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

Organic-inorganic (hybrid) metal halide perovskites(MHPs)incorporating chiral organic ligand molecules are naturally sensitiveto left- and right-handed circular polarized light, potentially enablingselective circular polarized photodetection. Here, the photoresponsesin chiral MHP polycrystalline thin films made of ((S)-(-)-alpha-methylbenzylamine)(2)PbI4 and ((R)-(+)-alpha-methylbenzylamine)(2)PbI4, denoted as (S-MBA)(2) PbI4 and (R-MBA)(2)PbI4, respectively,are investigated by employing a thin-film field-effect transistor(FET) configuration. The left-hand-sensitive films made of (S-MBA)(2)PbI4 perovskite show higher photocurrent underleft-handed circularly polarized (LCP) light than under right-handedcircularly polarized (RCP) illumination under otherwise identicalconditions. Conversely, the right-hand-sensitive films made of (R-MBA)(2)PbI4 are more sensitive to RCP than LCP illuminationover a wide temperature range of 77-300 K. Furthermore, basedon FET measurements, we found evidence of two different carrier transportmechanisms with two distinct activation energies in the 77-260and 280-300 K temperature ranges, respectively. In the formertemperature 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 magnitudelarger activation energy dominate. Both types of chiral MHPs showintrinsic p-type carrier transport behavior regardless of the handedness(S or R) of these materials. The optimal carrier mobility for bothhandedness of material is around (2.7 +/- 0.2) x 10(-7) cm(2) V-1 s(-1) at 270-280K, which is two magnitudes larger than those reported in nonchiralperovskite MAPbI(3) polycrystalline thin films. These findingssuggest that chiral MHPs can be an excellent candidate for selectivecircular polarized photodetection applications, without additionalpolarizing optical components, enabling simplified construction ofdetection systems.