Bulk photovoltaic effect enhancement via electrostatic control in layered ferroelectrics

TL;DR

This paper demonstrates how electrostatic control in layered ferroelectrics can significantly enhance the bulk photovoltaic effect by manipulating shift current responses through structural and electronic engineering.

Contribution

It introduces a method to enhance BPVE in layered ferroelectrics by electrostatic control, linking orbital character to shift current behavior from first principles.

Findings

Shift current can be predicted by covalent orbital character.

Electrostatic control enhances shift current in layered structures.

Layered heterostructures are ideal for BPVE applications.

Abstract

The correlation between the shift current mechanism for the bulk photovoltaic effect (BPVE) and the structural and electronic properties of ferroelectric perovskite oxides is not well understood. Here, we study and engineer the shift current photovoltaic effect using a visible-light-absorbing ferroelectric Pb(Ni$_{x}$Ti$_{1-x}$)O$_{3-x}$ solid solution from first principles. We show that the covalent orbital character dicates the direction, magnitude, and onset energy of shift current in a predictable fashion. In particular, we find that the shift current response can be enhanced via electrostatic control in layered ferroelectrics, as bound charges face a stronger impetus to screen the electric field in a thicker material, delocalizing electron densities. This heterogeneous layered structure with alternative photocurrent generating and insulating layers is ideal for BPVE applications.