Study on the Fermi level of microstructured Silicon with impurities introduced by chalcogenides and their affect on solar cell efficiency

TL;DR

This paper investigates how impurities introduced by chalcogenides affect the Fermi level in microstructured Silicon and explores their impact on the efficiency of intermediate band solar cells using theoretical models.

Contribution

It establishes impurity energy levels in microstructured Silicon post-annealing and analyzes their influence on Fermi level and solar cell efficiency.

Findings

Impurity levels of sulfur and oxygen in microstructured Silicon are characterized.

The relationship between Fermi level, impurity density, and temperature is modeled.

Theoretical efficiency limits of IBSC based on microstructured Silicon are discussed.

Abstract

Microstructured Silicon, which is obtained by irradiating the surface of a Silicon wafer with femtosecond laser pulses under certain circumstances, has unusual optical properties such as the strong absorption of light with wavelength from 0.25{\mu}m to 17{\mu}m. So it holds great promise in the intermediate band solar cell (IBSC). Some articles have discussed the electronic structure associating with simple substitutional impurities in Silicon introduced by chalcogenides. And on this basis, after high temperature annealing treatment, we establish the mode of impurity levels of microstructured Silicon introduced by sulfur and oxygen. Using generalized statistics of multi-level,we analyze the probability of electronic in all local energy levels and the relationship among Fermi level, temperature and the density of impurities. Then the theoretical conversion efficiency of the corresponding IBSC is discussed with the Detailed Balance Theory. And the issue of making high efficiency solar cells based on femtosecond laser microstructured Silicon is discussed in detail.