All-Printed ZnO Nanowire-Based High Performance Flexible Ultraviolet Photodetectors

Sensor-laden flexible electronic systems offer opportunities to develop a wide range of applications including healthcare, electronic skin (e-skin) in robotics, Internet of Things (IoT), etc. However, the mass production of sensors, needed for these applications, could be a huge challenge when developed with inherently wasteful conventional fabrication processes. In this regard, a resource-efficient manufacturing method using eco-friendly (green) materials is desirable. Herein, we present a resource-efficient additive manufacturing route for printing a
$4\times $
4 ultraviolet (UV) photodetectors (PSs) array on flexible substrates. Specifically, we use the contact printing technique to realize high-grade UV-sensitive and uniform electronic layers of zinc oxide (ZnO) nanowires (NWs). Next, high-resolution extrusion-based direct ink write (DIW) printing is employed to define metal electrodes and the sensing channel area. The fabricated devices exhibit excellent UV sensing performance at low bias voltage (1 V) and light intensity (
$0.5~\mu \text{W}$
/cm
$^{2}$
), including an average responsivity of
$\sim 7.8\times 10^{6}$
A/W, specific detectivity
$\sim 1.7\times 10^{16}$
Jones, external quantum efficiency (EQE)
$\sim 2.6\times 10^{9}$
%, and current ON/OFF ratio
$\sim 2\times 10^{3}$
. The mechanical loading (bending) tests performed under different radii of curvature (10–40 mm) confirm the robust performance of devices. This work shows a potential way toward the next generation of sustainable electronics manufacturing.