Understanding the effects of picosecond laser texturing of silicon solar cells on optical and electrical properties

摘要

Surfaces of silicon-based solar cells are modified to reduce reflectivity and enhance the absorption of light. Texturing using ultra fast lasers is a potential technique for surface modification of solar cells. In order to fabricate superior surfaces with low reflectivity and optimised electrical performance, it is essential to understand the impact of texture characteristics. In this work, two dimensional surface textures were fabricated on silicon surface using a picosecond laser operated at different laser parameters and the reflectance was measured. The experimental data was used to identify the set of optimal laser parameters and dimensions of surface structures to minimise the surface reflectivity of silicon. The height of the structures obtained were around 10 μm with a spacing of 25 to 30 μm. As a result, a wave-like profile was generated, which can enhance the absorption of photons on the surface and hence reduce reflectivity. Using this technique, the surface reflectivity was reduced to as low as 6. In addition, the electrical behaviour of the textured surface was simulated using finite-difference time-domain (FDTD) method. The simulated results of current density and power generation suggest that rectangular-shaped gratings have higher current density and power as compared to those obtained for wave-like gratings.