RESUMO
Alternating current electroluminescence (ACEL) has great potential in flexible displays, especially in textile displays. However, since ACEL needs high-frequency, high-voltage AC signal to drive, there remains no driving scheme for pixelated ACEL display to achieve multiple gray scales. In this work, a driving scheme based on full-bridge inverters is proposed for passive-matrix ACEL (PMACEL) display, which achieves multiple gray scales by changing the duty cycle of the square wave. A single-pixel ACEL displaying 16 gray levels (4 bits) and a 5 × 8 fabric PMACEL displaying eight gray levels are demonstrated, enabling flexible ACEL devices to exhibit more vivid tones on a fabric substrate.
RESUMO
Electrophoretic displays (EPDs) utilize the electrophoretic particles in electronic ink (e-ink) to display different color states with bistability. Bistability of EPDs is achieved by placing colloidal particles in a highly viscous solvent to keep the distribution of colloidal particles stable without sustaining the external field, so it only consumes power when updating the image. The feature of low power consumption makes it suitable for applications such as advertising boards, price tags, etc. Apart from these applications, recent research on lateral-driving EPDs extends its applications to smart windows, privacy control, and so on. However, achieving bistability by simply increasing the viscosity of solvent is inefficient in the case of lateral driving operation. Therefore, it is deserving to have intensive study on the mechanism of bistability from other aspects. Herein, we propose a mechanism to investigate the charge adsorption behavior on the electrode to affect the bistability of particles, which is based on the "Stern layer adsorption/desorption" model. Based on the above mechanism, we further fabricated a hexadecyl trimethylammonium bromide (CTAB)/poly(vinyl alcohol) (PVA) composite film on the electrode to improve the bistability of lateral-driving EPD by reducing the diffusion current caused by unabsorbed charges. This developed lateral-driving EPD can significantly improve the bistability, which is enhanced from 40 s to 7 min, an increase by a factor of approximately 10. This work gives a way to consider the bistability of colloidal particles in nonpolar solvent.
RESUMO
In-plane switching electrophoretic display (IPS-EPD) is an emerging field of display technology which achieves particles moving horizontally through a lateral electric field. Compared to vertically driven electrophoretic display (V-EPD), IPS-EPD exhibits the feasibility of transparent display function. However, most of the previous research was hindered by long response time, low optical transmittance, or complex structures. In this paper, we have proposed a newly developed electrode layout and driving waveform for IPS-EPD, achieving a device with fast response time of 0.32 s, high transmittance of 58.07%, good transmittance-contrast ratio of 11.25, and simple structure, which show a significant improvement over other related research. Additionally, we elucidated the physical mechanism for the device through developing a particles motion simulation. Finally, we presented a prototype of an IPS-EPD with TFT panel, which exhibits excellent performance in various application scenarios, making it a possible application prospect in mobile phone cases, glasses, windows, and so on.
RESUMO
As a pivotal component in human-machine interactions, display devices have undergone rapid development in modern life. Displays such as alternative current electroluminescence|alternative current electroluminescent (ACEL) devices with high flexibility and long operational lifetimes are essential for wearable electronics. However, ACEL devices are constrained by their inherent high driving voltage and complex fabrication processes. Our work presents an easy blade-coating method for fabricating flexible ACEL display devices based on an all-solution process. By dispersing BaTiO3 and ZnS/Cu powder into waterborne polyurethane, we successfully combined dielectric and fluorescence functionalities within a single layer, significantly reducing the device's driving voltage. Additionally, the ionic conducting hydrogel was chosen as a transparent electrode to achieve good electrical contact and strong interfacial adhesion through in situ polymerization. Owing to the unique method, our ACEL device exhibits high flexibility, low driving voltage (20-100 V), high brightness (300+ cd/m2 at 60 V), and environmental friendliness. Furthermore, by repurposing the hydrogel electrode, we integrated strain visualization capabilities within a single device, highlighting its potential for applications such as wearable healthcare monitoring.