Toward 20% Efficiency With a-Si // poly-Si Tandem Solar Cell

Yoshimi, Masashi; Ma, Wen; Horiuchi, T.; Lim, C.C.; De, S.C.; Hattori, Kiminori; Okamoto, H.; Hamakawa, Yoshihiro

doi:10.1557/proc-258-845

Cited by 6 publications

(1 citation statement)

References 8 publications

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“…which can be absorbed in the active material of device, drastic increase in the efficiency will not be expected for a-Si devices with a-Si active layer of the band gap in the range of 1.7-1. 8 eV. According to the theoretical calculation, the available efficiency of a-Si solar cell is only around up to 14-15% level [2].…”

Section: Introductionmentioning

confidence: 96%

An optimum design of a a-Sipoly-Si tandem solar cell

Horiuchi

Lim

et al.

Conference Record of the Twenty Third IEEE Photovoltaic Specialists Conference - 1993 (Cat. No.93CH3283-9)

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A systematic investigations on high efficiency a-Si //poly-Si four-texminal structure tandem solar cell has been made both on theoretical and experimental approaches. It has been shown from an optimum design theory made on a realistic attainable best efficiency that the best combinations of tandem solar cell is a-Si / poly-Si silicon materials in its high achievable efficiency. In the optical design rule, priority of the photon utilization put on the poly-Si bottom cell. Employing high conductivity with wide optical band gap p type pc-Sic as a window material, n type IC-Si as back ohmic contact with BSF treatment. the conversion efficiency of 17.2% has been obtained for the poly-Si cell. An optimum design of the a-Si top cell has been experimentally made on p pc-Sic/ p a-SiC/i a-Si/n pc-Si/ITO structure, and an efficiency of 7.25% has been obtained with IOonm thick i-layer top cell. While the best efficiency of p-i-n single-junction solar cell with this structure is 12.3% so far with 5 h i-layer thickness deviced by Ag back electrode. With the IOOnm thick ultra thin top cell, a total conversion efficiency of a-Si // poly-Si fourterminal tandem solar cell as high as 21 .O% has been achieved.

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Section: Introductionmentioning

confidence: 96%

An optimum design of a a-Sipoly-Si tandem solar cell

Horiuchi

Lim

et al.

Conference Record of the Twenty Third IEEE Photovoltaic Specialists Conference - 1993 (Cat. No.93CH3283-9)

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Amorphous and microcrystalline silicon films deposited by hot-wire chemical vapor deposition at filament temperatures between 1500 and 1900 °C

Brogueira

Conde

Arekat

et al. 1996

Journal of Applied Physics

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The optical, electronic and structural properties of thin films deposited by Hot-wire chemical vapor deposition with filament temperatures, Tfil, between 1500 and 1900 °C from silane and hydrogen are studied. The substrate temperature, Tsub, was kept constant at 220 °C. Amorphous silicon films (a-Si:H) are obtained at high filament temperatures, low deposition pressures and low hydrogen-to-silane flow rate ratio (Tfil∼1900 °C, p<30 mTorr and FH2/FSiH4≤1). At these deposition conditions, high growth rates are observed (rd≥10 Ås−1) both with and without hydrogen dilution, and no silicon deposition was observed on the filaments. However, if a lower filament temperature is used (Tfil∼1500 °C) a transition from a-Si:H to microcrystalline silicon (μc-Si:H) occurs as the pressure is decreased from above 0.3 Torr to below 0.1 Torr. The highest dark conductivity and lowest activation energy, of ∼1 Scm−1 and <0.1 eV, respectively, were observed for μc-Si:H deposited at p∼50 mTorr. In this Tfil regime, μc-Si:H growth is achieved without hydrogen dilution, for substrate temperatures as low as ∼150 °C, and for very thin films (∼0.05 μm). Silicon growth on the filaments is observed. For both Tfil regimes, an amorphous to microcrystalline transition is also observed when the hydrogen dilution is increased (FH2/FSiH4≳4). A kinetic growth model is developed, which suggests that the transition from amorphous to microcrystalline can be explained by considering a balance between the concentration of atomic hydrogen and the concentration of the precursor to silicon deposition (SixHz with z≤3x) near the sample. This concentration ratio is shown to be controlled both by the deposition pressure, p, and the filament temperature, Tfil.

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Key issues for the efficiency improvement of silicon basis stacked solar cells

Hamakawa¹,

Takakura²

Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036)

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Toward 20% Efficiency With a-Si // poly-Si Tandem Solar Cell

Cited by 6 publications

References 8 publications

An optimum design of a a-Sipoly-Si tandem solar cell

An optimum design of a a-Sipoly-Si tandem solar cell

Amorphous and microcrystalline silicon films deposited by hot-wire chemical vapor deposition at filament temperatures between 1500 and 1900 °C

Key issues for the efficiency improvement of silicon basis stacked solar cells

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