All 3D-Printed Flexible ZnO UV Photodetector on an Ultraflat Substrate

Abstract

An all three-dimensional (3D)-printed flexible ZnO ultraviolet (UV) photodetector is demonstrated, where the 3D-printing method is used not only for the electrode and photosensitive material but also for creating a substrate. An ultraflat and flexible substrate capable of serving as the backbone layer is developed using a water-dissolvable polymer layer for surface planarization. A two-layered printing followed by surface treatment is demonstrated for the substrate preparation. As mechanical support but flexible, a thick and sparse thermoplastic polyurethane layer is printed. On its surface, a thin and dense poly­(vinyl alcohol) (PVA) is then printed. A precise control of PVA reflow using a microwater droplet results in a flexible and extremely uniform substrate. A Cu–Ag nanowire network is directly 3D printed on the flexible substrate for the conducting layer, followed by ZnO for the photosensitive material. Unlike the planar two-dimensional printing that provides thin films, 3D printing allows the electrode to have a step height, which can be made like a dam to accommodate a thick film of ZnO. Photosensitivity as a function of various ZnO thickness values was investigated to establish an optimal thickness for UV response. The device was also tested in natural sunlight along with stability and reliability.

Highly Sensitive UV Photodiode Composed of β-Polyfluorene/YZnO Nanorod Organic-Inorganic Hybrid Heterostructure

“…where J dark is the current density at dark space. Due to the low value of J dark (=1.06 × 10 −6 A/cm 2 ) and the large magnitude of η QE for our Y3 device, D * was computed to be 3.34 × 10 12 cm•Hz 1/2 •W −1 by using Equations (2) and (3). This value is greater than others [50,51], except for that of the PFO/ZnO PD consisting of the avalanche type of multiple PFO/ZnO stacks [52] (See Table 1).…”

“…For the last two decades, ZnO nanostructures have garnered substantial attention because of their prodigious potential for blue and ultra-violet (UV) optoelectronic devices [1][2][3][4][5][6]. Among various nanostructures, 1-dimensional ZnO (e.g., nanorod [7,8], nanoneedle [9,10], nanopillar [11,12], etc.)…”

“…To our best awareness, however, ZnO/PFO-based light-sensing photodiodes (PDs) have rarely been investigated [ 50 , 51 , 52 ] in spite of great potential for highly sensitive UV detection (e.g., space exploration, environmental monitoring, flame detection, defense warning, medical equipment, security communication systems, etc. [ 1 , 2 , 3 , 4 ]).…”

UV-Responsive Screen-Printed Porous ZnO Nanostructures on Office Paper for Sustainable and Foldable Electronics

“…Besides, contrary to our work, a high loading content of small-sized (<100 nm) commercial ZnO nanoparticles (40 wt%) were needed to form a continuous and functional composite matrix on the irregular and punctually defective cork surface. Beyond the listed works displayed in Table 1, the screen-printed CMC/ZnO sensors on office paper also exhibit a comparable or even superior performance than some of recently published ZnO-based UV sensors comprising expensive materials and/or complex, time-consuming and energy-intensive processing methods [75,76,[81][82][83][84][85]. Figure 4a,b depict the average photocurrent of the UV sensors under different applied voltages (0.25, 0.5, 1, and 2 V) and the corresponding response current (∆I) and responsivity.…”

Atmospheric Pressure Plasma Printing of Nanomaterials for IoT Applications

“…Printed and flexile electronics has been receiving much attention recently and emerging as an important research area to meet the anticipated demands of the Internet of Things (IoT). [1][2][3], memory [4][5][6][7], battery [8], supercapacitor [9,10], photovoltaics [11], energy scavengers [12,13], gas sensors [14][15][16], biosensors and lab-on-paper [17][18][19], heat therapy pad [20], UV sensors [21], pressure and other physical sensors [22,23], antennas [24,25], displays [26] and many others [27].…”