Remarkable progress in thin-film silicon solar cells using high-efficiency triple-junction technology (original) (raw)
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Development of Hetero-Junction Silicon Solar Cells with Intrinsic Thin Layer: A Review
Coatings
This paper presents the history of the development of heterojunction silicon solar cells from the first studies of the amorphous silicon/crystalline silicon junction to the creation of HJT solar cells with novel structure and contact grid designs. In addition to explanation of the current advances in the field of research of this type of solar cells, the purpose of this paper is to show possible ways to improve the structure of the amorphous silicon/crystalline silicon-based solar cells for further improvement of the optical and electrical parameters of the devices by using of numerical simulation method and current hypotheses. This paper briefly describes the history, beginning from the first studies of and research of HJT-structure solar cells. It raises questions about the advantages and existing problems of optimization of HJT solar cells. The authors of this paper are proposing further ways of design development of HJT solar cells.
International Journal of Photoenergy, 2012
The conversion efficiency of a solar cell can substantially be increased by improved material properties and associated designs. At first, this study has adopted AMPS-1D (analysis of microelectronic and photonic structures) simulation technique to design and optimize the cell parameters prior to fabrication, where the optimum design parameters can be validated. Solar cells of single junction based on hydrogenated amorphous silicon (a-Si:H) have been analyzed by using AMPS-1D simulator. The investigation has been made based on important model parameters such as thickness, doping concentrations, bandgap, and operating temperature and so forth. The efficiency of single junction a-Si:H can be achieved as high as over 19% after parametric optimization in the simulation, which might seem unrealistic with presently available technologies. Therefore, the numerically designed and optimized a-SiC:H/a-SiC:H-buffer/a-Si:H/a-Si:H solar cells have been fabricated by using PECVD (plasma-enhanced chemical vapor deposition), where the best initial conversion efficiency of 10.02% has been achieved (V oc = 0.88 V, J sc = 15.57 mA/cm 2 and FF = 0.73) for a small area cell (0.086 cm 2). The quantum efficiency (QE) characteristic shows the cell's better spectral response in the wavelength range of 400 nm-650 nm, which proves it to be a potential candidate as the middle cell in a-Si-based multijunction structures.
2012
In this contribution, we shortly review the main features of amorphous /crystalline silicon heterojunction (SHJ) solar cells, including interface defects and requirements for high quality interfaces. We show how a process flow with a limited number of process steps leads to screen printed solar cells of 2x2cm 2 with 21.8% efficiency and of 10xlOcm 2 with 20.9% efficiency (n-type FZ). We show that the devices work in high injection conditions of 3xl0 15 cm-3 at the maximum power point, a factor two higher than the base doping. Several research labs and companies can now produce large area 6" cells well over 20% on CZ wafers and some of the critical cost factors, such a metallization can be overcome with suitable strategies. Based on the high quality coating tools and processes developed for thin films used for flat panel display or thin film solar cell coatings, the deposition of the layers required to make SHJ cells has the potential to be performed in a controlled way at low cost. Considering the few process steps required, the high quality n type Cz wafers that can be obtained by proper crystal growth control, SHJ technology has several assets that could make it become a widespread PV technology.
Japanese Journal of Applied Physics, 2015
Quadruple junction solar cells and modules are presented, which consist of hydrogenated amorphous (a-Si:H) and microcrystalline silicon (µc-Si:H) in the a-Si:H/a-Si:H/µc-Si:H/µc-Si:H configuration. The highest measured conversion efficiency of a mini-module with an aperture area of 61.44 cm 2 was 13.4% before and 12.0% after more than 1000 h of light soaking, respectively. In this paper, we discuss the advantages of the quadruple junction design over the common tandem design, which is ascribed mainly to the fact that the total absorber thickness can be increased while electronic properties and stability are maintained or even improved. The role of the µc-SiO x :H intermediate reflector is highlighted and an optimization of the doping concentration in this layer is presented. Furthermore, the advantage of the high maximum power voltage for the monolithic cell interconnection laser design of modules is shown.
Solar Energy Materials and Solar Cells, 2010
a b s t r a c t Hydrogenated microcrystalline silicon (mc-Si:H) solar cells show decreasing open-circuit voltage with increasing crystalline volume fraction (F c ). Therefore, most research groups focus on mc-Si:H films produced close to the transition with amorphous silicon. Three cells with varying F c and large-grain fraction, F lg have been studied experimentally and by modeling. The large grained fluorinated mc-Si:H cell appears to be an exception to the above rule, and modeling is used to understand why low and high F c mc-Si:H and mc-Si:F:H are used as the second intrinsic-layer in hypothetical double junction cells.
Dhaka University Journal of Science
In this work, the solar cell design parameters like- layer thickness, bandgap, donor and acceptor concentrations are varied to find optimum structure of a hydrogenated amorphous silicon (a-Si:H) and hydrogenated microcrystalline silicon (μc-Si:H) heterojunction p-i-n solar cell. A thin a-Si:H p-layer of 1 to 5 nm followed by a thick a-Si:H i-layer of thickness 1400 to 1600 nm and then thin n-layer of thickness 1 to 5 nm with acceptor concentration of 102 cm−3 and donor concentration of 1020 cm−3 and the bandgaps of p-, i-, and n- layers with higher bandgaps closer to 2.2 eV for a-Si:H p-layer, 1.85 eV for a-Si:H i-layer, and 1.2 eV for μc-Si:H n-layer have showed better performances. The optimum cell has a JSC of 18.93 mA/cm2, VOC of 1095 mV, Fill factor of 0.7124, and efficiency of 14.77%. The overall external quantum efficiency of the numerically designed cell also remained very high from 85-95 % for wavelengths of 300-650 nm range. This indicates that the device will perform its ...
Physical and Technological Aspects of a-Si:H/c-Si Hetero-Junction Solar Cells
2006
We report on the basic properties of a-Si:H/c-Si heterojunctions, their effects on the recombination of excess carriers and its influence on the a-Si:H/c-Si heterojunction solar cells. For this purpose we measured the gap state density distribution in thin a-Si:H layers, determined its dependence on deposition temperature and doping by an improved version of near UV-photoelectron emission spectroscopy. Furthermore, the Fermi level position in the a-Si:H and the valence band offset were directly measured. In combination with interface specific methods such as surface photovoltage analysis and our numerical simulation program AFORS-HET, we are able to find out the optimum in wafer pretreatment, doping and deposition temperature for efficient a-Si:H/c-Si solar cells without an i-type a-Si:H buffer layer. By a deposition at 210°C with an emitter doping of 2000 ppm of B 2 H 6 on a well cleaned pyramidal structured c-Si(p) wafer we reached 19.8 % certified efficiency.
New developments in amorphous thin-film silicon solar cells
IEEE Transactions on Electron Devices, 1999
Thin-film silicon solar cells usually contain amorphous silicon layers made by plasma enhanced chemical vapor deposition (PECVD). This CVD method has the advantage that large-area devices can be manufactured at a low processing temperature, thus facilitating low-cost solar cells on glass, metal foil, or polymer foil. In order to obtain higher conversion efficiencies while keeping the manufacturing cost low, a new development is to introduce low bandgap materials in a multijunction device structure. A frequently used low bandgap material is amorphous silicon germanium. Record initial efficiencies in excess of 15% have been reported for triple-junction solar cells comprising these alloys. In this paper, we present a novel manufacturing method for amorphous silicon based tandem cells suitable for roll-to-roll production.