In situ constructed ferroelectric-nanonet-supported heterostructure thin film for high-performance photovoltaics

Heterostructure, which combines robust ferroelectrics and narrow-bandgap semiconductors together, is promising for acquiring both intensive photocurrent and large photovoltage output in photovoltaics; therefore, manipulation of the properties by engineering heterostructure has driven significant research activity. Herein, well-known Aurivillius-type ferroelectric Bi2WO6 and mullite-type Bi2Fe4O9 are chosen, and an excellent platform to investigate the role of ferroelectric-semiconductor heterostructure in tuning the photovoltaic effect is constructed by in situ depositing p-type nanoscale Bi2Fe4O9 onto n-type Bi2WO6 nanonet matrix. The nanonet-supported two-dimensional planar-like heterostructure and its ferroelectric domain switchability are confirmed by atomic force microscopy techniques. Significantly, the desired Bi2WO6/Bi2Fe4O9 film optimizes the key steps from light to electricity, and exhibits a large and stable photovoltaic effect, achieving four/three orders of magnitude enhancement of short-circuit photocurrent density/open-circuit voltage under laser irradiation. Furthermore, electric-field-controlled switchable asymmetric photoresponse and device stability were clearly observed, due to, in particular, Bi2WO6/Bi2Fe4O9 interfacial Schottky barrier formation and its modulation by poling-modified ferroelectric polarization. These findings highlight an important insight to construct diversified heterostructures with multi-functioning performances.