As global energy sources become more and more tense, solar energy is called new energy development, and we use more solar cells in our lives. The solar cell is based on semiconductor materials. After the photoelectric material absorbs light energy and photoelectric conversion occurs, so that it generates current, what is the working principle of the solar cell? A solar cell is a device that directly converts light energy into electrical energy through a photoelectric effect or a photochemical effect. When the sun shines on the semiconductor, some of it is reflected off the surface and the rest is absorbed or transmitted by the semiconductor. Some of the absorbed light, of course, becomes heat, while other photons collide with the valence electrons that make up the semiconductor, thus creating electron-hole pairs. In this way, light energy is converted into electrical energy in the form of electron-hole pairs.
The physical basis of solar cells
When the sunlight illuminates the pn junction, electrons in the semiconductor release electrons due to the acquisition of light energy, correspondingly electron-hole pairs are generated, and under the action of the barrier electric field, the electrons are driven toward the pattern region。 The holes are driven toward the P-type region, so that there are excess electrons in the region, and the P region has excess holes。 Thus, a photo-generated electric field opposite to the direction of the barrier electric field is formed in the vicinity of the p-n junction。
If there is a pn junction in the semiconductor, a barrier electric field is formed on both sides of the p-type and n-type interfaces, which can drive electrons to the N region and holes to the P region, so that there are excess electrons in the N region, and there is excess P region. The hole forms a generating electric field of light opposite to the direction of the electric field of the barrier near the PN junction.
There are more than a dozen semiconductor materials for manufacturing solar cells, and thus there are many types of solar cells。 At present, the most mature and commercially valuable solar cells are silicon solar cells。 Below we take silicon solar cells as an example to introduce the working principle of solar cells in detail。