Conjugated Polymer Blends for High Contrast Black‐to‐Transmissive Electrochromism

Abstract Next‐generation electrochromic technologies, such as dimmable fenestration, eyewear integrated displays, and optical shutters require materials that reversibly transition between highly transmissive and broadly absorbing achromatic states, often with minimal intermediate coloration. In this work, it is shown how the properties of dioxythiophene‐based electrochromic polymers (ECPs) can be leveraged through straightforward color mixing to yield high‐contrast, black‐to‐transmissive materials with low driving voltages (<1 V), extended functional lifetimes, and minimal transient chromaticity. Drawing from a family of five soluble colored‐to‐colorless switching polymers (including ECP‐cyan, ‐green, ‐magenta, ‐yellow, and a newly reported ECP‐orange), three unique cathodically coloring polymer blends are reported, with achromatic neutral states (C*_ab < 5) and integrated optical contrast exceeding 40% across the entire visible spectrum (380–780 nm). By incorporating different high‐gap and dual‐band absorbing ECPs, subtle control is demonstrated over both the extreme and intermediate coloration of the blends. This work showcases how solution coprocessing of ECPs can be used to access highly targeted achromatic hues while also enabling fine‐tuned neutral optical transition between black and transmissive states.