Scientists in Finland have developed a new smart material that can both change color and store electrical energy.
In the future, this technology could lead to self-tinting windows that not only block excess sunlight but also store solar energy for later use.
The research was carried out by doctoral researcher Sachin Kochrekar at the University of Turku.
His work focused on creating thin films made from porphyrins, natural molecules found in living organisms.
Porphyrins play important roles in nature.
They are found in chlorophyll, which helps plants capture energy from sunlight, and in hemoglobin, the molecule that carries oxygen in human blood.
Because porphyrins are good at transferring electrons and changing their chemical state, scientists believe they could be useful for advanced materials and energy technologies.
In the study, researchers created new membrane-like materials using two different approaches. One method combined porphyrins with an electrically conductive material.
The other connected porphyrins together using special bridge molecules to form a polymer film.
The team also investigated how adding different metals affected the material’s performance. Some films contained nickel, some contained zinc, and others contained no metal at all.
Even these small changes had a major impact on how the materials behaved.
The nickel-based material was able to switch between three different colors, while the zinc-based and metal-free versions could switch between two colors. All of the materials changed color quickly, taking less than two seconds to respond. They also maintained their color after the electrical power was turned off, making them practical for real-world applications.
Beyond changing color, the materials were also able to store electrical energy. The researchers tested them using a water-based electrolyte, which is safer and more environmentally friendly than many of the chemicals commonly used in energy-storage devices.
According to the researchers, this is the first time porphyrin-based polymer membranes have been used as electrochromic supercapacitors in a water-based system. An electrochromic supercapacitor is a device that can store energy while visibly changing color.
All three materials showed promising energy-storage performance, suggesting they could serve two functions at once: acting as both an energy-storage device and a smart color-changing surface.
The technology could have many future applications. One possibility is smart windows that automatically darken in bright sunlight while storing solar energy. Such windows could help reduce the need for air conditioning and lower building energy consumption.
Other potential uses include flexible electronics, wearable devices, smart clothing, chemical sensors, display technologies, anti-glare vehicle mirrors, aircraft windows, and even eyeglass lenses.
Because the materials are relatively inexpensive, easy to manufacture, and adaptable to flexible surfaces, researchers believe they could play an important role in the next generation of energy-efficient technologies.
