Black-To-Transmissive Electrochromism

Electrochromic devices (ECDs) are widely recognized for their ability to modulate optical and thermal properties in response to an applied voltage. Their potential for energy conservation in buildings and sustainable technologies has been well established. More recently, the emergence of next-generation visual systems—such as augmented and mixed reality—has revealed new opportunities for electrochromics, accompanied by increased performance demands. These applications require devices with enhanced transparency, faster switching speeds, and long-term reliability. To meet these needs, it is essential to understand the material properties, interfacial interactions, and underlying electrochemical mechanisms that govern device behavior. This dissertation addresses these challenges through a combined approach of material design and device engineering aimed at improving the overall performance of black electrochromic systems.

We first established a standardized framework for constructing complementary ECDs to reduce energy consumption while enhancing color modulation. A p-type electrochromic polymer was paired with an n-type polyazoisoindigo (PAI), enabling synergistic switching and broad-spectrum absorption. Optical modeling was employed to guide electrode pairing and achieve subtractive color mixing, yielding high-contrast black-to-transmissive transitions with elevated coloration efficiency. To further refine the electrochromic color space, we tuned the optical properties of magenta ProDOT-based polymers by introducing structural substituents that modulate planarity and absorption without compromising redox stability. Despite these advances, conventional conjugated electrochromic polymers remain limited by residual absorption in their bleached state. To overcome this, a new class of meta-conjugated electrochromic polymers was developed, exhibiting transparent-to-black switching with minimal background absorption. These materials are highly transparent in the neutral state and strongly absorbent when doped, delivering exceptional optical contrast and enabling next-generation black ECDs. Collectively, these studies demonstrate the effectiveness of rational polymer design and device architecture in advancing electrochromic technologies for modern applications.