Phase Change Materials for Nonvolatile, Solid‐State Reflective Displays: From New Structural Design Rules to Enhanced Color‐Changing Performance

Abstract

Abstract With the arrival of omnimedia era, there has been an increasing demand for energy‐saving, colorful, and portable displays. Traditional display technologies, such as electrophoresis and electronic ink display suffer from low color switching speed and poor color richness. Due to their high performances, phase change materials (PCMs)‐based nonvolatile, solid‐state reflective display coatings have become the most promising materials for new portable display technology. Existing researches mainly focus on improving the color‐changing performance of coatings by optimizing film structural parameters, but ignore improving the performance by designing new PCMs. Here, this study reveals the color‐changing mechanisms of display coatings through a combination of experiments, first‐principles calculations, spectral fitting, and optical simulation. It is found that reducing the vacancy concentrations of PCMs can increase the color‐changing performance of coatings owing to the increase in p–p coupling strength. Based on previous reports and the new insights into p–p coupling strength, this study proposes three structural design principles of ideal PCMs (low ionicity, a limited degree of hybridization, and high p–p coupling strength) and predicts new PCM candidates for display applications. This study opens a broad avenue for developing nonvolatile display technologies and material selection.