Out-of-plane photoconductive and bulk photovoltaic effects in two-dimensional α-In2Se3/Ta2NiS5 ferroelectric heterojunctions

Abstract

Two-dimensional [Formula: see text]-In2Se3 exhibits simultaneous intercorrelated in-plane and out-of-plane polarization, making it a highly promising material for use in memories, synapses, sensors, detectors, and optoelectronic devices. With its narrow bandgap, [Formula: see text]-In2Se3 is particularly attractive for applications in photodetection. However, relatively little research has been conducted on the out-of-plane photoconductive and bulk photovoltaic effects in [Formula: see text]-In2Se3. This limits the potential of [Formula: see text]-In2Se3 in the device innovation and performance modification. Herein, we have developed an [Formula: see text]-In2Se3-based heterojunction with a transparent electrode of two-dimensional Ta2NiS5. The out-of-plane electric field can effectively separate the photo-generated electron–hole pairs in the heterojunction, resulting in an out-of-plane responsivity (R), external quantum efficiency (EQE), and specific detectivity ([Formula: see text]) of 0.78[Formula: see text]mA/W, 10[Formula: see text]% and [Formula: see text] Jones, respectively. The out-of-plane bulk photovoltaic effect has been demonstrated by changes in the short circuit current (SCC) and open circuit voltage ([Formula: see text]) with different optical power intensity and temperature, which indicates that [Formula: see text]-In2Se3-based heterojunctions has application potential in mid-far infrared light detection based on its out-of-plane photoconductive and bulk photovoltaic effects. Although the out-of-plane photoconductive and bulk photovoltaic effects are relatively lower than that of traditional materials, the findings pave the way for a better understanding of the out-of-plane characteristics of two-dimensional [Formula: see text]-In2Se3 and related heterojunctions. Furthermore, the results highlight the application potential of [Formula: see text]-In2Se3 in low-power device innovation and performance modification.