Synergetic effects of ligand exchange and reduction process enhancing both electrical and optical properties of Ag nanocrystals for multifunctional transparent electrodes

• Published in: Nanoscale 2018-10, Vol.10 (38), p.18415-18422
• Main Authors: Kang, Min Su, Joh, Hyungmok, Kim, Haneun, Yun, Hye-Won, Kim, Donggyu, Woo, Ho Kun, Lee, Woo Seok, Hong, Sung-Hoon, Oh, Soong Ju
• Format: Article
• Language: English
• Subjects: Combinatorial analysis; Design optimization; Electrical resistivity; Electrodes; Figure of merit; Heat exchange; Ligands; Low conductivity; Metal compounds; Nanocrystals; Optical properties; Optoelectronics; Organic chemistry; Reduction; Sensors; Silver; Thin films
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c8nr05212c

In this work, we introduce a low cost, room-temperature and atmospheric pressure based chemical method to produce highly transparent, conductive, and flexible nano-mesh structured electrodes using Ag nanocrystals (NCs). Sequential treatments of ligand exchange and reduction processes were developed to engineer the optoelectronic properties of Ag NC thin films. Combinatorial analysis indicates that the origin of the relatively low conductivity comes from the non-metallic compounds that are introduced during ligand exchange. The reduction process successfully removed these non-metallic compounds, yielding structurally uniform, optically more transparent, dispersive, and electrically more conductive thin films. We optimized the design of Ag NC thin film mesh structures, and achieved low sheet resistance (9.12 Ω □-1), high optical transmittance (94.7%), and the highest figure of merit (FOM) of 6.37 × 10-2. Solution processed flexible transparent heaters, touch pads, and wearable sensors are demonstrated, emphasizing the potential applications of Ag NC transparent electrodes in multifunctional sensors and devices.