Bifacial concentrator Ag-free crystalline n-type Si solar cell (original) (raw)
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Results obtained in frame of an innovative approach for fabrication of the bifacial low concentrator Ag free Cz silicon solar cells based on Indium-Tin-Oxide(ITO)/(p + nn +)Cz-Si/Indium-Fluorine-Oxide (IFO) structure (n-type cell) as well as on IFO/(n + pp +)Cz-Si/ITO structure (p-type cell) are presented in this work. The (p + nn +)Cz-Si and (n + pp +)Cz-Si structures were produced by diffusion of boron and phosphorus from deposited Band P-containing glasses followed by an etch-back step. The n + surface of the structures was textured, whereas the p + surface remained planar. Transparent conducting oxide (TCO) films, which act as passivating and antireflection electrodes, were deposited by ultrasonic spray pyrolysis method on both sides. The contact pattern of copper wire was attached by the low-temperature (160 °C) lamination method simultaneously to the front and rear TCO layers as well as to the interconnecting ribbons arranged outside the structure. The shadowing from the contacts is in the range of ~4%. The resulting solar cells showed front/rear efficiencies
n-Si Bifacial Concentrator Solar Cell
Various approaches have been developed for reducing the cost of the photoelectricity produced by silicon solar cells (SCs). Of highest priority among these approaches are improvement of the efficiency of the SCs, transition from pSi to nSi, light concentration, and use of bifacial SCs. In the present study, an SC combining all these approaches has been developed. In this SC, transparent conducting oxides serve as antireflection and passivating electrodes in an indium–tin–oxide/(p+nn+)Si/indium–fluorine–oxide structure fabricated from CzSi with wire contacts (Laminated Grid Cell design). The SC has front/rear efficiencies of 16.5–16.7/15.1–15.3% X (under 1–3 suns). This result is unique because the combination of bifaciality and concentrator operation has no analogs and the SC compares well with the world standard among both bifacial and concentrator SCs.
15th International Conference on Concentrator Photovoltaic Systems (CPV-15), 2019
We present Ag-free low-concentrator bifacial indium-fluorine-oxide (IFO)/(n + pp +)Cz-Si/indium-tin-oxide (ITO) solar cells based on: (i) a shallow phosphorus-doped n +-emitter; (ii) an easy-to-fabricate screen-printed Al-alloyed Al-p + back-surface-field (BSF); (iii) transparent conductive IFO and ITO layers grown by ultrasonic spray pyrolysis, which act as passivating and antireflection electrode; (iv) Ag-free multi-wire metallization of copper wire attached by the low-temperature lamination method simultaneously to the front IFO layer, rear ITO layer as well as to the interconnecting ribbons arranged outside the structure using transparent conductive polymer films. For the manufacture of solar cells, we used standard commercially available SiNx/(n + pp +)Cz-Si/Al structures. After removal of the residual Al paste, the Al-p + layer was thinned by one-sided etchback process. A number of solar cells were prepared differing in the sheet resistance of the Al-p + layer (Rp+), which ranged from 14 Ω/sq (original, non-etched Al-p + layer) to 123 Ω/sq. It was found that thinning of the Al-p + layer (increase in Rp+) greatly improved all the parameters of solar cells. The cell with Rp+ = 81 Ω/sq showed the best combination of conversion parameters. Under 1-sun front/rear illumination, the conversion efficiency of this cell is 17.5%/11.2% (against 16.0%/7.5% for the cell with Rp+ = 14 Ω/sq). At 1-sun front illumination and 20/50% albedo of 1-sun illumination, the equivalent efficiency is equal to 19.9%/23.5% (against 17.7%/20.1% for the cell with Rp+ = 14 Ω/sq). At a sunlight concentration ratio (kC) of 2.3-2.7 suns, the cells with Rp+ in the range 45-123 Ω/sq showed approximately similar maximum front-side efficiency, 17.5-17.9%. However, the operating range of sunlight concentration ratio (kC,OR) determined as η(kC,OR) = η(kC = 1) showed a tendency to decrease from 5.8 ± 0.6 suns to 4 ± 0.5 suns with an increase in Rp+ from 14-45 Ω/sq to 63-123 Ω/sq.
ZnO transparent conductive oxide for thin film silicon solar cells
2010
There is general agreement that the future production of electric energy has to be renewable and sustainable in the long term. Photovoltaic (PV) is booming with more than 7GW produced in 2008 and will therefore play an important role in the future electricity supply mix. Currently, crystalline silicon (c-Si) dominates the market with a share of about 90%. Reducing the cost per watt peak and energy pay back time of PV was the major concern of the last decade and remains the main challenge today. For that, thin film silicon solar cells has a strong potential because it allies the strength of c-Si (i.e. durability, abundancy, non toxicity) together with reduced material usage, lower temperature processes and monolithic interconnection. One of the technological key points is the transparent conductive oxide (TCO) used for front contact, barrier layer or intermediate reflector. In this paper, we report on the versatility of ZnO grown by low pressure chemical vapor deposition (ZnO LP-CVD) and its application in thin film silicon solar cells. In particular, we focus on the transparency, the morphology of the textured surface and its effects on the light in-coupling for micromorph tandem cells in both the substrate (n-i-p) and superstrate (p-i-n) configurations. The stabilized efficiencies achieved in Neuchâtel are 11.2% and 9.8% for p-i-n (without ARC) and n-i-p (plastic substrate), respectively.
AIP Conference Proceedings, 2017
Replacing expensive silver with inexpensive copper for the metallization of silicon wafer solar cells can lead to substantial reductions in material costs associated with cell production. A promising approach is the use of multi-wire design. This technology uses many wires in the place of busbars, and the copper wires are "soldered" during the lowtemperature lamination process to the fingers (printed or plated) or to the transparent conductive oxide (TCO) layer, e.g. in the case of the-Si/c-Si heterojunction cells. Here we describe a solar cell design in which wires are attached to TCO layers using transparent conductive polymer (TCP) films. To this end, we have synthesized a number of thermoplastics, poly(arylene ether ketone) copolymers (co-PAEKs), containing phthalide in their main chain. The fraction of phthalidecontaining units in the copolymers was p = 3, 5, 15, and 50 mol %. With increasing p, the peak strain temperature of the co-PAEKs rises from 205 to 290 C and their optical band gap and refractive index increase from 3.12 to 3.15 eV and from 1.6 to 1.614, respectively. The copolymers have a negligible absorption coefficient in the wavelength range 400-1100 nm. When exposed to an excess pressure of 1 atm or above, co-PAEK films less than 30 μm in thickness undergo a transition from a dielectric to a conductive state. The resistivity () of wire/TCP/TCO (ITO = In 2 O 3 :Sn and IFO = In 2 O 3 :F) contacts ranges from 0.37 to 1.43 m cm 2. The polymer with the highest phthalide content (p = 50 mol %) has the lowest. The average work of adhesion per unit area determined by pulling off the wires from the polymer surface depends on both the phthalide content of the co-PAEKs and their reduced viscosity, ranging from 14.3 to 43.5 N/cm. The highest value was obtained for the co-PAEK with p = 50 mol %. We have fabricated low-concentration bifacial IFO/(n + pp +)Cz-Si/ITO solar cells with a wire contact grid attached to IFO and ITO using a co-PAEK film. The efficiency of the best cell under 1× to 7× front/rear illumination was determined to be 18.3-18.9%/15.0-15.6%.
Thin Solid Films, 2016
Boron-doped zinc oxide (BZO) films were grown by metal organic chemical vapor deposition. The influence of B 2 H 6 flow rate and substrate temperature on the microstructure, optical, and electrical properties of BZO films was investigated by X-ray diffraction spectrum, scanning electron microscope, optical transmittance spectrum, and Hall measurements. The BZO films with optical transmittance above 85% in the visible and infrared light range, resistivity of 0.9-1.0 × 10 −3 Ω cm, mobility of 16.5-25.5 cm 2 /Vs, and carrier concentration of 2.2-2.7 × 10 20 cm −3 were deposited under optimized conditions. The optimum BZO films were applied on the bifacial BZO/p-type a-Si:H/itype a-Si:H/n-type c-Si/i-type a-Si:H/n +-type a-Si:H/BZO heterojunction solar cell as both front and back transparent electrodes. Meanwhile, the bifacial heterojunction solar cell with indium tin oxide (ITO) as both front and back transparent electrodes was fabricated. The efficiencies of 17.788% (open-circuit voltage: 0.628 V, short-circuit current density: 41.756 mA/cm 2 and fill factor: 0.678) and 16.443% (open-circuit voltage: 0.590 V, short-circuit current density: 36.515 mA/cm 2 and fill factor: 0.762) were obtained on the a-Si/c-Si heterojunction solar cell with BZO and ITO transparent electrodes, respectively.
In order to compensate the insufficient conductance of heterojunction thin films, transparent conductive oxides (TCO) have been used for decades in both-sides contacted crystalline silicon heterojunction (SHJ) solar cells to provide lateral conduction for efficient carrier collection. In this work, we substitute the TCO layers by utilizing the lateral conduction of c-Si absorber, thereby enabling a TCO-free design. A series resistance of 0.32 Ωcm2 and a fill factor of 80.7% were measured for a TCO-free back-junction SHJ solar cell with a conventional finger pitch of 1.8 mm, thereby proving that relying on lateral conduction in the c-Si bulk is compatible with low series resistances. Achieving high efficiencies in SHJ solar cells with TCO-free front contacts requires suppressing deterioration of the passivation quality induced by direct metal-a-Si:H contacts and in-diffusion of metal into the a-Si:H layer. We show that an ozone treatment at the a-Si:H/metal interface suppresses the m...
AIP Conference Proceedings, 2018
We present high efficiency Ag-free low concentration indium-fluorine-oxide (IFO)/(n + pp +)Cz-Si/Al solar cells based on: (i) a shallow phosphorus-doped n +-emitter; (ii) an easy-to-fabricate screen-printed Al-alloyed Al-p + backsurface-field (BSF); (iiii) transparent conductive IFO film grown by ultrasonic spray pyrolysis, which acts as passivating and antireflection electrode; (iv) Ag-free multi-wire metallization of copper wire attached by the low temperature lamination method simultaneously to the front IFO film, rear Al layer as well as to the interconnecting ribbons arranged outside the structure using transparent conductive polymer (TCP) films. The Al-p + BSF was alloyed in a conveyor belt furnace. Peak firing temperature was varied in the range 820-940 °C. The highest results were obtained for the solar cells with Al-p + BSF alloyed at 860 °C: in the operating range 1-12 suns, their efficiency varies from 18.3 to 19.2%.
Environmental Progress & Sustainable Energy, 2018
Inclusion of ZnO-based transparent conducting oxide (TCO) film layer into amorphous silicon/crystalline silicon (a-Si/c-Si) solar cell enhances its photovoltaic conversion efficiency. These findings have been confirmed here, using Afors HIT software. The simulation study is performed onto a solar cell that was originally lab prepared so as to use its measured parameters in the simulation. The ZnO-based TCO films were electrodeposited on n-type (100) silicon wafer and were simulated. X-ray diffraction (XRD) pattern confirms the zinc blende nature of the TCO layer, and show that the preferred orientation of ZnO films is (002). Scanning electron microscopic (SEM) imaging confirms nano-size nature of the ZnO based TCO film. For comparison purposes, cells with and without TCO layers are investigated by simulating photo-current versus applied potential (J-V) plots. Values of fill factor (FF), short circuit current density (J sc) open circuit potential (V CO) and conversion efficiency (η) are extracted. The energy band diagram, current density and charge carrier generation/recombination phenomena are in-depth analyzed to understand the mechanism of enhancement in the hetero-junction cell performance. Values of quantum efficiency (QE) are also simulated. The results show that the solar cell heterojunction is hypersensitive to the ZnO layer. The added value of using the ZnO-based transparent conductive oxide (TCO) layer, in enhancing intrinsic thin layer (HIT) solar cell conversion efficiency, is assessed by critically comparing it with a control cell having no ZnO layer.
High efficiency screen printed bifacial solar cells on monocrystalline CZ silicon
We present industrialized bifacial solar cells on large area (149 cm 2 ) 2 cm CZ monocrystalline silicon wafers processed with industrially relevant techniques such as liquid source BBr 3 and POCl 3 open-tube furnace diffusions, plasma enhanced chemical vapor deposition (PECVD) SiN x deposition, and screen printed contacts. The fundamental analysis of the paste using at boron-diffused surface and the bifacial solar cell firing cycle has been investigated. The resulting solar cells have front and rear efficiencies of 16.6 and 12.8%, respectively. The ratio of the rear J SC to front J SC is 76.8%. It increases the bifacial power by 15.4% over a conventional solar cell at 20% of 1-sun rear illumination, which equals to the power of a conventional solar cell with 19.2% efficiency. We also present a bifacial glass-glass photovoltaic (PV) module with 30 bifacial cells with the electrical characteristics.