What is a Solar Panel?

Sunlight is made up of energy particles called photons. Solar panels convert these photons into electricity that we can use to power our homes and electrical devices. Before solar panels were invented, solar energy was first used to create steam to drive machinery in factories. After the discovery of the photovoltaic effect in 1839, the first solar cell was created by Charles Fritts. Solar cells are used to create solar panels as we know them today.  The first main application of solar panels was for use in space satellites. Solar panels also made their appearance in calculators in the 1970s. These first generation solar panels were made from wafers of polycrystalline silicon. 

Newer, second generation solar panels are made up of several solar cells that are composed of amorphous silicon, cadmium telluride, gallium selenide, or gallium arsenide thin film layers. Solar panels are used to create clean energy from the sun. Sunlight photons are absorbed by the solar cell, which results in electrons becoming excited (creating negative charges) in the system. These electrons hit the surface of the solar panel and are knocked free to travel along the electric field in the direction of the current. The electrons can be converted into energy – which can be used to power things like light bulbs and more – before it returns to the solar cell.

What are Dye-Sensitized Solar Cells?

Third generation solar cells are among the newest emerging technologies including Dye-Sensitized Solar Cells (DSSCs). There are several advantages of DSSCs over traditional silicon solar cells, even though they have a lower energy conversion efficiency. DSSCs can operate under low light, can perform under higher temperatures, require less manufacturing energy, are easy to adjust its properties using eco-friendly materials, and can use a variety of substrates.

How did DSSCs come to be invented?

Well, the first report of the dye sensitized photovoltaic effect (generating an electric current from sunlight) was in 1877 by J. Moser. In 1960, the first wide band gap semiconductor (zinc oxide) with different dyes was discovered. A wide band semiconductor has 2 - 4 eV energy gap between the electron filled state (called the valence band) and the unoccupied band (called the conduction band). The wide band gap means that it needs a lot more energy to excite electrons than silicon does, which has a band gap of 1.1 eV. By changing the semiconductor, one can adjust the properties of the solar panel.

Titanium dioxide is a common wide band semiconductor used in DSSCs. The electrodes are made of a conducting glass to allow for electron flow. The working electrode (where the electrons get excited) is coated with titanium dioxide nanoparticles. The dye of choice is attached to the titania surface. The combination of the absorbed dye and titanium dioxide absorb photons from the sun to create excited electrons. The electrons travel along the circuit to the counter electrode. The electrolyte solution in between the electrodes balances the electrons on each side. DSSCs are a heavily-researched field, with the goal of increasing the solar energy conversion efficiency of DSSCs to become a more practical rival to the traditional silicon solar panels, which currently have a higher efficiency.

Summary

Solar panels are a booming renewable energy source that has been researched and modified since the 1800s. The solar panels you see on solar farms or on top of houses are second generation silicon solar panels, which currently have the highest energy efficiency. Current research on third generation solar cells like DSSCs and perovskites is being conducted in order to find alternative materials to build the solar panels and increase their efficiency.

References:

1. Advantages of DSSC: GCell. G24. (2014, July 17). Retrieved May 8, 2022, from https://gcell.com/dye-sensitized-solar-cells/advantages-of-dscc?msclkid=79786ecdcef911ecb372a81b680ecf51

2. Mbonyiryivuze, A. , Zongo, S. , Diallo, A. , Bertrand, S. , Minani, E. , Yadav, L. L. , Mwakikunga, B. , Dhlamini, S. M. , & Maaza, M. (2015). Titanium Dioxide Nanoparticles Biosynthesis for Dye Sensitized Solar Cells application: Review. Physics and Materials Chemistry, 3(1), 12-17.

3. Mr. Solar. (2022). How does a solar panel work? Retrieved May 8, 2022, from https://www.mrsolar.com/what-is-a-solar-panel/