Deeply etched laser texturing for enhancement of optical absorption in p-type silicon solar cells

Abstract

Structural design with high light absorption is a major challenge for thin silicon solar cells. Thin silicon solar cells acquire incomplete incident light absorption because the bandgap inadvertently has incomplete light absorption due to the indirect bandgap. The deeply etched micro-texture structure or deep scratch laser micro-texture (DELMS) in the cell architecture absorbs all visible light and collects electron-hole-generated photos to increase the efficiency of the solar cell. DELMS is designed using a simple and nontoxic fabrication method to form the texture of deep scratch surfaces. The front and back wafer surfaces are scratched due to laser radiation forming a range of microtextured with different width depths and crystallographic defects. The crystallographic defects resulting from laser radiation were modified using chemicals for the post-texture process. Silicon dioxide was deposited thermally on the surface of the wafer as an antireflection coating (ARC). The cell structure was analysed using SILVACO simulation based on the experimental data of the transmitter layer produced by phosphoric acid using the doctor blade method. The doctor blade method dispersed at a safe temperature of 875 °C for 30min was selected based on the optimal characterization of dopant densities greater than 1019cm-3. Next, the back surface field (BSF) was generated by Aluminium paste, while the front structure was generated by Argentum paste dispersed at 750 °C for 60 seconds. The diffusion lengths for planar and laser surface textures are 209.14μm and 278.00μm. The increase was about 32.94% for the laser surface texture compared to the plane surface. Meanwhile, the lifespan of the minority carrier for planar and laser surface textures is about 16.20μs and 28.60μs. The deep laser engraved texture showed an increase in the lifetime of about 76.54% compared to plane surface silicon solar cells. Moreover, light current-voltage (LIV) measurements showed the microtexture of deep laser scratches increased by about 10.00% compared to conventional planar fabrication processes for silicon solar cells. Thus, modifications to the wafer texture have the ability to increase the conversion efficiency through a deep laser scratch micro-textured that enables internal dispersion and increases the optical path length in the sidewall of the silicon solar cell.