Photoelectric effect

Marangelí Acevedo Castro

Recently in physics class we discussed the photoelectric effect developed by Albert Einstein. This photoelectric effect consists of a metal with one valence electron which is released when a photon has the enough energy to release it when is irradiated by an electromagnetic radiation, which usually is UV light. Then all valence electrons emitted by all the atoms of the metal are used as current. The photoelectric effect has a lot of uses like sensors, spectroscopy and solar cells among others.

I asked myself what if instead of using a metal with one electron in its valence shell, use a metal with two valence electrons? Or what if we can irradiate more UV light to a solar cell and not only the one emitted by the sun? Probably it would be more difficult for the electrons to be released because they will have more attraction or force between them making it more difficult to be released by the atom. If this was possible, assuming there is no attraction between the two valence electrons, a solar cell could generate, in theory, double the current a normal cell would with a metal with only one valence electron. The photons causing the release of the valence electron will need to generate more energy in order to excite the electrons and produce the current. I believe that the UV light emitted by the sun will not be sufficient to generate the amount of energy needed for the electron release. This is why I asked myself the second question mentioned before. 

I read that if the light intensity is increased, this will increase the number of the photons and therefor it will be easier to release more valence electrons from the metal in the cell. After knowing this I wondered if maybe increasing the light intensity we could release the two valence electrons in the metal. In the course of physics we also learned that when a mirror is irradiated by an incident ray it is reflected with the same angle of incidence but it takes another direction unless the angle is perpendicular to the surface of the mirror. This law of reflection varies depending if the surface of the mirror is flat or with a curvature. Knowing this I thought that placing specific mirrors around the solar cell could be useful to generate more light intensity for the electron emission. Examples of metals with two electrons in the valence shield are zinc, copper, nickel and iron, among others. In my opinion I think a solar cell that could generate more current will be great for the electricity used in a house; saving energy, money and helping the environment.