Engineering ferroelectric-nanonet-based heterostructures enables superior photovoltaic effect and asymmetric switchability

Abstract

Layered pervoskite ferroelectrics with a coexistence of robust spontaneous polarization and large intrinsic conductivity exhibit unique photoelectric behavior, and manipulation of photovoltaic response in such ferroelectric-based heterostructure has driven significant research activity. Herein, a Bi2WO6 layered oxide with a coexistence of ferroelectricity and 2D potential well which effectively confines carrier transport was chosen and its orientated nanonet film was formed epitaxially by pulsed laser deposition technique. An excellent platform to investigate the role of the ferroelectric-semiconductor heterostructure in tuning photovoltaic characteristics was constructed by embedding a p-type nanoscale Sb2Se3 within the n-type Bi2WO6 nanonet matrix. The desired Bi2WO6/Sb2Se3 heterostructure optimized the three key steps from light to electricity, and exhibited a large and stable photovoltaic effect, achieving three/two orders of magnitude enhancement of the short-circuit photocurrent density/open-circuit voltage under laser irradiation in its vertical structure device. What is more, an electric-field-controlled switchable asymmetric photoresponse was clearly observed in Bi2WO6/Sb2Se3 device, due to interfacial Schottky barrier formation and its width and height modulation by poling-modified ferroelectric self-polarization. In contrast to classical ferroelectric photovoltaics, the photocurrent direction of the target device after reversed poling remained unchanged, implying the significant role of the polarization-dependent interfacial effect, rather than bulk photovoltaic effect.