Research ArticlePHYSICAL SCIENCE

Anomalous photovoltaic effect in organic-inorganic hybrid perovskite solar cells

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Science Advances  17 Mar 2017:
Vol. 3, no. 3, e1602164
DOI: 10.1126/sciadv.1602164
  • Fig. 1 APV effect in OIHP solar cells.

    (A) Scheme of the lateral perovskite solar cells before (top) and after electrical poling (middle and bottom), where the device structure is Au/MAPbBr3 (or MAPbI3)/Au. Eg, bandgap. (B) I-V curves of the MAPbBr3 devices after different intensities of electrical poling (for example, poling for 1 to 2 min at 0.2, 0.3, 0.8, 2, and 5 V/μm, respectively). (C) I-V curves of the electrically poled (5 V/μm) MAPbBr3 devices with different electrode spacings. (D) Summarized VOC of lateral MAPbBr3 devices with different poling electrical fields and electrode spacings. E-field, electrical field.

  • Fig. 2 Characterizations of the APV effect.

    (A) and (B) show the temperature-dependent photovoltage and photocurrent of the MAPbBr3 device, respectively. (C) Semilogarithmic relationship between the anomalous photovoltage and photocurrent obtained at different light intensities. a.u., arbitrary units. (D) Comparison of the I-V curves of the MAPbBr3 device measured immediately after electrical poling or 1000 s after electrical poling, where the cyan area is defined by the difference between two I-V curves obtained, indicating the contribution from ion back diffusion current. (E) Durable photocurrent output at a bias of 4 V, where the influence of ion diffusion current disappeared quickly in a few hundreds of seconds.

  • Fig. 3 Role of ion accumulation in APV effect.

    (A) Scheme of the KPFM characterization, where the anode of the solar cell was grounded. (B) Surface potential distribution of the MAPbBr3 device measured in the dark and under light (in N2 atmosphere), respectively. (C) Surface potential profiles at the position marked in (B). (D) Scheme of the dispersed tunneling junction in OIHP film, which consists of many discontinuous, randomly distributed tiny tunneling junction regions. Iph, photocurrent. (E) Scheme of the aligned tunneling junction. (F) Broadened GBs in OIHP film by E-beam treatment under SEM (10 to 20 kV), which was used to control the position of ion accumulation. (G) and (H) show the topography and surface potential of the E-beam–treated OIHP film (90 μm × 90 μm) with controlled ion accumulation pattern with “Z” shapes, respectively. (I) Topography (top) and surface potential (bottom) profiles of the position marked in (H).

  • Fig. 4 Oxygen-sensitive APV effect.

    (A) Vanished APV due to oxygen injection, where the electrode spacing of OIHP solar cells was 100 μm. (B) Recovered APV in the same MAPbBr3 device as shown in (A) by pumping oxygen away. (C) Evolution of the photovoltaic against time, where the MAPbBr3 solar cells were exposed to oxygen (100 to 1000 Pa) during the first 45 min and then kept in vacuum from the 46th minute. (D) Topography of the E-beam–patterned MAPbBr3 film, where the measured area was 60 μm × 90 μm. (E) and (F) show the surface potential images of the electrically poled MAPbBr3 film in N2 and air, respectively, where the abrupt potential change vanished because of oxygen absorption. (G) and (H) show the schematic energy diagrams at GBs in N2 and air, respectively, where the ion accumulation–induced tunneling junction vanished because of oxygen absorption. CB, conduction band; VB, valence band.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/3/e1602164/DC1

    fig. S1. APV effect in lateral MAPbI3 solar cells.

    fig. S2. Independence of the APV effect on light polarization directions.

    fig. S3. APV effect in nonpolar CsPbBr3-based lateral perovskite solar cells.

    fig. S4. I-V curves of electrically poled MAPbBr3 lateral solar cells at different temperatures.

    fig. S5. Stabilities of the APV effect under dark and illuminating conditions.

    fig. S6. Accelerated degradation of MAPbBr3 polycrystalline films by illumination and vacuuming.

    fig. S7. Continuously formed over-bandgap VOC in MAPbBr3 solar cells.

    fig. S8. Illustration of the GB broadening process caused by E-beam treatment.

    fig. S9. Illustration of the proposed working mechanism for dispersed tunneling junction–induced APV effect.

    fig. S10. Disappearance of APV effect induced by oxygen absorption.

    table S1. VOC obtained at forward and backward scanning at different temperatures.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. APV effect in lateral MAPbI3 solar cells.
    • fig. S2. Independence of the APV effect on light polarization directions.
    • fig. S3. APV effect in nonpolar CsPbBr3-based lateral perovskite solar cells.
    • fig. S4. I-V curves of electrically poled MAPbBr3 lateral solar cells at different temperatures.
    • fig. S5. Stabilities of the APV effect under dark and illuminating conditions.
    • fig. S6. Accelerated degradation of MAPbBr3 polycrystalline films by illumination and vacuuming.
    • fig. S7. Continuously formed over-bandgap VOC in MAPbBr3 solar cells.
    • fig. S8. Illustration of the GB broadening process caused by E-beam treatment.
    • fig. S9. Illustration of the proposed working mechanism for dispersed tunneling junction–induced APV effect.
    • fig. S10. Disappearance of APV effect induced by oxygen absorption.
    • table S1. VOC obtained at forward and backward scanning at different temperatures.

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