-4)
Considering the chalcopyrite/defect-chalcopyrite junction model for Cu(In1−xGax)Se2-based devices and our previously reported findings for the Cu(In1−xGax)3Se5 defect chalcopyrites, we have postulated that uniform high-Ga-content photovoltaic structures (with x > 0.35) do not yield acceptable device performance due to the electrical and structural differences between both types of materials (chalcopyrite and defect-chalcopyrite).In this contribution, the structural properties of the surface region of Ga containing absorber materials have been studied by grazing incidence X-ray diffraction. We find that there are significant differences between surface and bulk. A structural model is proposed for the growth of the chalcopyrite/defect-chalcopyrite junction relative to its Ga content. And we demonstrate that closely lattice matched high-Ga-content structures (x > 0.35) can produce solar cells withv acceptable performances. The high-voltage and low-current electrical outputs from high Ga structures are very desirable in module fabrication because overall resistive losses can be substantially reduced. 相似文献