Boosting Self‐Powered Ultraviolet Photoresponse of TiO₂‐Based Heterostructure by Flexo‐Phototronic Effects

Abstract

Ultraviolet photodetectors have long been used as key elements for various applications, including optical sensing and communication. However, accurate sensing of weak UV intensities under self‐powered conditions with stable photocurrent and rapid temporal response remains critical because of challenges related to having suitable band alignment and strong junction quality. Here, an enhancement in the self‐power ultraviolet (UV, λ = 365 nm) photoresponse of the silver nanowires/TiO2 Schottky photodetector is demonstrated by taking advantage of the flexoelectric phenomenon. The device does not show measurable photocurrent under self‐biased conditions with low‐intensity (200 µW cm–2) UV illumination, whereas a significant photocurrent of about 0.48 µA is measured by integrating the photovoltaic and flexo‐phototronic effects. Additionally, rise/fall times improved from 300/1068 to 43/165 µs by utilizing the flexo‐phototronic effects, depicting an enhancement of 597%. Further, remarkable responsivity of 124 mA W–1 and high detectivity of 6.5 × 1011 Jones under self‐biased conditions are recorded. Moreover, microscopic evidence of flexoelectric effect modulated photoresponse is provided by photoconductive atomic force microscopy measurements. High efficiency and self‐powered capability demonstrated in this study are likely to inspire the development of next‐generation ultrafast, energy‐efficient, and sophisticated photodetectors for communication, imaging, and sensing networks.

Flexoelectricity‐Enhanced Self‐Powered Photodetection in 2D van der Waals Heterojunctions With Large Curvatures

“…[19][20][21] The flexoelectric effect has been used to modulate various properties of bulk materials, such as electron transport and optical performance. [22][23][24][25][26][27] 2D vdW materials have extremely small thicknesses and excellent flexibilities, making them capable of withstanding larger deformations compared to their bulk counterparts. [28][29][30][31][32] By means of a large, non-uniform deformation-induced flexoelectric field, it is possible to dramatically modulate the optoelectronic properties of 2D materials.…”

Realization of Self‐Powered High‐Performance Photodetection via Electrostatic Field Enhancement and Dark Current Suppression

“…[10][11][12][13][14][15] Typically, these semiconductor materials were constructed to be p-n junctions, heterojunctions, or Schottky junctions, and photogenerated carriers are separated through the built-in electric field of the junctions. [16][17][18][19][20] A robust built-in electric field is crucial for achieving high-performance UV detection. Great efforts are made to boost the built-in electric field including interface modification, energy-level regulation, and other effect coupling.…”