基于二维杂化钙钛矿铁电晶体组装低检测限的超灵敏偏振光探测器

Ultrasensitive polarized-light photodetectors based on 2D hybrid perovskite ferroelectric crystals with a low detection limit

二维(2D)杂化钙钛矿铁电体的自发极化(P_(s))与光耦合作用有利于光生载流子分离,在光电器件方面显示出潜在的应用前景.然而,基于2D杂化钙钛矿铁电体组装的低检测限的偏振光检测器未见报道.本文基于2D杂化钙钛矿铁电体BA_(2)CsPb_(2)Br_(7)(BA为正丁胺)的高质量单晶,组装超灵敏的偏振光探测器.材料独特的双层钙钛矿结构产生较强的光学各向异性,沿不同晶轴方向的吸收比率高达α_(c)/α_(a)≈3.2(λ=405 nm).此外,铁电自发极化在极轴(c轴)方向产生较高的内建电场,有利于产生优异光电性能.在光强为40 n W/cm^(2)的辐射光下,晶体探测器表现出显著的二向色性比(电流比Iphc/Ipha≈1.5)、较高的响应度(~39.5 m A/W)和探测率(~1.2×10^(12)Jones),以及较短的响应时间(~300μs)与出色的抗疲劳性能.

Polarized-light photodetectors are the indispensable elements for practical optical and optoelectronic device applications.Two-dimensional(2D)hybrid perovskite ferroelectrics,in which the coupling of spontaneous polarization(P_(s))and light favors the dissociation of photo-induced carriers,have taken a booming position within this portfolio.However,polarized-light photodetectors with a low detectionlimit remain unexplored in this 2D ferroelectric family.In this work,the high-quality individual crystals of a 2D perovskite ferroelectric,BA_(2)CsPb_(2)Br_(7)(1,where BA^(+)is n-butylammonium),were used to fabricate ultrasensitive polarized-light detectors.Its unique bilayered structural motif results in quite strong electric and optical anisotropy with a large absorption ratio of a_(c)/α_(a)≈3.2(λ=405 nm).Besides,the presence of ferroelectric Psalso endows high built-in electric field along the polar c-axis that favors photoelectric activities.Under an extremely low detectable limit of 40 n W/cm^(2),the detector of 1 exhibits a notable dichroism ratio(I_(ph)^(c)/I_(ph)^(a)≈1.5),a large responsivity of~39.5 m A/W and a specific detectivity of~1.2×10^(12)Jones.Moreover,crystal-based devices of 1 also exhibit a fast response speed(~300μs)and excellent anti-fatigue merits.This work highlights great potentials of hybrid perovskite ferroelectrics toward polarized-light photodetection.