1. Material band width:
The open circuit voltage UOC increases as the band width Eg increases, but on the other hand, the short circuit current density decreases as the band width Eg increases. As a result, it may be desirable to have a peak in solar cell efficiency at a certain Eg. Solar cells are made from materials with an Eg value of 1.21.6 eV, which is expected to achieve maximum efficiency. Thin-film semiconductors are preferred for direct bandgap semiconductors, which absorb photons near the surface.
2. Temperature:
The diffusion length of the minority has slightly increased with the increase of temperature, so the photo-generated current also increases with the increase of temperature, but UOC decreases sharply with the increase of temperature. The fill factor decreases, so the conversion efficiency decreases with increasing temperature.
3. Irradiance:
As the irradiance increases, the short-circuit current increases linearly and the maximum power increases. Focusing the sun on the solar cell allows a small solar cell to generate a lot of power.
4. Doping concentration:
Another factor that has a significant impact on UOC is the semiconductor doping concentration. The higher the doping concentration, the higher the UOC. However, when the impurity concentration in silicon is higher than 1018/cm3, it is called high doping. The band gap shrinkage due to high doping, the incomplete ionization of impurities, and the decrease in lifetime are collectively referred to as high doping effects, and should also be avoided. .
5. Photogenerated carrier composite life:
For semiconductors of solar cells, the longer the composite lifetime of photogenerated carriers, the greater the short circuit current. The key to achieving long life is to avoid the formation of recombination centers during material preparation and battery production. During the processing, appropriate and often the relevant process treatment can remove the composite center and extend the life.
6. Surface recombination rate:
Low surface recombination rates help to increase Isc, and the recombination rate of the front surface is difficult to measure. It is often assumed that an infinite type of battery called back-field (BSF) is designed to diffuse the back of the cell before depositing metal contacts. A layer of P+ additional layer.
7. Series resistors and metal grid lines:
The series resistance is derived from the lead, metal contact grid or battery body resistance, while the metal grid line is not transparent to sunlight. In order to maximize the Isc, the area occupied by the metal gate line should be minimized. Generally, the metal grid lines are made into a dense and thin shape, which can reduce the series resistance and increase the light transmission area of the battery.
8. Use suede battery design and select high quality anti-reflection film:
Relying on the surface pyramidal pyramid structure, multiple reflections of light not only reduce the reflection loss, but also change the direction of advancement in the optical silicon and extend the optical path, increasing the yield of photogenerated carriers; The area of the PN junction is increased to increase the collection rate of photo-generated carriers, increase the short-circuit current by 5% to 10%, and improve the red light response of the battery.
9. The effect of shadows on solar cells:
The solar cell will be unevenly illuminated due to shadow blocking, etc., and the output power is greatly reduced.
At present, the application of solar cells has entered the industrial, commercial, agricultural, communications, and public utilities sectors from the military and aerospace sectors. In particular, it can be used in remote areas, mountains, deserts, islands, and rural areas to save expensive prices. Transmission line. But at the current stage, its cost is still very high. It takes tens of thousands of dollars to send 1kW of electricity, so large-scale use is still subject to economic constraints.
However, in the long run, with the improvement of solar cell manufacturing technology and the invention of new optical-electrical conversion devices, the protection of the environment and the huge demand for regenerative clean energy, solar cells will still be compared with solar radiation. The method of cutting can open up broad prospects for the future use of solar energy by human beings on a large scale.