The puzzle of electrochromism

Abstract

Electrochromic materials exhibit a reversible color change that is triggered by an applied voltage. Controlled color change, low voltage operation and the memory effect are three unique material properties defining electrochromic materials. As a result of an electron transfer or redox reaction, the material is able to switch between its bleached (transparent) and colored state. As this color change is a chemical reaction, it only requires an applied voltage to trigger and complete the electron transfer, thus afterwards the applied potential can be removed and the material will stay in its current state; i.e. the memory effect. Electrochromic materials are processed into a sandwich structure of thin layers that enable it to change color when a voltage is applied to it; i.e. an electrochromic device (ECD). An ECD operates through two electrodes that are connected to both the positive and negative of the voltage-source, and the two electrochromic layers. These electrochromic layers are separated by an electrolyte, that allows ion transfer, enabling change of color. Optimizing this layer structure, results into the definition of four stacking sequences, based on their vertical or co-planar stacking sequence (i.e. vertical stacking of the EC layers or merging of both EC layers in the same layer with separated electrodes) combined with the substrate used; conductive and insulating. These four stacking sequences are characterized on their transparency, shape/pattern changing abilities, coloring, design of the images displayed and interaction between the two EC layers; i.e. technical characterization. As result of this material characterization, ‘the puzzle of electrochromism’ is designed. ‘The puzzle of electrochromism is an edge-matching puzzle, with as goal to puzzle four geometric shapes by matching the sides of the adjacent puzzle pieces. Solving this puzzle communicates the goal of the demonstrator (i.e. the technical and experiential characterizations) to the puzzler, while emphasizing the simplicity and possibilities of integrating electrochromic materials in design. The ultimate goal is to inspire the puzzle to make use of electrochromic materials in their product designs, through exiting creativity and curiosity. When a puzzle piece is connected to the framework, a closed loop circuit is created between the voltage source and the coin cell battery, thus the puzzle piece will change its color. When the polarity is reversed (i.e. the puzzle piece is turned 180 degrees within the horizontal plane), it immediately switches from its primary EC layer to its secondary EC layer or vice versa. All primary EC layers will form the first puzzle to be created and all secondary EC layers the secondary puzzle. Meaning, ‘the puzzle of electrochromism’ is not just one puzzle, but includes two different puzzles. Besides the controlled color change, the other unique material properties it demonstrates are: low voltage operation, memory effect, simplicity and transparency. All individual puzzle pieces represent a different stacking sequence, through which the shape/pattern change (i.e. single and double image display), coloring (i.e. immediate and color flow), design of the images displayed (i.e. isolated and linked) and interaction between the two EC layers (i.e. overlap, connection and separation) are demonstrated. In the end, ‘the puzzle of electrochromism’ is a demonstrator making electrochromism easy understood, explainable and approachable for designers to use within their product designs; i.e. the aim of this thesis. On top of this, it is not only a good demonstrator but also a good puzzle according to the ten puzzle principles of Shell (2008).