Campus Moncloa
Campus of International Excellence
The Solar Cell of the Future is here
The Thin Films and Microelectronic research group from the UCM and the Solar Energy Institute at the UPM within the framework of the Global Change and New Energies cluster at the Moncloa Campus have successfully created the first silicon solar cell based on intermediate band materials that it has demonstrated how an IB solar cell works.
13/06/2012
The Thin Films and Microelectronic research group from the UCM and the Solar Energy Institute at the UPM within the framework of the Global Change and New Energies cluster at the Moncloa Campus have successfully created the first silicon solar cell based on intermediate band materials that it has demonstrated how an IB solar cell works.
The advances in energy field knowledge and the efficiency obtained from energy conversion has become the engine of today”™s technological society. It directly influences the economic and the social welfare system of a country.
The ways in which human species have obtained energy have seriously jeopardized their ecosystem and even their own species future. The current energy model uses mass energy consumption based on fossil fuels resources; this is totally incompatible with a sustainable development. Serious environmental problems such as acid rain, greenhouse gases emissions and climate change are the results of this unsustainable energy sources.
As exposed above, there are many reasons to improve basic energy and it seems to be that to use renewable energy would be the best route to succeed in the end. Therefore, researchers are focusing on solar energy: sun emits over the land surface an amount of energy six thousand times greater than the quantity estimated which would cover our needs of energy in 2020. In the 1980's, the engineer Roland Hulstrom, calculated that placing only three thousandths of the U.S landscape with photovoltaic panels (just 160 km square side) will generate enough electricity to supply the entire country. This points out that a solar energy power is virtually unlimited.
We are currently progressing in the development of third generation solar cells. Our goal is to obtain a better conversion efficiency of solar energy into electrical energy without incurring higher costs of production. The solar cell based on Intermediate Band (IB) material is an example of this third generation devices.
In this kind of solar cells, it will reach up to 60% of efficiency in the conversion versus the 22% in traditional silicon cells used currently. In order to make this happen, this device has the capacity to absorb a larger number of photons (energy particles from the sun) which then excite electrons (electric charge carriers particles) in the material. A traditional silicon solar cell only will use those photons that have enough energy to make the electron "jump". They ”œjump” from a state in which they are tightly bound to atoms of the material (valence band) to a higher energy one from where they will be afterwards collected to generate electric current (conduction band). Those photons with less energies won´t be able to make an electron "jump" and will be missed.
In spite of the fact that photons with a lower energy are usually missed, we have observed that in an IB solar cell an intermediate energy ”œstep” is created so this does not happen. This IB has the advantage that permits those electrons which receive less energy to reach the conduction band in two jumps instead of one (as occurs normally). A clear example to understand the concept of de IB is to imagine that big long puddle in our way. We must jump to get to the other side. If we have had a rock in the middle, it would be easier to reach the other side without getting wet by performing two jumps and probably needing lower energy to make the jump.
Author of the article: Eric García Hemme
Tag: Global Change and new Energies Source: CEI Campus Moncloa
Event date:
13/06/2012
Science Outreach Awards