The Study On The Crystalline Silicon Solar Cell With Nanostructure Surface

Reducing surface reflections is one of the effective ways to enhance the conversion efficiency of solar cells. The reflectance of multicrystalline silicon still reaches higher than20%after texturization by acid solution. Further suppressing reflections is important. The surface with nanostructure arrays which can be produced by laser etching, reactive ion etching, wet etching with metal assisted, has an excellent antireflection property. However, it does not work well for solar cell. How to change the advantage of nanostructure arrays into good electrical properties of solar cell is meaningful. In this thesis, the following work has been done:1. The nanohillocks with different height have been successfully fabricated by plasma immersion ion implantation (PIII) etching. The relationship between nanohillocks height and solar cell properties has been studied. It is found that the surface reflectance with nanohillocks is really very low over the wavelength from300-1100nm. Furthermore, as increasing the height of nanostructure, the reflectance becomes lower, whereas, surface recombination increases and the response in the short wavelength of solar cell worsen. When the height of nanohillocks is300nm, the conversion efficiency of the solar cell reaches the highest with the value of15.99%, as the compromise between reflectance and surface recombination.2. Acid etching with HF:HNO3=1:25has been applied to silicon wafer following PIII etching, and the relationship between solar cell properties and etching time has been investigated. The results indicate that acid etching not only remove damage layer but also optimize the nanostructure. And with increasing the etching time, surface reflectance increases. With the optimized etching time of20s, the conversion efficiency of the solar cell reaches as high as16.36%with short-circuit current of8.42A.3. Excellent surface passivation is especially vital for nanostructure arrays surface. We attempt to apply the silicon dioxide grown by liquid phase deposition to solar cell as passivation coating. The experimental results show that the silicon dioxide coating is more uniform when the concentration of fluosilicic acid is2.0M and without adding boric acid. Moreover, while the annealing temperature and annealing time is300℃and300s, respectively, the silicon dioxide coating has reached the best passivation effect and surface recombination velocity reduce from6923cm/s to2830cm/s.