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. 2019 Dec 11;11(49):45586-45595.
doi: 10.1021/acsami.9b14709. Epub 2019 Nov 22.

High-Mobility Hydrogenated Fluorine-Doped Indium Oxide Film for Passivating Contacts c-Si Solar Cells

Can Han  1   2   3 , Luana Mazzarella  1 , Yifeng Zhao  1 , Guangtao Yang  1 , Paul Procel  1 , Martijn Tijssen  1 , Ana Montes  1 , Luca Spitaleri  4 , Antonino Gulino  4 , Xiaodan Zhang  2 , Olindo Isabella  1 , Miro Zeman  1
Affiliations

High-Mobility Hydrogenated Fluorine-Doped Indium Oxide Film for Passivating Contacts c-Si Solar Cells

Can Han et al. ACS Appl Mater Interfaces. .

Erratum in

Abstract

Broadband transparent conductive oxide layers with high electron mobility (μe) are essential to further enhance crystalline silicon (c-Si) solar cell performances. Although metallic cation-doped In2O3 thin films with high μe (>60 cm2 V-1 s-1) have been extensively investigated, the research regarding anion doping is still under development. In particular, fluorine-doped indium oxide (IFO) shows promising optoelectrical properties; however, they have not been tested on c-Si solar cells with passivating contacts. Here, we investigate the properties of hydrogenated IFO (IFO:H) films processed at low substrate temperature and power density by varying the water vapor pressure during deposition. The optimized IFO:H shows a remarkably high μe of 87 cm2 V-1 s-1, a carrier density of 1.2 × 1020 cm-3, and resistivity of 6.2 × 10-4 Ω cm. Then, we analyzed the compositional, structural, and optoelectrical properties of the optimal IFO:H film. The high quality of the layer was confirmed by the low Urbach energy of 197 meV, compared to 444 meV obtained on the reference indium tin oxide. We implemented IFO:H into different front/back-contacted solar cells with passivating contacts processed at high and low temperatures, obtaining a significant short-circuit current gain of 1.53 mA cm-2. The best solar cell shows a conversion efficiency of 21.1%.

Keywords: electron mobility; hydrogenated fluorine-doped indium oxide (IFO:H); passivating contacts; silicon heterojunction (SHJ); transparent conductive oxide (TCO).

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Sketches of (a) TLM samples (picture inset) and (b) solar cell structures (poly-Si(Cx) hybrid on the left-hand side, SHJ on the right-hand side). SP Ag stands for screen-printed silver.
Figure 2
Figure 2
Resistivity (ρ), carrier density (Ne), and Hall mobility (μe) of the as-grown In2O3-based films as a function of variable H2O vapor pressure.
Figure 3
Figure 3
(a) XPS wide scan with an inset of In 3d core-level XPS spectra, (b) O 1s, and (c) F 1s core-level XPS spectra of the as-sputtered IFO:H film. The scatter plots in red color represent the experimental profiles, and the solid lines refer to the Gaussian components.
Figure 4
Figure 4
(a) FTIR spectra of the IFO:H and IFO films. (b) X-ray diffraction patterns for the optimized IFO:H film.
Figure 5
Figure 5
(a) AFM micrograph of the optimal IFO:H film. (b) Cross-sectional profile along the line in (a).
Figure 6
Figure 6
Optical properties of the IFO:H and ITO films. (a) Transmittance and reflectance spectra, (b) calculated absorption coefficient curves, (c) optical band gap plot curves, and (d) the wavelength-dependent refractive index (n) and extinction coefficient (k) curves.
Figure 7
Figure 7
External quantum efficiency (EQE) curves of (a) poly-SiCx hybrid, (b) poly-Si hybrid, and (c) SHJ solar cells, respectively. Jsc_EQE were provided accordingly.
Figure 8
Figure 8
(a) Fill factor (FF) of different types of solar cells with IFO:H applied on the n-contact stack at the rear sides of poly-Si(Cx) hybrid, and on both sides of SHJ solar cells, compared to ITO-based devices as references. Results from different metal coverages are provided. (b) Implied Voc variation with TCOs’ sputtering processes based on four series of experimental data, and (c) current–voltage characteristics of the best SHJ solar cells integrating double-side IFO:H films.
See this image and copyright information in PMC

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