Standard Deviation Quantitative Characterization and Process Optimization of the Pyramidal Texture of Monocrystalline Silicon Cells.

Zheng Fang,Fei Zhou,Shixiang Huang,Tao Jang,Zhilong Xu

doi:10.3390/ma13030564

Abstract

To quantitatively characterize the pyramidal texture of monocrystalline silicon cells and to optimize the parameters of the texturing process, the relative standard deviation Sh was proposed to quantitatively characterize the uniformity of the pyramidal texture. Referring to the definition and calculation of the standard deviation in mathematical statistics, Sh was defined as the standard deviation of the pyramid relative height hi after normalization of the pyramid height Hi of monocrystalline silicon wafer surfaces. Six different silicon cells, with different pyramidal textures, were obtained by applying different texturing times. The relationships between Sh and the photoelectric characteristics were analyzed. The feasibility of quantitatively characterizing the uniformity of the pyramidal texture using Sh was verified. By fitting the Sh curve, the feasibility of optimizing the texturing process parameters and predicting the photoelectric characteristics using Sh was verified. The experimental and analytical results indicate that, when the relative standard deviation Sh was smaller, the uniformity of the pyramidal texture obtained by texturing was better. The photoelectric conversion efficiency (PCE) of the silicon cells monotonically increased with decreasing Sh. The silicon cell obtained by texturing with 2% tetramethylammonium hydroxide (TMAH) solution for 18.1 min had a textured surface with a minimum of Sh, the reflectivity of the silicon cell reached its minimum value of 2.28%, and the PCE reached its maximum value of 19.76%.

Highlights

Silicon cells occupy approximately 90% of the worldwide market share in the photovoltaic (PV)industry, due to their low cost and high photoelectric conversion efficiency (PCE) [1]
The photoelectric conversion efficiency (PCE) of the silicon cells monotonically increased with decreasing Sh
The silicon cell obtained by texturing with 2% tetramethylammonium hydroxide (TMAH) solution for 18.1 min had a textured surface with a minimum of Sh, the reflectivity of the silicon cell reached its minimum value of 2.28%, and the PCE reached its maximum value of 19.76%

Summary

Introduction

Industry, due to their low cost and high photoelectric conversion efficiency (PCE) [1]. The PCE of a silicon cell can be improved in two basic ways: (1) Increasing its sunlight absorption rate and (2). A pyramidal trapping texture is directly prepared on the surface of a silicon wafer by chemical texturing, which can effectively improve the sunlight absorption rate, thereby improving the PCE [4,5,6,7]. Many reports on the influence of surface texture on the photoelectric properties of silicon cells have been presented. Kim et al studied the diffusion depth of different pyramidal textures and found that, compared to the other pyramidal textures, the uniform small pyramidal structure had more uniform diffusion, and Materials 2020, 13, 564; doi:10.3390/ma13030564 www.mdpi.com/journal/materials

Methods

Results

Conclusion