Inkjet-Printed Patterned Quantum Dots Film for High-Efficiency Displays

Abstract

Due to the effect of solution kinetics and crystallization kinetics of quantum dot (QD) during inkjet printing, the inkjet printing technique is prone to form coffee-ring patterns and in-homogenous films. Pioneering efforts are usually limited to mixed solvent or additive inks, in this paper, we investigated polymer QD films with good uniformity obtained by inkjet printing, in order to control the uniformity of quantum dot films in pixels, the mechanism of action of wettability science on inkjet printing was considered through the action of nitrous oxide (N2O) on the surfaces of substrates and banks. In the absence of N2O treatment, the inkjet-printed QD droplets would pile up and adhere to the bank walls due to capillary forces before the pinning process. With the N2O surface treatment, the contact angle of the QD ink on the substrate was increased from 16° to 62°. The wettability of the QDs between the substrate and the bank was reduced, and the side build-up phenomenon was significantly reduced. By changing the thickness of the QD film from 4.5 μm to 15 μm, the color coordinates of the spectrum were changed from (0.2320, 0.1556) to (0.1480, 0.6933).