Unique Perovskitizer N─Pb Bond Switching Induced Polar Photovoltaic Effect in Trilayered Hybrid Perovskite

Abstract

AbstractPolar photovoltaic effect (PPE) has attracted great attention in regulating desired optoelectronic properties, which can be driven by order–disorder and displacive phase transitions. Bond‐switching is also a feasible method to induce PPE, but such investigation is very rare. Lead‐halide hybrid perovskite (LHHP) is an outstanding photodetection material; lead atoms possess rich coordination modes to provide possibilities to construct switchable bonds. Here, a unique perovskitizer N─Pb bond‐switching is disclosed to induce polar photovoltage in the emerging LHHP, PA2MHy2Pb3Br10 (1, PA = n‐propylamine, MHy = methylhydrazine). Interestingly, the perovskitizer MHy+ provides 2s2 lone pair while the Pb atom affords empty d orbitals, which coordinate with each other to generate a flexible N─Pb bond. Further, the introduction of N─Pb bonds results in a high distortion of the PbBr6 octahedron to form local polarity and further orientation to induce spontaneous polarization. More importantly, such a flexible N─Pb bond switching mechanism drives a notable PPE and controllable polarized photo‐response, a polarization ratio up to 9.7 at the polar phase in striking contrast with the non‐polar phase (1.03). The work provides the first demonstration of bond‐switching to induce polar phase transition and polar photovoltage in the photoconductive hybrid perovskites for photoelectric applications.