Ti₃C₂T_x MXene‐RAN van der Waals Heterostructure‐Based Flexible Transparent NIR Photodetector Array for 1024 Pixel Image Sensing Application

Abstract

The enriched surface functional group such as OH termination and unique 2D structure of Ti3C2Tx MXene provide the feasibility to form hydrogen bonds with organic photosensitive materials as van der Waals heterostructures, thus can realize the improved photoresponsivity of near infrared (NIR) photodetectors (PDs). In this work, an organic–inorganic van der Waals heterostructure‐based NIR PD array is designed using Ti3C2Tx MXene as conductive electrodes and RAN film as active materials (Ti3C2Tx‐RAN PDs). The on‐off ratio of the fabricated devices shows 6.25 times higher than that of PDs using thermal evaporated Au electrode (Au‐RAN PDs) under 1064 nm laser excitations. The fabricated Ti3C2Tx‐RAN NIR PDs also possess outstanding mechanical stability with no obvious photoresponse degradation under different bending states and high transparency with a transmittance above 70% in the visible region. Owing to the high performance of the Ti3C2Tx‐RAN PDs, a 1024‐pixel (32 × 32) image sensor array is fabricated to achieve delicate, vivid, and higher resolution imaging of a “deer,” opening up a new avenue for the biomimetic vision and flexible wearable accurate image sensing.

Air-Stable Flexible Photodetector Based on MXene–Cs3Bi2I9 Microplate Schottky Junctions for Weak-Light Detection

“…2D transition metal carbides and nitrides (MXenes) display great superiority as Schottky contact electrodes due to their ultrahigh conductivity, mechanical flexibility, chemical stability, tunable work function, and low-temperature processing methods. − Numerous experiments have shown that MXene–semiconductor van der Waals junctions formed at the contact surface are immune to chemical chaos and defects, which were able to obviate the Fermi level pinning effect and decrease the contrary tunneling currents. Up to now, MXene materials have been successfully integrated with Si, , TiO 2 , GaN, Te, and organic materials and demonstrated excellent optoelectronic properties.…”

“…32−34 Numerous experiments have shown that MXene−semiconductor van der Waals junctions formed at the contact surface are immune to chemical chaos and defects, which were able to obviate the Fermi level pinning effect and decrease the contrary tunneling currents. Up to now, MXene materials have been successfully integrated with Si, 35,36 TiO 2 , 37 GaN, 38 Te, 39 and organic materials 40 and demonstrated excellent optoelectronic properties.…”

MXene based flexible photodetectors: progress, challenges, and opportunities

“…The similar I dark along with the remarkable five orders of magnitude change in photocurrent demonstrate that MXene is as good as Ti/Au electrodes, providing an excellent choice for photoelectrical devices. Our group 52 also demonstrates a Ti 3 C 2 T x MXene–RAN van der Waals heterostructure-based flexible transparent near photodetector with a higher on–off ratio (6.25 times higher) compared with an Au–RAN photodetector.…”

“…4a shows the schematic illustration of the structures of a flexible photodetector with Mxene electrodes via the photolithography process. 52 In a typical procedure, the flexible PET substrate was placed in plasma cleaner for 30 min to enhance the hydrophilicity and wettability. Then, the photoresist was spread on the PET substrate.…”

“…Section 2 mainly covers the surface engineering of MXenes, including their intrinsic metallic conductivity and strategies toward semiconductive MXenes. 50,51 And then, fabrication procedures for MXene electronics are introduced, for example, photolithography, 52 laser direct writing, 53 spray coating, 54 filtration, 55 etc. In Section 4, we focus on promising optoelectronic devices based on MXenes.…”