Conventional photodetectors (PDs) are based on measuring photocurrent, which is formed by the separation of electron-hole pairs generated in semiconductors upon light irradiation, through electrodes in direct contact with the semiconductors. Such devices are usually fabricated through complicated and precise processes such as thin film formation by vacuum deposition and fine patterning by photolithography and etching. In addition, PDs have a drawback that the contact quality between the electrode and the semiconductor is easily affected by external stress applied to the device. These issues make it difficult to implement a mechanically flexible device driven by conventional sensing mechanisms. Here we report a simple structured PD based on a semiconductor particle-polymer composite layer surrounded by two facing transparent electrodes, inspired by the fact that the dielectric properties of certain semiconductors change upon light irradiation with a photonic energy greater than or equal to their bandgap. In order to realize this, we synthesized a transparent and stretchable polymer, polyurethane-urea (PUU), which is compatible with Ag nanowires (AgNWs) and polydimethylsiloxane (PDMS) used for implementing stretchable electrodes, and dispersed ZnS:Cu particles into the PUU to form a sensory layer. The fabricated composite surrounded by two facing AgNW-based transparent electrodes was transparent and stretchable, and the capacitance formed at the composite sensitively changed upon irradiation of light with a wavelength of 420 nm and a power of 1.2 mW/cm2 even when the device was stretched or cut in half.
Bibliographical noteFunding Information:
This work was supported by a National Research Foundation of Korea (NRF) grant (Number 2015R1A4A1042417 , 2018R1D1A1B07047386 and Number 2016M3A7B4910 ) funded by the Korean government ( MSIP ). Further support was also provided by the Korea Institute of Industrial TechnologyProgram “Characteristics of VO2 Nanoink and Intense Pulsed Light Low-Temperature Sintering for Flexible Smart Window Films Using Direct Printing Technology ( KITECH EO-19-0006 )”. This work was also partly supported by the KIAT( Korea Institute for Advancement of Technology) grant funded by the Korea Government ( MOTIE: Ministry of Trade Industry and Energy ) (No. P0001018 , HRD program for Highly educated human resources development project on cutting-edge sensor technology for sensor industry acceleration). Partial support was also provided by the KSSRC program (Stretchable Multi Sensor for Wearable IoT Device) and the National Research Foundation of Korea(NRF) grant funded by the Korea Government(MSIT) (No. 2019R1A2B5B01070286 ).
© 2019 Elsevier Ltd
- Electrical properties
- Flexible composites
ASJC Scopus subject areas
- Ceramics and Composites
- General Engineering