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Bilayer broadband antireflective coating to achieve planar heterojunction perovskite solar cells with 23.9% efficiency

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  • ReceivedJul 4, 2020
  • AcceptedAug 4, 2020
  • PublishedOct 22, 2020

Abstract

Although perovskite solar cells (PSCs) have achieved encouraging efficiency, the photon loss at the substrate due to light reflection has not been well addressed. Light management is promising to reduce reflection loss and realize higher power conversion efficiency (PCE) of PSCs. Here, a bilayer antireflective coating (ARC) has been designed and coated onto the backside of the glass substrate of (FAPbI3)x-(MAPbBr3)1−x PSCs to enhance photon harvesting and consequently the device efficiency. The bottom layer of the bilayer ARC is made from a silica polymer and the top layer is made from the mixture of hexamethyldisiloxane-modified mesoporous silica nanoparticles and a fluorinated silica polymer. By adjusting the refractive index and the film thickness of each layer according to a two-layer model, enhanced glass transmittance in a broadband wavelength range can be reached, with the maximum transmittance increasing from ca. 90% to over 95%. With the bilayer ARC, the maximum short-circuit current density and PCE of (FAPbI3)x(MAPbBr3)1−x PSCs can be increased from 25.5 mA cm−2 and 22.7% to 26.5 mA cm−2 and 23.9% with negligible changes in fill factor and open-circuit voltage. This work presents a simple yet effective strategy to enhance the efficiency of solar cells employing bilayer antirefective coatings, which can be applied to other types of solar cells.


Funded by

the Natural Science Foundation of Hubei Province(2019CFB575)

and the National Natural Science Foundation of China(51861145101)


Interest statement

The authors declare no competing interest.


Contributions statement

Wang Y synthesized and prepared the ARC coating. Wang H, Chen M and Wang P fabricated the solar cell devices. Mao Y and Han W characterized the film morphology. Liu D and Wang T conceived the idea. All authors discussed the results and approved the manuscript.


Author information

Yalun Wang received his BE degree in materials science and engineering from Hubei University, China in 2017. He is currently a Master student under the supervision of Dr. Dan Liu at Wuhan University of Technology, and is working on functional coatings to improve the efficiency and lifetime of solar cells.


Hui Wang received her BE degree in materials science and engineering from Wuhan University of Technology, China in 2018. She is currently a PhD student under the supervision of Prof. Tao Wang at Wuhan University of Technology, and is working on perovskite solar cells.


Dan Liu received her PhD in physics from the University of Surrey, U.K. in 2010. She was a postdoc research associate at the School of Physics and Astronomy, University of Leeds, UK before joining as an associate professor in 2014 in the School of Materials Science and Engineering, Wuhan University of Technology, China. Her research interests are functional thin films for optoelectronic devices.


Supplement

Acknowledgements

This work was supported by the Natural Science Foundation of Hubei Province (2019CFB575), and the National Natural Science Foundation of China (51861145101).


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  • Figure 1

    The synthesis routes of (a) HMDS-MSNs, (b) silica polymer and (c) fluorinated silica polymer, and (d) the device architecture of the PSCs coated with the bilayer ARC.

  • Figure 2

    SPM images of the (a) ARC1 layer, (b) ARC2 layer coated on glass and (c) ARC2 layer coated on ARC1. SPM image sizes are 5 μm × 5 μm. SEM images of (d) ARC1 layer and (e) ARC2 layer coated on ARC1. The insets in (d) and (e) show the water contact angle images of ARC1 and ARC2 coated on ARC1.

  • Figure 3

    (a) Transmittance and (b) reflectance of the glass, glass coated with the single-layer ARC2 and bilayer ARC. (c) Transmittance of the fresh bilayer ARC and that after 3 month aging.

  • Figure 4

    (a) J-V curves and EQE spectra of the (FAPbI3)x(MAPbBr3)1−x PSCs coated with and without the bilayer ARC. (c) PCE, (d) JSC, (e) FF and (f) VOC of all eight pixels of a (FAPbI3)x(MAPbBr3)1−x PSC with and without the bilayer ARC.

  • Table 1   The modeling factors and values

    Modeling Factors

    Values

    Reference wavelength (nm)

    550

    Illuminant

    White

    Incident angle (°)

    0.0

    Incident medium

    Air

    Substrate

    Glass

    Thickness (mm)

    1.0

    Exit medium

    Air

    Detector

    Ideal

    First surface

    Front

  • Table 2   Device metrics of the PSCs with and without the bilayer ARC

    JSC

    (mA cm−2)

    Calculated JSC (mA cm−2)

    FF (%)

    VOC (V)

    PCE (%)

    (FAPbI3)x(MAPbBr3)1−x (W/O ARC)

    25.5 (25.3±0.3)

    23.7

    80.5 (75.8±4.1)

    1.11 (1.07±0.04)

    22.7 (20.5±1.6)

    (FAPbI3)x(MAPbBr3)1−x (with bilayer ARC)

    26.5 (26.3±0.3)

    24.8

    80.5 (76.2±3.8)

    1.12 (1.07±0.04)

    23.9 (21.6±1.6)

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