Organic Photosynthetic Solar Cells Over Silicon Solar Cells
As the great spectre of climate change continues to loom large over the future, the search for viable, renewable energy sources is becoming ever more important.
Solar power has long been seen as a vital ingredient in our clean energy future. With a little inspiration from nature, solar power might just have become an even more promising prospect than was first thought.
Photosynthesis is the solar energy storage process in which plants take sunlight, carbon dioxide and water and convert these into energy (in the form of sugar) and oxygen. The traditional view of photosynthesis is that long-wavelength light (far-red and infrared light, with wavelengths longer than 700 nanometres) contains low energy photons. We used to think that light at these long wavelengths wasn’t “energetic” enough to produce oxygen. In other words, we thought photosynthesis could only occur with the light we humans can see.
But the discovery of a new type of chlorophyll – called Chl f – changes the way we think about photosynthesis. This new green molecule has the greatest ability of any cholorophyll to absorb red-shifted light – that is, light with wavelengths longer than the human eye can detect. This discovery of chlorophyll f challenges traditional views about the physical limits of photosynthesis.
Explicitly, the overall chemical equation for plant photosynthesis is given by the following equation:
In this double replacement reaction, complex compounds are synthesized from smaller ones. In this particular equation, hv represents the amount of energy from one photon, while the process known as electron transfer begins after the photosynthesis is complete. One way to increase the electron transfer of chlorophyll is to replace the Magnesium (Mg) atom with another metal such as Copper (Cu) or Iron (Fe). Though introduction of too much of heavy metal may cause damage to sensitive plant tissues, the outcome will surely be effective.
Organic Photosynthetic solar cells (PSC) are designed to convert light in to electricity in four steps, similar to that of the natural process. First the maximum absorption of light; which in turn forms an excited state of electrons as the second step. Next, the excitation diffusion into regions, where charge separation occurs and finally this then leads to charge transfer.
The typical characteristic of a photovoltaic device are described as-
This equation can be explained in the following terms: Io is the dark current, e is the charge of the electron, n is the diode ideality factor, U is the applied voltage, Rsh is considered the series resistance, Iph is the photoelectric current. The PSC can be synthesized into layers in following order-chlorophyll, a catalyst, argose, and graphene.
The ONE square inch prototype consists of light sensitive molecule, including the photosynthetic powerhouse chlorophyll, embedded in a water based gel sandwiched between Copper and plastic electrodes. Unlike traditionally, many of which contain toxic elements as Cadmium, biologically derived materials can be safely released into the environment after use. The cell’s flexibility could be made an ideal choice for covering irregular surfaces, large pieces could even be rolled up or folded for easy transportation.
It was estimated that the efficiency of a single solar cell produced from this method performed at less than 1% of that achieved by silicon cells. Although sensor data was unavailable, a current could be detected using an ohm meter. Even though this number is small, it does confirm the hypothesis that living chlorophyll can be extracted and used to transfer light energy into electrical energy.
However, varying the configuration of the cell, improved layering techniques, extracting chlorophyll from multiple sources and varying methods of extraction can be utilized to enhance the performance of a photosynthetic solar cell using chlorophyll. Hence as in the past solar panels and cells have replaced quite many electricity providing technologies in the past decade, now within a few years with the quest for better changes in lifestyle organic cells are sure to be on a rise.