Nanocomposites and nanomaterials

Quantum Rods Enhancement Film: From Design to Application
Prodanov M.F. 1, Zhang W. 2, Vashchenko V.V.1, Gupta S.2, Kwok H.-S.2, Srivastava A.K.2
1 Department of Technology of Organic Materials,
State Scientific Institution "Institute for Single Crystals" of NASU
60, Nauky Ave., Kharkiv, 61001, Ukraine. 
E-mail: maksym.f.prodanov@gmail.com
2 State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, 
Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.

Planar aligned quantum rods (QRs) in polymer films can be used as enhancement films (EF) for LCDs backlight applications. In addition to the wider color gamut, polarized emission from the aligned QRs also improve the overall optical efficiency of LCDs. Recently, it was shown that photoaligned CdSe/CdS QRs in liquid crystalline polymer (LCP) with subsequent polymerization opens a way to fabricate a QREFs with highly polarized emission. [1] 
In this work the photoaligned quantum rods in liquid crystal polymer were explored for application in displays backlighting depending on the composition of the ligands shell on the nanoparticles surface. First, we proposed an approach to change the ligand shell of quantum rods without significant affecting the optical properties, and later studied their compatibility with liquid crystal polymer host. Promesogenic dendritic ligands in combination with relatively short alkylphosphonic acids were found to provide good optical quality, without nanoparticles aggregation, and so the high brightness, even at relatively higher concentrations of quantum rods in the host, which perfectly suits for the liquid crystal displays application. Afterward, a photo-aligned QREF with thickness ~ 350 nm have been fabricated by ink-jet printing that gives the brightness of 248 nits and high polarization ratio. The proposed approach was used for the fabrication of 2.5 inch display prototype with QREF as backlight and it is highly viable for the application in modern flat-panel LCDs.

1.	Srivastava A.K., Zhang W., Schneider J., Rogach A.L., Kwok H.-S. Photoaligned Nanorod Enhancement Films with Polarized Emission for Liquid-Crystal-Display Applications // Adv Mat.-2017.-29,-P. 1701091.