Two-Dimensional Guanidine-Based Hybrid Perovskites with Strong Dichroism for Multiwavelength Polarization-Sensitive...

Two-dimensional (2D) organic-inorganic hybrid perovskites, benefiting from their natural anisotropy of quantum-well motifs and optical properties, have shown remarkable polarization-dependent responses superior to the 3D counterparts. Here, for the first time, multiwavelength polarization-sensitive detectors were fabricated by using single crystals of a guanidine-based 2D hybrid perovskite, (BA)₂ (GA)Pb₂ I₇ (where BA⁺ is n-butylammonium and GA⁺ is guanidium). Its unique 2D quantum-well structure results in strong crystallographic-dependence of optical absorption. Strikingly, our crystal-based photodetector exhibits a prominent photocurrent dichroic ratio (I_max /I_min ) of ∼2.2 at 520 nm, higher than the typical 2D inorganic materials (GeSe, ∼1.09, PdSe₂ , ∼1.8). In addition, notable dichroic ratios of 1.29 and 1.23 at 405 nm and 637 nm are also created for the multiwavelength polarized-light detection. The prominent detecting performances, including low dark current (1.6×10^-11  A), considerable on/off ratio (∼2×10³ ), high photodetectivity (∼3.3×10¹¹ Jones) and responsivity (∼12.01 mA W^-1 ), make (BA)₂ (GA)Pb₂ I₇ a promising candidate for polarized-light detection. This work sheds light on the rational engineering of new 2D hybrid perovskites for the high-performance optoelectronic device applications.