Transparent hole-collecting and buffer layers for heterojunction solar cells based on n-type-doped silicon

Menchini, Francesca; Serenelli, L.; Martini, Luca; Izzi, M.; Stracci, G.; Mangiapane, P.; Salza, E.; Tucci, M.

doi:10.1007/s00339-018-1903-z

Cited by 15 publications

(12 citation statements)

References 48 publications

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“…By contrast, the PCE and FF values of the devices using MoO 3 are reduced with a rise in annealing temperature, indicating the thermal instability of the MoO 3 /Ag contact structure above 100 °C due to the chemical sensitivity of MoO x . 23,31,32 Additionally, the PCE and FF of the p-Si solar cells with a CuI rear contact before and after thermal…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Conductive Cuprous Iodide Hole-Selective Contacts with Thermal and Ambient Stability for Silicon Solar Cells

Lin

Xie

et al. 2018

ACS Appl. Mater. Interfaces

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Dopant-free carrier-selective contacts are becoming increasingly attractive for application in silicon solar cells because of the depositions for their fabrication being simpler and occurring at lower temperatures. However, these contacts are limited by poor thermal and environmental stability. In this contribution, the use of the conductive high work function of cuprous iodide, with its characteristic thermal and ambient stability, has enabled a hole-selective contact for p-type silicon solar cells because of the large conduction band offset and small valence offset at the CuI/p-Si interface. The contact resistivity (≈30 mΩ•cm 2 ) of the Ag/CuI (20 nm)/p-Si contact after annealing to 200 °C represents the CuI-based hole-selective contact with low resistance and high thermal stability. Microscopic images and elemental mapping of the Ag/CuI/p-Si contact interface revealed that a nonuniform, continuous CuI layer separates the Ag electrode and p-type Si. Thermal treatment at 200 °C results in the intermixing of the Ag and CuI layers. As a result, the 200 °C thermal process improves the efficiency (20.7%) and stability of the p-Si solar cells featuring partial CuI hole-selective contact. Furthermore, the devices employing the CuI/Ag contact are thermally stable upon annealing to temperatures up to 350 °C. These results not only demonstrate the use of metal iodide instead of metal oxides as hole-selective contacts for efficient silicon solar cells but also have important implications regarding industrial feasibility and longevity for deployment in the field.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Conductive Cuprous Iodide Hole-Selective Contacts with Thermal and Ambient Stability for Silicon Solar Cells

Lin

Xie

et al. 2018

ACS Appl. Mater. Interfaces

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“…To reduce the undesired effect of parasitic absorption of the emitter and buffer layer at the HJ cell front side, one approach could be the reduction of both thicknesses. However, as widely known, the buffer layer cannot be reduced below 5 nm to avoid the reduction of crystalline silicon surface passivation . Instead, the effect of emitter thickness reduction on the cell FF is evident from the data reported in Figure .…”

Section: Numerical Simulations Of Hj Solar Cellsmentioning

confidence: 89%

“…Most of the intrinsic properties of any material used in the device simulations, such as E g , μ, χ, optical absorptions, and refractive indexes, are deduced from experimental measurements and are listed in Table 2. In Figure 2, the absorption coefficients and the refractive indexes of the materials used in the numerical simulations (c-Si, a-Si:H, and SiOx:H deposited as described in another work 14 ) are deduced from reflectance and transmittance spectroscopy and ellipsometric measurements, respectively, and then compared. To focus the numerical simulations on the solar cell FF, a top-down approach is used, starting from an optimal solar cell with efficiency very close to the physical limit achievable with the a-Si:…”

Section: Numerical Simulations Of Hj Solar Cellsmentioning

confidence: 99%

Silicon heterojunction solar cells toward higher fill factor

Martini

Serenelli

Menchini

et al. 2020

Progress in Photovoltaics

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One of the most limiting factors in the record conversion efficiency of amorphous/crystalline silicon heterojunction solar cells is the not impressive fill factor value. In this work, with the aid of a numerical model, the ways to enhance the cell fill factor up to 85% are investigated in detail, considering the properties of conventional amorphous‐doped films, wider Energy gap layers, and transparent conductive oxide films. The band alignment among the various materials composing the heterojunction is the key to high efficiency but becomes an issue for the solar cell fill factor, if not well addressed. One of the most interesting outcomes of this work is the evidence of hidden barriers arising between the transparent conductive oxide and both selective contacts, due to the mismatch between their work functions. The measurement of light current‐voltage characteristics performed at low temperature is proposed as a way to identify the presence of these barriers in efficient solar cells that do not possess high fill factor values. Experimental J‐V characteristics compared with numerical simulations demonstrated that the sometimes neglected cell base contact needs instead a more careful consideration. To this aim, a model to predict the presence of a hidden barrier at the base contact that limits the cell fill factor is proposed.

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“…[1][2][3][4][5] Some of them have high optical transparency combined with low electric resistivity, which allows their use as transparent contacts in photoelectric devices. [6][7][8] They are in particular promising for silicon-based solar cells with efficiency up to 22%. [6] Substantial difference in electron work functions between silicon (Si) and most metal oxides (MOs) results in energy band bending, providing an enhanced separation of photogenerated charge carriers at the interface of MO/Si heterostructures.…”

Section: Introductionmentioning

confidence: 99%

“…[6] Substantial difference in electron work functions between silicon (Si) and most metal oxides (MOs) results in energy band bending, providing an enhanced separation of photogenerated charge carriers at the interface of MO/Si heterostructures. It has been already demonstrated for heterostructures with semiconducting oxides such as MoO x , [8][9][10][11][12][13][14] VO x , [15][16][17] WO x , [18,19] NiO x and TiO x , [7,20,21] CuO x , and [22,23] MoS x [24] having bandgaps in the range of 3.0À3.8 eV and electron work functions between 4.5 and 6.5 eV. [24] Meanwhile, mechanisms of the charge carrier separation at the MO/Si interfaces and subsequent carrier transport through the MO layers have not been analyzed in detail.…”

Section: Introductionmentioning

confidence: 99%

An Enhanced Charge Carrier Separation in a Heterojunction Solar Cell with a Metal Oxide

Danilyuk

Sidorova

Борисенко

et al. 2021

Physica Status Solidi (a)

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A model of charge carrier transport in heterojunction solar cells composed of a solar light‐absorbing semiconductor and a wide‐bandgap semiconducting metal oxide is proposed. It describes an electric field in the semiconductor originating from the difference in the electron work functions between the two contacting materials, an enhanced hole separation by this field, and subsequent trap‐assisted tunneling of holes through the semiconducting oxide. The model predicts a dramatic influence of the donor concentration in the semiconductor, trap parameters in the oxide, and ideality factor of the semiconductor/oxide heterojunction on the performance of the cell. The efficiency of the solar energy harvesting by MoO x /n‐Si solar cells is calculated to reach 23% of the donor concentration in Si of 1018 cm−3 at a limited hole current density. It is predicted to be reduced to 16−18% when donor concentration is in the range of 1015−1016 cm−3. The numerical predictions agree well with experimental data, at least for donor concentrations in Si below 1018 cm−3, confirming suitability of the model for heterojunction solar cells composed of other semiconductors and semiconducting metal oxides.

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Transparent hole-collecting and buffer layers for heterojunction solar cells based on n-type-doped silicon

Cited by 15 publications

References 48 publications

Conductive Cuprous Iodide Hole-Selective Contacts with Thermal and Ambient Stability for Silicon Solar Cells

Conductive Cuprous Iodide Hole-Selective Contacts with Thermal and Ambient Stability for Silicon Solar Cells

Silicon heterojunction solar cells toward higher fill factor

An Enhanced Charge Carrier Separation in a Heterojunction Solar Cell with a Metal Oxide

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