CIS–ZnS quantum dots for self-aligned liquid crystal molecules with superior electro-optic properties

Abstract

We demonstrate self-aligned and high-performance liquid crystal (LC) systems doped with 1-dimensional (1D) chain-like clusters of CuInS₂ (CIS)–ZnS core–shell quantum dots (QDs). By changing the cell fabrication method of the LC–QD composites, we can selectively control the orientation of the LC molecules between the homogeneous and homeotropic states without conventional LC alignment layers. The homeotropic alignment of LCs was achieved by random dropcasting and the homogeneous alignment was performed using a capillary injection of LC–QDs due to the random or linear diffusion of QD clusters into ITO defects. The electrically compensated bend (ECB)- and vertically aligned (VA) mode LC displays (LCDs) containing our LC–QD composite both showed superior electro-optic (EO) properties. A 37.1% reduction in the threshold voltage (V_th) and a 36.6% decrease in the response time were observed for ECB mode LCDs, and a 47.0% reduction in the V_th and a 38.3% decrease in the response time were observed for VA mode LCDs, meaning that the proposed LC–QD composites have a great potential for the production of advanced flexible LCDs.