Solution-processed Flexible Transparent Electrodes and Reflective Electrodes

Principal Investigator: Professor Wallace C.H. CHOY (Professor from Department of Electrical and Electronic Engineering)

This project is showcased in the third exhibition – Technology for Future.

About the scholar

Professor Wallace C.H. CHOY

Research interests:
The design, physics, and mechanism of organic/inorganic optoelectronic devices; plasmonic nanostructures, nanoscale structures, and the hybrid systems with organic/inorganic materials; the multi-physical (optical, electrical, and thermal) properties and applications of the hybrid systems.

Email: chchoy@eee.hku.hk
Website: https://www.eee.hku.hk/people/chchoy/

Project information
Professor Choy’s team invented silver nanowire (NW) based flexible transparent electrodes (FTEs) and silver nanoparticle (NP) electrodes. They both have attractive electrical and optical properties, and low-cost. By intergrating both inventions (that is disposing a layer of nanoparticle on the NW FTEs), it can be used as flexible organic photovoltaics.
Flexible Organic Photovoltaics

(i) Flexible Transparent Electrodes (FTEs)

Silver nanowire (NW) based FTEs with attractive electrical and optical properties, low-cost, low-carbon production and good mechanical flexibility serving as a potential alternative to the conventional FTEs (e.g. ITO is brittle, high cost, and high carbon-footprint in production).

(i) Reflective Electrodes

Silver nanoparticle (NP) based electrodes with attractive electrical and optical properties, low-cost, high multiple stabilities serving as a potential candidate to the reflective top electrodes for optoelectronic applications (e.g. organic solar cells and light emitting diodes)

Project video
Project images
FTE: (a) Optical diffused transmission and electrical sheet resistance of ITO/glass and solution-processed FTEs. (b) Atomic force microscopic image of solution-processed FTEs and the corresponding height profile for the measuring line. The measured RMS and peak-valley roughness are <1 and <3 nm, respectively. (c) Sessile drop of water on solution-processed FTEs in air. The measured contact angle is 18.4°
(a) Synthesis process of silver nanoparticles; the inset image is the SEM image of AgNPs. (b) Spray coating of AgNPs. The inset photographs are the top and bottom views of an actual OPV device with a spray-coated AgNP electrode.
The reflectance spectrum and the conductivities-temperature curves of AgNPs thin films.
(a) The cross-section SEM image of the OPV with the structure of glass/ ITO/ PEDOT:PSS/ D18-Cl:N3:PC61BM/ PEI-Zn/ AgNP electrode. (b) The J-V characteristics of OPV. The inset image is the top view of a large-area device with an area of 1 cm².
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