Nano-to-Microporous Networks via Inkjet Printing of ZnO Nanoparticles/Graphene Hybrid for Ultraviolet Photodetectors

Abstract

Inkjet-printed photodetectors have gained enormous attention over the last decade. However, device performance is limited without post-processing, such as annealing and UV exposure. In addition, it is difficult to manipulate the surface morphology of the printed film using an inkjet printer due to the limited options of low viscosity ink solutions. Here, we employ a concept involving the control of the inkjet-printed film morphology via modulation of co-solvent 2 vapor pressure and surface tension for the creation of a high-performance ZnO-based photodetector on a flexible substrate. The solvent boiling point across different co-solvent systems is found to affect the film morphology, which results in not only distinct photo-response time but also photo-detectivity. ZnO-based photodetectors were printed using different solvents which display a fast photo-response in low-boiling point solvents due to the low carbon residue and larger photo-detectivity in high-boiling point solvent systems due to the porous structure. The porous structure is obtained using both gas-liquid surface tension differences and solid-liquid surface differences, and the size of porosity is modulated from nano-size to micro-size depending on the ratio between two solvents or two nanomaterials. Moreover, the conductive nature of graphene enhances the transport behavior of the photocarrier, which enables a high-performance photodetector with high photo-responsivity (7.5*10 2 AW-1) and fast photo-response (0.18 s) to be achieved without the use of high-boiling point solvents. section image of printed thin films (Figure S6); the detail information of device preparation and characterisation methods; SEM (Figure S7) and AFM images (Figure S8) of as-printed thin films;

Applications of Ceramic/Graphene Composites and Hybrids

“…Within the same ZnO np /graphene system, researchers have fabricated a porous photodetector film by inkjet printing taking advantage of the different volatility of co-solvents and the change in surface tension by the graphene presence to create controlled microporosity in the films. The I light /I dark ratio of the composite films although small it proved larger than that of the pure ZnO film, and increased with porosity as well [ 345 ].…”

Design of Chemically Stable Organic Perovskite Quantum Dots for Micropatterned Light‐Emitting Diodes through Kinetic Control of a Cross‐Linkable Ligand System

“…The rheological parameters (viscosity η, surface tension γ, and density ρ) of the perovskite QD/Stable LS ink give a Z value of ≈18.9 (where Z is the inverse of the Ohnesorge number, ( Oh −1 ) = ( γρa ) 1/2 /η; η QD ≈2.1 mPa s, γ QD ≈19.2 mN m −1 , ρ QD ≈3.83 g cm −3 , nozzle diameter a = 21.5 μm), which is within the optimal range for inkjet printing (2 < Z < 24). [ 31 ] The pristine QDs in benzene promote coffee ring effects, as shown in Figure 4b, [ 32 ] whereas the formulated ink with the cosolvents forms a homogeneous microsized pattern, as shown in Figure 4c. The height of the perovskite QD film after three printing cycles is approximately 75 nm, and the edge‐to‐center height ratio is only 1.25, corresponding to a small coffee ring effect (Figure 4c); the ratio remains low after one printing cycle (≈1.31, Figure 4d).…”

Fabrication, material regulation, and healthcare applications of flexible photodetectors

“…In addition, inkjet printing can also achieve large-area, high-resolution maskless manufacturing. 34 For instance, Lien et al embedded ZnO and Ag nanowires into thermoplastic polyurethane through inkjet printing to prepare a completely transparent flexible PD, as shown in Fig. 1f.…”