Oriented Perovskite Growth Regulation Enables Sensitive Broadband Detection and Imaging of Polarized Photons Covering 300-1050 nm.
basic_science · Level V
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- Also identified by DOI 10.1002/adma.202003852.
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Abstract
Photodetectors selective to the polarization empower breakthroughs in sensing technology for target identification. However, the realization of polarization-sensitive photodetectors based on intrinsically anisotropic crystal structure or extrinsically anisotropic device pattern requires complicated epitaxy and etching processes, which limit scalable production and application. Here, solution-processed PEA<sub>2</sub> MA<sub>4</sub> (Sn<sub>0.5</sub> Pb<sub>0.5</sub> )<sub>5</sub> I<sub>16</sub> (PEA= phenylethylammonium, MA= methylammonium) polycrystalline film is probed as photoactive layer toward sensing polarized photon from 300 to 1050 nm. The growth of the PEA<sub>2</sub> MA<sub>4</sub> (Sn<sub>0.5</sub> Pb<sub>0.5</sub> )<sub>5</sub> I<sub>16</sub> crystal occurs in confined crystallographic orientation of the (202) facet upon the assistance of NH<sub>4</sub> SCN and NH<sub>4</sub> Cl, enhancing anisotropic photoelectric properties. Therefore, the photodetector achieves a polarization ratio of 0.41 and dichroism ratio (I<sub>max</sub> /I<sub>min</sub> ) of 2.4 at 900 nm. At 520 nm, the I<sub>max</sub> /I<sub>min</sub> even surpasses the one of the perovskite crystalline films, 1.8 and ≈1.2, respectively. It is worth noting that the superior figure-of-merits possess a response width of 900 kHz, I<sub>on</sub> /I<sub>off</sub> ratio of ≈3 × 10<sup>8</sup> , linear dynamic range from 0.15 nW to 12 mW, noise current of 8.28 × 10<sup>-13</sup> A × Hz<sup>-0.5</sup> , and specific detectivity of 1.53 × 10<sup>12</sup> Jones, which demonstrate high resolution and high speed for weak signal sensing and imaging. The proof of concept in polarized imaging confirms that the polarization-sensitive photodetector meets the requirements for practical application in target recognition.