Push-Pull Biphenyl Liquid Crystals Enabling Low-Voltage-Driven Light-Emitting Devices

Light-emitting liquid-crystal displays (LE-LCDs) are considered energy-efficient display technologies because they eliminate energy losses caused by polarizers and color filters. Although we previously developed an LE-LCD prototype based on π-extended stilbene derivatives, its practical application was hindered by a high driving voltage. In this study, we improved the device performance by employing a newly developed liquid crystal mixture of push-pull biphenyl derivatives (NB-5). NB-5 maintains a nematic phase at room temperature and exhibits intrinsic luminescent properties, enabling the realization of an electro-optical fluorescence switching device operable at 30°C. The resulting device shows a remarkably low threshold voltage and operates at only a few volts. In addition, NB-5 exhibits excellent birefringence and high dichroic ratios. These results demonstrate the effectiveness of push-pull molecular design in improving electro-optical responsiveness and highlight the potential of NB-5 for the practical implementation of low-voltage-driven LE-LCDs.