The solar cell, otherwise known as the photovoltaic cell, is currently one of the most energy-efficient devices to collect power in the modern era. However, it is only one of the most expensive, due to the fact that the materials needed to build a solar cell have expensive price tags on the market. While it remained a very expensive electrical device in the 2000s, it eventually became cheaper and cheaper thanks to the multiple research studies conducted to find ways to reduce the price of solar cells, which could be achieved either by finding cheap alternative materials or by producing the expensive materials in a much less expensive way. One important study for the latter was conducted by Daniel Morse, a molecular biochemist at the University of California, in 2006. To know more about Morse’s research, here is the amazing origin of sea sponge-inspired solar cells.
Origins of the Sea Sponge-Inspired Solar Cell
Before we get into the development of Morse’s solar cell in 2009, let us first discuss the animal that inspired the biomimetic invention. The orange puffball sponge, also known as the golf ball sponge and its scientific name “Tethyaaurantium,” is a species of sea sponge that belong to the family Tethydae under the phylum Porifera, and it is found in the North-Eastern Atlantic Ocean, the Mediterranean Sea, and in the shallow reefs of Southern Africa. This specific sponge got its most popular because of its color (yellow-orange), shape (spherical), and appearance (looks like a puffy ball at first glance). While the name implies that it is harmless in the sea, the orange puffball sponge actually has sharp protruding spicules or tiny spikes that would cause skin irritation on humans.
The orange puffball sponge is able to produce these spicules by releasing enzymes in the water, and then it would collect silicon and calcium to create the spicules with the help of a special kind of protein in its body. The special protein is also responsible for organizing the molecules of the sponge and allows it to have structural integrity in the sea.
As for solar cells, they basically consist of the materials and chemicals found in the spicules of the orange puffball sponge, and through this connection, Daniel Morse tried to find ways to replicate the sponge’s process of building its spicules and utilize it to make the production of the expensive solar cell materials cheaper. Before Morse’s research, the production of solar cells involves several painstaking processes, including vapor deposition (wherein chemicals are forced to settle on an inert surface,” change in high temperature, and control of low pressure. Because of these processes, making a single solar cell can be quite expensive. The most expensive process in the creation of solar cells is arguably the vapor deposition, which is needed in order to produce a layer of crystalline semiconductor that absorbs solar energy.
In the research paper, Morse stated that orange puffball sponges have a unique way of creating the layer of silica (an important material for the solar cell’s semiconductor) without the need to go through other processes that are utilized in manufacturing solar cells, such as the material’s subjection to high temperature and low temperature. By copying the sponge’s natural process of producing silica, Morse said that he could create a biomimetic technology that shortens the process of building solar cells. In addition, the technology would keep the manufacturing costs down, and the production would also require less energy.
For the creation of Morse’s solar cell, they used a mixture of aqueous zinc nitrate and silicatein with ammonia instead of seawater in order to have a synthetic breakdown of the zinc nitrate into a crystallized form of zinc oxide. During the process, the researchers have regulated the rate of how much ammonia they should diffuse into the zinc nitrate mixture, and because of the regulation, the zinc nitrate had a faster process of transforming into crystalline layers that can be used as semiconductors for solar cells. In the tests, they were able to produce multiple layers of crystallized zinc oxide that are 100 to 300 nanometers thick. These layers were then shown during a meeting with the American Chemical Society in 2006.
A few years later, Morse’s technology was utilized to build cheaper solar cells, thus resulting in a decrease in the device’s price on the market. Today, the number of research studies on orange puffball sponges is still increasing, as scientists believe that the weird sponge still hides secrets that can help us understand sea life. One of the most recent studies conducted on the sponge is its ability to not buckle under pressure despite its relatively small size and minimal weight. In the future, researchers hope that the anti-buckling ability of orange puffball sponges can be utilized to strengthen man-made materials.