Thin-film microcrystalline silicon solar cells: 11.9% efficiency and beyond

Sai, Hitoshi; Matsui, Takuya; Kumagai, Hideo; Matsubara, Koji

doi:10.7567/apex.11.022301

Cited by 46 publications

(35 citation statements)

References 37 publications

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“…Such efficiency is considered high when compared to the low-cost solar cells, such as thin film solar cell. Thus, the npn structure performance is better than and dominating thin film solar cell [36][37][38], taking into consideration that the npn structure is not suffering from toxicity issues and practical usage limitations, like most of thin film solar cells. When comparing the npn solar cell microstructure with the c-Si based solar cells, its efficiency is lower than such cells.…”

Section: The Effect Of P + Base Doping Variation On the Npn Micromentioning

confidence: 99%

Investigation of Base High Doping Impact on the npn Solar Cell Microstructure Performance Using Physically Based Analytical Model

2021

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Recently, there is a rapid trend to incorporate low cost solar cells in photovoltaic technology. In this regard, low-cost high-doped Silicon wafers are beneficial; however, the high doping effects encountered in these wafers render their practical use in fabrication. The npn solar cell microstructure has been found to avoid this issue by the proper design of vertical generation and lateral collection of the light generated carriers. We report on the impact of the p + base doping concentration, up to 2×10 19 cm-3 , on the npn microstructure performance to find the most appropriate way for high efficiency. To optimize the structure, a series of design steps has been applied using our previously published analytical model. Before inspecting the high doped base effect, firstly, the n + emitter is optimized. Secondly, the impact of bulk recombination inside the p + base is introduced showing the range of optimum base width (Wp). Then, we investigate thoroughly the impact of base doping levels for different base widths to get the optimum Wp that satisfies maximum efficiency. The results show that for p + base doping concentration ranging from 5×10 17 cm-3 to 2×10 19 cm-3 , the npn microstructure efficiency decreases from 15.9% to 9%, respectively. Although the efficiency is degraded considerably for higher doping levels, the structure still achieves a competitive efficiency at higher doping levels, for which its cost is greatly reduced, in comparison with thin film solar cells. Moreover, using higher doping permits lesser wafer area which could be beneficial for large area solar cells design.

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Section: The Effect Of P + Base Doping Variation On the Npn Micromentioning

confidence: 99%

Investigation of Base High Doping Impact on the npn Solar Cell Microstructure Performance Using Physically Based Analytical Model

2021

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“…Amorphous silicon (a-Si) is a theoretically promising top cell material owing to its suitable bandgap of~1.7 eV when it is stacked with c-Si to made a tandem solar cell [45]. However, only a few studies have focused on a-Si/c-Si tandem devices [31,46,47].…”

Section: A-si As Top Cellmentioning

confidence: 99%

“…The main reason can be attributed to the low PCE of a-Si solar cells. Although a a-Si photovoltaic device has been developed since the 1970s, its record efficiency of 10.2% is still much lower than other mainstream solar cells, such as multi-Si, mono-Si, and CdTe solar cells [7,45]. The current device performance of the a-Si solar cell is lower than the requirement for the top cell of Si-based tandems to compensate for the efficiency loss [12].…”

Section: A-si As Top Cellmentioning

confidence: 99%

Possible top cells for next-generation Si-based tandem solar cells

Chen

Tang

2020

Front. Optoelectron.

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Si-based solar cells, which have the advantages of high efficiency, low manufacturing costs, and outstanding stability, are dominant in the photovoltaic market. Currently, state-of-the-art Si-based solar cells are approaching the practical limit of efficiency. Constructing Si-based tandem solar cells is one available pathway to break the theoretical efficiency limit of single-junction silicon solar cells. Various top cells have been explored recently in the construction of Si-based tandem devices. Nevertheless, many challenges still stand in the way of extensive commercial application of Si-based tandem solar cells. Herein, we summarize the recent progress of representative Si-based tandem solar cells with different top cells, such as III-V solar cells, wide-bandgap perovskite solar cells, cadmium telluride (CdTe)-related solar cells, Cu(In,Ga)(Se,S) 2 (CIGS)-related solar cells, and amorphous silicon (a-Si) solar cells, and we analyze the main bottlenecks for their next steps of development. Subsequently, we suggest several potential candidate top cells for Si-based tandem devices, such as Sb 2 S 3 , Se, CdSe, and Cu 2 O. These materials have great potential for the development of high-performance and low-cost Si-based tandem solar cells in the future.

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“…In contrast to hydrogenated amorphous silicon (a-Si:H), hydrogenated microcrystalline (or nanocrystalline) silicon (µc-Si:H) allows light absorption in the infrared due to its lower band-gap. It also shows better optoelectronic stability under light exposure, and it currently holds the record for a single-junction thin film silicon solar cell [1]. However, limited by the indirect band-gap, it usually requires several microns of µc-Si:H absorber layer to sufficiently absorb the light for single-junction solar cells, and even thicker for multi-junction devices to achieve current matching.…”

Section: Introductionmentioning

confidence: 99%

Microcrystalline silicon thin film deposition from silicon tetrafluoride: Isolating role of ion energy using tailored voltage waveform plasmas

Wang

Daineka

Elyaakoubi

et al. 2019

Solar Energy Materials and Solar Cells

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The energy of ions during plasma enhanced chemical vapor deposition (PECVD) is known to impact material quality, but isolating this effect from other process parameters (plasma density, pressure) in a capacitively coupled plasma (CCP) is not straightforward. In this work, we utilize a novel radio-frequency (RF) excitation technique-tailored voltage waveforms (TVW)-as a solution to achieve ion flux-energy decoupling through the electrical asymmetry effect. This makes it possible to independently study the impact of ion energy on material deposition. We study the impact of ion energy-more precisely the maximum ion bombardment energy (IBEmax) before collisions-on the PECVD of hydrogenated microcrystalline silicon (µc-Si:H) thin films from an SiF4/H2/Ar chemistry. Through structural and electronic analysis, we find that the variation of IBEmax directly translates into material quality, even at relatively high process pressure. Better material properties (crystalline grain features, material density and photoelectronic response) are obtained for films deposited with moderate values of IBEmax around 45-55 eV. Above this range, a deterioration in material quality is observed, presumably due to more effective bulk atomic displacements induced by the silicon-containing ions. These results are consistent with the performance of single-junction µc-Si:H solar cell devices using these materials as active layers. Optimum performance is obtained for devices with an absorber layer deposited using a plasma excitation resulting in IBEmax in the range of ~45-55 eV. The variation in device performance is mainly due to changes in the open circuit voltage.

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Thin-film microcrystalline silicon solar cells: 11.9% efficiency and beyond

Cited by 46 publications

References 37 publications

Investigation of Base High Doping Impact on the npn Solar Cell Microstructure Performance Using Physically Based Analytical Model

Investigation of Base High Doping Impact on the npn Solar Cell Microstructure Performance Using Physically Based Analytical Model

Possible top cells for next-generation Si-based tandem solar cells

Microcrystalline silicon thin film deposition from silicon tetrafluoride: Isolating role of ion energy using tailored voltage waveform plasmas

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