Metal Halide Perovskite Photo-Field-Effect Transistors with Chiral Selectivity

Organic-inorganic (hybrid) metal halide perovskites (MHPs) incorporating chiral organic ligand molecules are naturally sensitive to left- and right-handed circular polarized light, potentially enabling selective circular polarized photodetection. Here, the photoresponses in chiral MHP polycrystalline thin films made of ((S)-(-)-α-methyl benzylamine)₂PbI₄ and ((R)-(+)-α-methyl benzylamine)₂PbI₄, denoted as (S-MBA)₂ PbI₄ and (R-MBA)₂PbI₄, respectively, are investigated by employing a thin-film field-effect transistor (FET) configuration. The left-hand-sensitive films made of (S-MBA)₂PbI₄ perovskite show higher photocurrent under left-handed circularly polarized (LCP) light than under right-handed circularly polarized (RCP) illumination under otherwise identical conditions. Conversely, the right-hand-sensitive films made of (R-MBA)₂PbI₄ are more sensitive to RCP than LCP illumination over a wide temperature range of 77-300 K. Furthermore, based on FET measurements, we found evidence of two different carrier transport mechanisms with two distinct activation energies in the 77-260 and 280-300 K temperature ranges, respectively. In the former temperature range, shallow traps are dominant in the perovskite film, which are filled by thermally activated carriers with increasing temperature; in the latter temperature range, deep traps with one order of magnitude larger activation energy dominate. Both types of chiral MHPs show intrinsic p-type carrier transport behavior regardless of the handedness (S or R) of these materials. The optimal carrier mobility for both handedness of material is around (2.7 ± 0.2) × 10^-7 cm² V^-1 s^-1 at 270-280 K, which is two magnitudes larger than those reported in nonchiral perovskite MAPbI₃ polycrystalline thin films. These findings suggest that chiral MHPs can be an excellent candidate for selective circular polarized photodetection applications, without additional polarizing optical components, enabling simplified construction of detection systems.