Titania:Graphdiyne nanocomposites for high-performance deep ultraviolet photodetectors based on mixed-phase MgZnO

Abstract

Approachable graphdiyne (GDY), characterized by discrepancy hybridized carbon atoms of inhomogeneous π-bonding and carbon 2pz overlapping of orbitals, reveals versatility applications. Previously, interfaces high density between different structure materials induce the high response of photodetector, but the ratio of photocurrent to dark current is restricted for either limited materials properties or lattice mismatch when junctions formed. In this work, titania (TiO2) nanocrystals with a rational phase of anatase are encapsulated on GDY particles, further, the TiO2:GDY nanocomposites are synthesized. High specific surface area GDY, as a proper sustaining material optimizes the characters of TiO2 nanocrystals. Then TiO2:GDY nanocomposites cooperate with Mg0.3Zn0.7O (MZO) are mean to fabricate lateral bilayer ultraviolet photodetector. Because of the formed heterojunction between TiO2:GDY nanocomposites and MZO, the ultraviolet photodetector is highly sensitive to deep ultraviolet light, when optical band gap of MZO is as high as 3.8 eV. The responsivity of TiO2:GDY/MZO bilayer photodetector is also increased by more than one order of magnitude to 76 mA W−1 compares to the MZO device without TiO2:GDY nanocomposites while the photocurrent rejection is about three orders of magnitude from 254 nm to 365 nm. Meanwhile, signal-to-noise ratio is calculated as high as 1.5 × 105 in this work.