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Solar Cell Science Popular Series - Power Principle Articles
- Dec 04, 2017 -

Solar photovoltaic power generation generally refers to the use of semiconductors to convert light energy directly into electrical energy in the form of an energy source. Crystalline silicon solar cells are the most common form of solar cells originated in 1839, Becquerel, France was the first to discover the phenomenon of liquid electrolyte photovoltaic phenomenon of scientists. The general structure shown in Figure, infiltration in the silicon base shedding atoms, they will produce holes. In the same way, after the phosphorus atoms are doped into the matrix silicon, the outermost layer of the phosphorus atoms is a special structure with five electrons compared with the silicon atoms, which is more than that of the four-electron structure of silicon atoms An electron has become very active, called N-type semiconductor. Crystalline silicon solar cells are mainly made of silicon semiconductor material as a substrate made of a large area of the plane PN junction, that is about 15 cm × 15 cm in size P-type silicon by diffusion furnace proliferation of phosphorus atoms, the proliferation of a layer Thin, heavily doped n-type layer. Then, etching reaches PECVD to coat an entire surface of the N-type layer with an antireflection film to reduce the reflection loss of sunlight, so that the screen prints the metal gate lines on the diffusion surface as the front contact electrode of the solar cell. The metal film is printed on the etched surface, ohmic contacts the electrode as the backside of the solar cell, and the package is sintered.
When energetic photons strike a solar cell, many new electron-hole pairs are generated. Because the continuous absorption of the battery material led to the incident light intensity decreases, so along the incident direction, the density of electron-hole pairs within the cell gradually decreases in the concentration difference between the electron-hole pairs toward the interior of the cell to do Diffusion movement. When the electron-hole pair diffuses and reaches the PN junction limit, it will be split under the action of the built-in electric field and holes and electrons will be forced to P and N regions. If the circuit is in the open circuit , Then these photo-generated electrons and holes will accumulate around the P and N regions, respectively, and the P region will get an additional positive charge. Similarly, the N region will have an additional negative charge, and the accumulated positive and negative charges of the P and N regions It will have a photogenic electromotive force on the PN junction, if the solar cell connected to the positive and negative electrodes will form a current. PN junction at this time will be formed by the N-point to the P region of the photo-generated current.

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