Highly photoluminescent polymer films deposited on glass and flexible substrates based on partially oxidized silicon nanocrystals

In this work, optical properties of Silicon (Si) Oxide powders with Si nanocrystals (Si-nCs) embedded in a polymeric matrix (polymethyl methacrylate-PMMA) on BK7 glass and flexible substrates (acetate) are reported. The Si oxide powders were exfoliated from porous silicon layers (PSLs) with porosities of 57–98.3% obtained at 65 mA. The PSLs were obtained by electrochemical etching using, Si p-type (110), ρ=0.25-0.6 Ω-cm. For this, current densities of 65 mA and 35 mA were used with hydrofluoric acid and ethanol solution (Hf:EtOH) in (3:1), (1:3), (1:2), and (1:1) proportions respectively. To passivate and preserve the Photoluminescence (PL), the Si-oxide powders collected from exfoliation of PSLs were immersed at the polymeric matrix and deposited on acetate and BK7 glass substrates by spin-coating method. The PSLs were characterized by Photoluminescence (PL), Scanning Electron Microscopy (SEM) and X-ray spectroscopy (EDS). Subsequently, Si-oxide powders as a polymeric film exhibited strong PL emission either on acetate or on BK7 glass substrates, for which samples were characterized by PL and Raman measurements. The presence of oxidized Si-nCs were detected by Raman measurements, with average sizes between 1 to 1.5 nm, creating radiative defects (Si=O) that could be responsible of PL. The PSLs PL emission maximum position remained almost at the same wavelength even after when it is deposited on the polymer. In this manner, oxidized Si-nCs serve as effective passivating agents for PL. • SiOPF films were obtained from exfoliated PSLs and transferred onto BK7 and acetate substrates. • SiOPF exhibit PL emission in the 550–700 nm range, and their PL intensity depends on oxygen content and the initial PSLs porosity. • Raman analysis confirms oxidized Si–nCs with crystal sizes of 1–1.5 nm. • A blue shift in PL emission is observed in the SiOPF/BK7 and SiOPF/acetate samples as the oxygen concentration increases.