Absorption and emission of porous silicon based on quantum dots models by TD-DFT: Experimental and theoretical approach

Abstract

In the present work, the relationship between experimental and theoretical analysis of optical properties of Si-nanostructures is presented. Coral-like luminescent porous silicon (p-Si) thin films were synthesized, and the main photoluminescence peak was found at around 690 nm. Infrared spectroscopy revealed mainly the presence of Si–H and Si–O bonds. The structural characterization determined an average nanocrystal size of 5.4 nm. A model based on Si quantum dots (QDs) with sizes ranging from 1.0 to 2.2 nm by TD-DFT (PBE/6-31G) in the Gaussian-16 package was used to simulate p-Si nanostructures. Equations were proposed for QD-like morphology of p-Si to calculate absorption/emission energies that fit with experimental data with high accuracy. The present research will help to predict the optical properties of complex and heterogeneous Si nanostructures.