A continuous thermochromic energy storage material with three colors based on two color-changing mechanisms

In this work, a continuous thermochromic energy storage material (CTESM) was developed based on two distinct mechanisms, which provided a wider range of colors. Separate formulations of thermochromic energy storage materials were made using hexadecanol as the solvent, crystal violet lactone (CVL) as the color former, bisphenol A (BPA) as the developer, or crystal violet lactone and cresol red (CSR) interacting as color former and developer, respectively. More color changes were explored according to the above two combinations. Functional groups and thermal properties of CTESM were studied utilizing Fourier Transform Infrared, Thermogravimetry Analysis, X-ray diffraction and differential scanning calorimetry. This research indicates that the maximum color difference, which occurs in the condition that the ratio of CVL:BPA:CSR:HD is 2:1:2:140, enables transitions from blue-gray to green hues and then to red. Overall, CTESM has excellent thermal stabilities and cycling capabilities, leading to significant potential in anti-counterfeiting and sensors.