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Light intensity dependence of CIGS solar cells. a J-V curves and corresponding solar cell parameter variations observed for 0.5 cm 2 size PhL-separated (red) and MS-separated (black) CIGS single-cells. b Photographs of practical usage of lightweight and flexible CIGS minimodules lighting a green LED under approximately 200 lx illumination.
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Lightweight and flexible photovoltaic solar cells and modules are promising technologies that may result in the wide usage of light-to-electricity energy conversion devices. This communication presents the prospects of Cu(In,Ga)Se2 (CIGS)-based lightweight and flexible photovoltaic devices. The current status of flexible CIGS minimodules with photo...
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... variations in photovoltaic performance with light intensity (irradiance dependence) were measured under simulated sunlight with neutral density (ND) filters. Figure 5a shows the J-V curves and variations in solar cell parameters measured under various light intensity conditions ranging from 1 to 0.01 sun (nominally equivalent to from 100,000 to 1000 lx). For this experiment, two small-area (0.5 cm 2 ) single-cells randomly selected from PhL-and MS-separated RbF-PDT CIGS devices with photovoltaic efficiency values of 20.1% and 18.6% at 1 sun (with ARC and without HLS treatments), respectively, were used. ...
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... ARC and without HLS treatments), respectively, were used. It is known that the photovoltaic performance under low illumination conditions significantly depends on R sh , and CIGS cells with relatively low R sh show a steep drop in V OC and FF with decreasing light intensity 31 . This trend could be observed for the MS-separated CIGS cell shown in Fig. 5a. In contrast, the PhL-separated cell showed no such drastic degradation in performance under low illumination conditions. On the contrary, a slight improvement was observed in the photovoltaic efficiency value with decreasing light intensity. Note that the R sh values for the MS and PhL devices calculated at 1 sun were 916 and 4670 Ω ...
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... result indicates that the effect of the cell separation process on photovoltaic performance, i.e., the MS technique conventionally used for cell and module fabrication, is nonnegligible and an important issue as well as the interface and bulk issues of CIGS devices. Figure 5b shows the lightweight and flexible CIGS minimodules (size: 8 × 10 cm 2 and 2 × 10 cm 2 ; P1: laser scribing; P2 and P3: MS, demonstration of products fabricated using a relatively low photovoltaic efficiency [~15% or less] minimodules) generating electricity and lighting a green light-emitting diode under room light (fluorescent tubes) with ~200 lx (nominally equivalent to 0.002 sun) illumination, indicating that CIGS solar modules can be useful light-harvesting devices even under low illumination conditions, such as on the floor in an office. Notably, these CIGS solar minimodules were fabricated using conventional MS for the P3 patterning process, and, thus, further improvements are expected with the modification of the P3 patterning. ...
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... cell parameters were performed with a direction from J SC to V OC at 25 °C under 100 mW cm −2 (1 sun, AM 1.5 G) illumination and dark conditions. The light intensity was adjusted using ND filters for irradiance dependence measurements. An MgF 2 ARC was used for minimodules #1 and #2 and small-area cells used for irradiance dependence studies (Fig. 5), whereas no ARC was used for RbF-PDT, MS, and PhL comparative studies (Fig. 4). The diode parameters of small-area cells were calculated from light and dark J-V data of the highest photovoltaic efficiency solar cells in each device type (w/ or w/o RbF-PDT and MS or PhL) using the single diode model 34,35 . The R sh values were ...
Citations
... Several thin-film solar cells, such as those based on Cu(In, Ga)Se 2 (CIGS), CdTe, and amorphous Si, have been developed as lightweight and flexible modules [14][15][16][17]. Although these modules have a smaller market share than c-Si solar cells, their substrates are two orders of magnitude thinner. ...
... Three primary techniques include PDT (post-deposition treatment), adding an alkalicontaining precursor layer, and added functionality to the back contact or the barrier layers 48,50,64 . Furthermore, depending on the technique and whether light or heavy alkali is used, their impact might vary considerably 65 . For more details on these strategies, readers are encouraged to see the exceptional review from INL and HZB 66 . ...
Two primary engineering challenges are en route to fabricating high-performance flexible stainless-steel based Cu(In,Ga)(S,Se) 2 solar cells; Growing absorbers without contamination from the substrate, and providing alkali dopants to the absorber. The former is chiefly addressed by introducing a barrier layer, and the latter by post-deposition treatment or including dopant-containing layers in the stack. Here we organize these solutions and different approaches in an accessible scheme. Additionally, reports on interaction between contamination and alkali elements are discussed, as is the impact of barrier layer properties on the interconnect technology. Lastly, we make recommendations to consolidate the multitude of sometimes inharmonious solutions.
... CIGSe TFSC, which classically involves a multi-layered stack of Al:ZnO/i:ZnO/CdS/CIGSe/Mo on a glass substrate, monolithic integration comprises three different types of scribing (commonly known as P1, P2 and P3) as shown in Fig. 1. Electrical isolation of Molybdenum (Mo/Glass) is called P1 scribing and is generally processed using a laser [4]. Mechanical patterning of CdS/CIGS up to Mo, followed by i:ZnO/Al:ZnO coating, allows series contact between Mo and bilayer i:ZnO/Al:ZnO, known as P2 scribing. ...
Cu(In,Ga)Se2 (CIGSe) thin film solar cell (TFSC) is an emerging photovoltaic technology with lab-scale device efficiency surpassing 23% and monolithically integrated module efficiency ranging from 17–19%; it is anticipated to meet escalating global electricity demand. The division of a large photovoltaic cell into serially interconnected smaller devices is known as monolithic integration. To reduce shunting losses, a monolithic integration configuration of CIGSe TFSC comprising stacks of Al:ZnO/i:ZnO/CdS/CIGSe/Mo/Glass is adapted, often by combination of laser-mechanical scribing operations during the device fabrication process. The traditional mechanical scribing procedure, which engages sharp ceramic tips, is sluggish (< 0.2 m/s) and produces broader scribing widths (> 100 µm). The module's scribing area is a dead zone and a loss of active photovoltaic region that must be minimized. Given this, we report rapid (1 m/s) nanosecond pulsed fiber laser-driven micro-patterning of CdS/CIGSe/Mo/Glass (P2 scribing) and Al:ZnO/i:ZnO/CdS/CIGSe/Mo/Glass (P3 scribing) stacks, which replaces typical sub-optimal mechanical scribing. The electrical, morphological and compositional analysis of scribed structures confirmed a significant reduction in scribe widths (< 50 µm) using a laser with 1064 nm wavelength and pulse width 25 ns, a commonly utilized configuration for scribing of Mo thin film electrodes. The process eventually reduces the dead zone and increases the overall active area in the module.KeywordsScribingCIGSeThin filmsSolar modulesLaserNanosecond
Increasing the electric field in a solar cell is of importance to alleviate the carrier recombination and thus to increase the power conversion efficiency (PCE). In this paper, a strategy is reported to enhance the internal electric field of Cu(In,Ga)(Se,S)2 (CIGS) solar cells by inserting a ferroelectric BaTiO3 (BTO) layer into the device for the first time. The BTO location in the CIGS solar cell is found to play a vital role in the performances, which is due to the adjustment of the direction of BTO depolarization field. Impressively, the PCE is increased from 4.83% to 16.07% when the BTO depolarization field direction shifts from the opposite to the same direction to the p–n junction electric field. The improved PCE is due to the enhanced open‐circuit voltage (Voc), which suppresses carrier recombination and thus boosts the short‐circuit current density (Jsc) from 14.09 to 32.69 mA cm⁻². These results unlock an effective strategy to improve the PCE of a CIGS solar cell by the application of a ferroelectric depolarization field. The facile deposition of BTO via sputtering method at room temperature enables its wide application in other solar cells to boost the PCEs.
Herein, a theoretical investigation is conducted on grain‐size inhomogeneity's impact and grain boundaries’ (GBs’) electrical nature in thin‐film solar cells. Using the Matthiessen rule, grain‐size‐dependent mobility is derived in polycrystalline material. The obtained grain‐size‐dependent mobility values are fed into the Poisson solver to calculate device performance. The severity of grain sizes in the lower region determines how grain size affects the photovoltaic performance by grain‐size‐dependent efficiency simulation. Low grain sizes become critical, especially for low‐thickness absorbers. The second aspect of the study assesses potential variation at GBs to reveal the impact of the electrical properties of GBs. Evidence shows that the acceptor defects at GB are benign for device performance, causing upward band bending at the GB and acting as electron barriers. Device performance is adversely affected by donor defects at GBs due to downward band bending. As summarized in the findings, the polycrystallinity‐induced cause–effect relationships of grains are likely to interest solar cell researchers.
This study aimed to fabricate copper indium gallium diselenide (CIGSe) thin films using a novel two-step approach. Firstly, we deposited metallic precursors (Cu/In/Ga) onto a Mo-coated stainless steel substrate using thermal evaporation at unintentional substrate temperature. Subsequently, selenization was carried out in a furnace under the presence of an inert gas. The quality of the CIGSe thin films was analyzed to explore the influence of selenization temperature (450-550°C) and duration (30 and 60 minutes), while maintaining an inert atmosphere inside the selenization furnace. The structural analysis revealed the progressive development of additional phases over time, resulting in the formation of a complete chalcopyrite CIGSe structure with the preferred reflection on the (112) plane. The absorber layer exhibited a thickness of 2 µm, with atomic ratios of 0.83 for Cu/(In+Ga) and 0.24 for Ga/(In+Ga) in the film selenized at 550°C. P-type conductivity was observed in the CIGSe thin film, with a carrier concentration of up to 1017 cm-3, and it displayed a well-defined and uniform morphology characterized by a large grain size of approximately 0.9 µm. Utilizing the optimized conditions, we successfully fabricated solar cells on a flexible substrate, achieving a photoconversion efficiency of up to 9.91%. This research delves into the impact of selenization parameters on the growth of CIGSe absorber layers and introduces a new approach that could significantly influence the feasibility and industrialization of flexible solar cells.
Due to the challenging issues like high heat generation concerned with hardened steel machining, therefore cutting fluid has been used for removing the more higher cutting temperature. Furthermore, use of nanolubrication system makes the cutting environment more sustainable. The present work represents the impacts of cutting parameters such as cutting speed, feed rate, depth of cut and LRT 30 mineral oil-based ZrO2 nanofluid concentrations in hard turning of AISI D2 steel. The ZrO2 nanofluid was first time implemented for cooling purpose in hard turning application. The performance was examined by taking average surface roughness, tool flank wear, cutting power and cutting temperature results. Experimental results found that the 0.20% nanofluid concentration was the better choice among all adopted weight concentrations (0.05%, 0.2% and 0.5%) of nanofluid. Abrasion, cutting edge chipping and adhesion were found to be the principal wear mode. Also, acceptable range of surface roughness (0.498–0.665 micron) was seen in the entire investigations.KeywordsHard turningZrO2CVDNanofluidCutting power
