Research ArticleAPPLIED OPTICS

Wafer-scale growth of large arrays of perovskite microplate crystals for functional electronics and optoelectronics

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Science Advances  02 Oct 2015:
Vol. 1, no. 9, e1500613
DOI: 10.1126/sciadv.1500613
  • Fig. 1 Schematic illustration of the patterned growth of regular arrays of perovskite microplate crystals.

    (A) Schematic illustration of the procedure for preparing methylammonium lead iodide perovskite plates on a patterned substrate. The SiO2/Si substrate was first functionalized with self-assembled monolayers of OTS to produce a hydrophobic surface and then lithographically patterned to create periodic arrays of hydrophilic areas. A hot aqueous PbI2 solution (0.1 g/100 ml) was used as seeding solution to produce PbI2 seed particles in hydrophilic regions using a flow seeding process. The seeded substrate was next immersed in a saturated PbI2 solution at 80°C to further grow the seeds into larger PbI2 microplates. Finally, PbI2 microplate arrays were intercalated with methylammonium iodide vapor in a homebuilt tube furnace system. (B to D) Optical images of PbI2 seed arrays after flow seeding process (B) and after further growth in saturated PbI2 solution at 80°C for 1 min (C) and for 2 min (D). Scale bars, 40 μm.

  • Fig. 2 Growth of periodic arrays of PbI2 microplate crystals.

    (A) Dark-field optical microscopy image of PbI2 microplates in hexagonal lattice patterns. Scale bar, 200 μm. (B and C) Higher-magnification bright-field optical microscopy images of PbI2 microplates. Scale bars, 40 μm (B) and 20 μm (C). (D) SEM image of PbI2 microplates in a hexagonal lattice pattern. Scale bar, 20 μm. (E) Dark-field optical microscopy image of PbI2 plates in square lattice patterns (8 μm × 25 μm). Scale bar, 200 μm. (F and G) Higher-magnification bright-field optical microscopy images of PbI2 microplate arrays. Scale bars, 40 μm (F) and 20 μm (G). (H) SEM image of PbI2 plates in a square lattice pattern. Scale bar, 20 μm. (H to K) Bright-field optical microscopy images of PbI2 microplates in square lattice patterns with periodicities of 20, 30, and 40 μm, respectively. Scale bars, 20 μm. (L) Dark-field optical microscopy image (top) and SEM image (bottom) of PbI2 microplates arranged in “UCLA” patterns. Scale bar, 100 μm. (M) Digital photo of patterned growth on a 4-inch silicon wafer. (N) XRD pattern of PbI2 microplate arrays on a glass substrate. (O) Low-resolution TEM image of a PbI2 microplate. Scale bar, 2 μm. (Inset) Electron diffraction pattern. (P) HRTEM image of the PbI2 microplate with lattice fringes clearly resolved. Scale bar, 2 nm.

  • Fig. 3 Conversion of PbI2 microplates into high-quality perovskite crystals.

    (A) Schematic illustration of the change in lattice structure from layered PbI2 to tetragonal perovskite after methylammonium iodide intercalation. (B) Dark-field optical microscopy image of perovskite microplate arrays. Scale bar, 200 μm. (C) Higher-magnification bright-field optical microscopy image of perovskite microplate arrays. Scale bar, 20 μm. (D) SEM image of perovskite arrays. Scale bar, 20 μm. (E) XRD pattern of converted perovskite microplates on a glass substrate. (F) Low-resolution TEM image of a perovskite microplate. Scale bar, 2 μm. (Inset) Electron diffraction pattern of the microplate. (G) HRTEM image of a perovskite microplate with clearly resolved lattice fringes. Scale bar, 2 nm. (H) UV-vis absorption and photoluminescence (PL) spectra of PbI2 and perovskite microplates. (I) Spatially resolved mapping image of the photoluminescence of a perovskite crystal array. Scale bar, 20 μm.

  • Fig. 4 Selective growth of perovskite crystals on prepatterned electrodes for photodetector arrays and FETs.

    (A) Optical microscopy image of perovskite microplate crystals bridging prepatterned arrays of electrode pairs. Scale bar, 200 μm. (B) Typical I-V curve of a perovskite crystal under dark and light illumination. (Inset) Optical microscopy image of a perovskite crystal bridging two gold electrodes. The distance between the electrode pair is 8 μm. Scale bar, 20 μm. (C) Photocurrent versus incident light power of a typical device (source-drain voltage, 5 V). (Inset) Response speed of a typical two-probe device (laser illumination, 488 nm; power, 1.2 nW; source-drain voltage, 5 V). (D) Optical image of photodetector arrays with a U-shaped mask (U-shaped transparent area). (E) Schematic illustration of the device arrangement of photodetector arrays with a U-shaped mask under blue LED illumination (wavelength, 463 nm; power density, 600 μW/cm2). Red dots, devices with photocurrent; gray dots, devices without photocurrent. (F) Photocurrent mapping of photodetector arrays with a U-shaped mask under blue LED illumination. (G and H) Output (Vg = 0, 20, 40, 60, and 80 V) (G) and transfer (Vsd = 10, 15, 20, and 25 V) (H) characteristics of FET based on a perovskite microplate crystal at 77 K. (I) Distribution of the field effect electron mobility of 27 perovskite microplate transistors measured at 77 K. Red, mobility derived from backward sweep; blue, mobility derived from forward sweep.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/1/9/e1500613/DC1

    Fig. S1. SEM characterization of seeded substrate using a flow seeding process.

    Fig. S2. Optical microscopy image of PbI2 plates grown on a transparent glass substrate.

    Fig. S3. EDX studies of prepared perovskite plates.

    Fig. S4. Digital image of perovskite photodetector arrays on a transparent glass substrate.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. SEM characterization of seeded substrate using a flow seeding process.
    • Fig. S2. Optical microscopy image of PbI2 plates grown on a transparent glass substrate.
    • Fig. S3. EDX studies of prepared perovskite plates.
    • Fig. S4. Digital image of perovskite photodetector arrays on a transparent glass substrate.

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