Luminescent Si quantum dots in flexible and semitransparent membranes for photon down converting material

Abstract In this work, luminescent silicon quantum dots (Si-QDs) in flexible and semitransparent porous silicon-polymer hybrid materials exhibiting intense visible luminescence, observed with the naked eye, are reported. Si-QDs within free-standing porous silicon membranes (PSiM) were obtained and transferred to polyethylene terephthalate (PET) substrates and covered with polymetilacrylate (PMMA), all at room temperature. The effect of the thickness (2.46–13.36 μm) and porosity (79–85%) of the PSiM on their photoluminescence (PL) properties are analyzed. PSiM of 2.46 μm thickness shows the most intense PL emission, observed with the naked eye under UV excitation. The transmittance between 450 and 900 nm reduces only ∼4.9% from that one of the PET substrate when the porosity is about 85%. The size of the Si-QDs, analyzed by Raman spectroscopy, reduces from 4.58 to 3.10 nm when the porosity is increased from 79 to 85%, and as a consequence a PL blue-shift is observed. The PL property of the flexible PMMA/PSiM/PET structures remains stable and breaking strength after several cycles of bending at different angles. Therefore, this work provides an adequate method for the development of hybrid luminescent, flexible and stable PSiM structures for its application as a photon-down converting material.