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

Abstract

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 4×4 ultraviolet (UV) photodetectors array on flexible substrates. Specifically, we use contact printing technique to realise high-grade UV sensitive and uniform electronic layers of 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 (1V) and light intensity (0.5μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), including an average responsivity of ~7.8×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> A/W, specific detectivity ~1.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</sup> Jones, external quantum efficiency ~2.6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> % and current on/off ratio ~2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The mechanical loading (bending) tests performed under different radii of curvature (10 to 40mm) confirm the robust performance of devices. This work shows a potential way towards next generation of sustainable electronics manufacturing.