Deposition Technologies of High-Efficiency CIGS Solar Cells: Development of Two-Step and Co-Evaporation Processes

Huang, Chen‐Fen; Chuang, Wen-Jie; Lin, Chun-Ping; Jan, Yueh-Lin; Shih, Y.C.

doi:10.3390/cryst8070296

Cited by 33 publications

(15 citation statements)

References 44 publications

(51 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Field studies, e.g., [11,16,30], have observed similar ranges of CGI and GGI atomic ratios to that which we reported in the current study. Park et al [16] investigated XRD patterns of CIGS thin films at substrate temperature ranging up to 600 • C. They found that all films which were grown at the temperature above 200 • C showed good crystallinity with FWHM value between 0.22 • and 0.35 • .…”

Section: Discussionsupporting

confidence: 89%

“…Complex structure of Cu(In,Ga)Se 2 based solar cell requires a variety of technologies for particular layer fabrication to achieve high device efficiency. This is the reason why co-evaporation method is the most used one in the process of CIGS absorber fabrication [10][11][12] while chemical bath deposition (CBD) is a very common method of CdS buffer layer fabrication [13,14]. The application of optimal methods for each structure fabrication leads to the highest efficiency of the final device.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

RF/DC Magnetron Sputtering Deposition of Thin Layers for Solar Cell Fabrication

Gulkowski

Krawczak

2020

Coatings

View full text Add to dashboard Cite

Thin film Cu(In,Ga)Se2 (CIGS)-based solar cells with relatively high efficiency and low material usage might become a promising alternative for crystalline silicon technology. The most challenging task nowadays is to decrease the PV module fabrication costs by application of easily scalable industrial process. One of the possible solutions is the usage of magnetron sputtering system for deposition of all structures applied in CIGS-based photovoltaic device. The main object of these studies was fabrication and characterization of thin films deposited by sputtering technique. Structural and electrical properties of the sputtered films were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray Powder Diffraction (XRD), and four-point probe resistivity measurements. The presented findings revealed technological parameters for which sheet resistance of molybdenum (Mo) back contact decreased up to 0.3 Ω/□ and to even 0.08 Ω/□ in case of aluminum layer. EDS analysis provided evidence for the appropriate stoichiometry of CIGS absorber (with CGI and GGI equal to 0.96 and 0.2, respectively). XRD characterization confirmed high-quality chalcopyrite polycrystalline structure of Cu(In,Ga)Se2 film fabricated at relatively low substrate temperature of 400 °C. Characteristic XRD peaks of hexagonal-oriented structures of sputtered CdS and i-ZnO layers were noticed.

show abstract

Section: Discussionsupporting

confidence: 89%

Section: Methodsmentioning

confidence: 99%

RF/DC Magnetron Sputtering Deposition of Thin Layers for Solar Cell Fabrication

Gulkowski

Krawczak

2020

Coatings

View full text Add to dashboard Cite

show abstract

“…For the three-stage co-evaporated CIGS cell, as the thickness of the i-ZnO layer increased from 30 nm to 90 nm, the shunt resistance (R SH ) of the cell was significantly increased from 529.6 to 1126 Ω cm 2 , which results in the improvement of the V OC (from 0.467 V to 0.507 V), FF (from 61.8% to 66.3%) and conversion efficiency (from 10.1% to 11.8%), as displayed in Figure 12a. The improvement in the shunt resistance of the device with the i-ZnO thickness of 90 nm was due to the full coverage of the possible shunt paths within the CIGS/CdS layers with i-ZnO [31,49]. However, a further increas of i-ZnO thickness to 170 nm decreased the device performance parameters, especially the lowest J SC as the thick ZnO layer weakened the built-in field by spreading the space charge region [31].…”

Section: Resultsmentioning

confidence: 99%

Optimization of Intrinsic ZnO Thickness in Cu(In,Ga)Se2-Based Thin Film Solar Cells

2019

View full text Add to dashboard Cite

The typical structure of high efficiency Cu(InGa)Se2 (CIGS)-based thin film solar cells is substrate/Mo/CIGS/CdS/i-ZnO/ZnO:Al(AZO) where the sun light comes through the transparent conducting oxide (i.e., i-ZnO/AZO) side. In this study, the thickness of an intrinsic zinc oxide (i-ZnO) layer was optimized by considering the surface roughness of CIGS light absorbers. The i-ZnO layers with different thicknesses from 30 to 170 nm were deposited via sputtering. The optical properties, microstructures, and morphologies of the i-ZnO thin films with different thicknesses were characterized, and their effects on the CIGS solar cell device properties were explored. Two types of CIGS absorbers prepared by three-stage co-evaporation and two-step sulfurization after the selenization (SAS) processes showed a difference in the preferred crystal orientation, morphology, and surface roughness. During the subsequent post-processing for the fabrication of the glass/Mo/CIGS/CdS/i-ZnO/AZO device, the change in the i-ZnO thickness influenced the performance of the CIGS devices. For the three-stage co-evaporated CIGS cell, the increase in the thickness of the i-ZnO layer from 30 to 90 nm improved the shunt resistance (RSH), open circuit voltage, and fill factor (FF), as well as the conversion efficiency (10.1% to 11.8%). A further increas of the i-ZnO thickness to 170 nm, deteriorated the device performance parameters, which suggests that 90 nm is close to the optimum thickness of i-ZnO. Conversely, the device with a two-step SAS processed CIGS absorber showed smaller values of the overall RSH (130–371 Ω cm2) than that of the device with a three-stage co-evaporated CIGS absorber (530–1127 Ω cm2) ranging from 30 nm to 170 nm of i-ZnO thickness. Therefore, the value of the shunt resistance was monotonically increased with the i-ZnO thickness ranging from 30 to 170 nm, which improved the FF and conversion efficiency (6.96% to 8.87%).

show abstract

“…The one-step and three-step processes have been studied extensively, and the films prepared by each method have been compared to determine which process produces the better CIGS films. The differences in band gap profiles, crystalline phases, growth mechanisms, and element distributions between films prepared by the one-step and three-step processes are reported in the literature. − These reports showed that the films made with the three-step process had a slightly better electrical performance than those made with the one-step process due to the films made with the three-step process having a Cu-poor surface, a double-graded band gap, good stoichiometry control, and a large-grained absorber. Notably, a small-area CIGS-type solar cell based on three-step co-evaporation was recently demonstrated to have an efficiency surpassing 20% in the laboratory, which is better performance than that exhibited by CIGS cells produced by other processes as well as that of conventional multicrystalline Si devices …”

Section: Introductionmentioning

confidence: 95%

Multistage Degradation Mechanisms in Cu(In, Ga)Se₂ Photovoltaic Modules Prepared by Co-Evaporation: Toward High Performances and Enhanced Stability

Cho

Kim

Park

et al. 2019

ACS Appl. Energy Mater.

View full text Add to dashboard Cite

This study compared the stability and durability of copper indium gallium selenide (CIGS)-type solar cells prepared using one-step and three-step co-evaporation methods by investigating the causes of degradation in each layer in detail. Measurements recorded using a solar simulator showed that the sample prepared using the three-step method had better device performance owing to the large-grained structure of the CIGS absorber layer, which reduced the carrier recombination. Focusing on the discrepancy in grain size, multifarious degradation tests were conducted according to the IEC 61646 standard to evaluate the stability of the cells under harsh environments such as high humidity (85%), high temperature (85 °C), and mechanical load. Damp heat (85%/85 °C) did not affect the CIGS resistivities in either sample, whereas all the aluminum-doped zinc oxide layers degraded, as determined by confirming the chemisorbed oxygen by exposure to a hot, humid environment. After 200 thermal cycles, the CIGS layers in both samples were mainly degraded while there were no changes in the resistivities of the AZO layer in either sample. The thermal cycling test highlights that the initial resistivities of the one-step sample showed a decisive change before and after thermal cycling compared to the three-step sample. This change might be caused by carriers being scattered at the grain boundaries. Although there were no big differences in the FT-IR spectra before and after thermal cycling, both XRD and XPS results confirmed that not only copper indium sulfide selenium elements of the secondary phase were newly observed by sulfide diffusion from the CdS layer but also that each element (Cu, In, Ga, and Se) was slightly oxidized by the rapid temperature variation from −45 to 85 °C. These results prove that the three-step co-evaporation method can produce cells with much higher stability and durability, even when operated under high humidity and temperature conditions.

show abstract

Deposition Technologies of High-Efficiency CIGS Solar Cells: Development of Two-Step and Co-Evaporation Processes

Cited by 33 publications

References 44 publications

RF/DC Magnetron Sputtering Deposition of Thin Layers for Solar Cell Fabrication

RF/DC Magnetron Sputtering Deposition of Thin Layers for Solar Cell Fabrication

Optimization of Intrinsic ZnO Thickness in Cu(In,Ga)Se2-Based Thin Film Solar Cells

Multistage Degradation Mechanisms in Cu(In, Ga)Se₂ Photovoltaic Modules Prepared by Co-Evaporation: Toward High Performances and Enhanced Stability

Contact Info

Product

Resources

About

Deposition Technologies of High-Efficiency CIGS Solar Cells: Development of Two-Step and Co-Evaporation Processes

Cited by 33 publications

References 44 publications

RF/DC Magnetron Sputtering Deposition of Thin Layers for Solar Cell Fabrication

RF/DC Magnetron Sputtering Deposition of Thin Layers for Solar Cell Fabrication

Optimization of Intrinsic ZnO Thickness in Cu(In,Ga)Se2-Based Thin Film Solar Cells

Multistage Degradation Mechanisms in Cu(In, Ga)Se2 Photovoltaic Modules Prepared by Co-Evaporation: Toward High Performances and Enhanced Stability

Contact Info

Product

Resources

About

Multistage Degradation Mechanisms in Cu(In, Ga)Se₂ Photovoltaic Modules Prepared by Co-Evaporation: Toward High Performances and Enhanced Stability