Tailoring of a visible-light-absorbing biaxial ferroelectric towards broadband self-driven photodetection.

Han, Shiguo; Li, Maofan; Liu, Yi; Guo, Wuqian; Hong, Mao-Chun; Sun, Zhihua; Luo, Junhua · Nat Commun · 2021

basic_science · Level V

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Abstract

In terms of strong light-polarization coupling, ferroelectric materials with bulk photovoltaic effects afford a promising avenue for optoelectronic devices. However, due to severe polarization deterioration caused by leakage current of photoexcited carriers, most of ferroelectrics are merely capable of absorbing 8-20% of visible-light spectra. Ferroelectrics with the narrow bandgap (<2.0 eV) are still scarce, hindering their practical applications. Here, we present a lead-iodide hybrid biaxial ferroelectric, (isopentylammonium)<sub>2</sub>(ethylammonium)<sub>2</sub>Pb<sub>3</sub>I<sub>10</sub>, which shows large spontaneous polarization (~5.2 μC/cm<sup>2</sup>) and a narrow direct bandgap (~1.80 eV). Particularly, the symmetry breaking of 4/mmmFmm2 species results in its biaxial attributes, which has four equivalent polar directions. Accordingly, exceptional in-plane photovoltaic effects are exploited along the crystallographic [001] and [010] axes directions inside the crystallographic bc-plane. The coupling between ferroelectricity and photovoltaic effects endows great possibility toward self-driven photodetection. This study sheds light on future optoelectronic device applications.