Translucent Photodetector with Blended Nanowires–Metal Oxide Transparent Selective Electrode Utilizing Photovoltaic and Pyro‐Phototronic Coupling Effect

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 15; no. 10; pp. e1804346 - n/a
• Main Authors: Abbas, Sohail, Kumar, Mohit, Kim, Dong‐Wook, Kim, Joondong
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.03.2019
• Subjects: Charge transport; Coated electrodes; Current carriers; Electrodes; Indium tin oxides; Nanotechnology; Nanowires; Optoelectronics; Photometers; Pyroelectricity; pyro‐phototronic; self‐biased; Silver; silver nanowires; transparent; ultra‐violet (UV) photodetectors; Zinc oxide; silver nanowires; self-biased; ultra-violet (UV) photodetectors; transparent; pyro-phototronic
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.201804346

ZnO is a potential candidate for photodetection utilizing the pyroelectric effect. Here, a self‐biased and translucent photodetector with the configuration of Cu4O3/ZnO/FTO/Glass is designed and fabricated. In addition, the pyroelectric effect is effectively harvested using indium tin oxide (ITO), silver nanowires (AgNWs), and a blend of AgNWs‐coated ITO as the transparent selective contact electrode. The improved rise times are observed from 1400 µs (bare condition; without the selective electrode) to 69, 60, 7 µs, and fall times from 720 µs (bare condition) to 80, 70, 10 µs for corresponding ITO, AgNWs, and AgNWs‐coated ITO contact electrodes, respectively. Similarly, the responsivity and detectivity are enhanced by about 4.39 × 107 and 5.27 × 105%, respectively. An energy band diagram is proposed to explain the underlying working mechanism based on the workfunction of the ITO (4.7 eV) and AgNWs (4.57 eV) as measured by Kelvin probe force microscopy, which confirms the formation of type‐II band alignment resulting in the efficient transport of photogenerated charge carriers. The functional use of the transparent selective contact electrode can effectively harness the pyro‐phototronic effect for next‐generation transparent and flexible optoelectronic applications. The effective utilization of photovoltaic and pyro‐phototronic effect facilitates an ultrahigh‐performing self‐biased translucent photodetector by introducing transparent AgNWs, ITO, and their blended structure on Cu4O3/ZnO heterojunction. The underlying working mechanism is explored by various material and electrical characterization tools. Specifically, Kelvin probe force microscopy measurement verifies formation of feasible type‐II band alignment due to suitable workfunction of selective electrodes with heterojunction.