Photoluminescence of Cu2O nanostructured in stressed thin films induced by temperature

• Published in: Journal of luminescence 2019-11, Vol.215, p.116642, Article 116642
• Main Authors: Martínez-Saucedo, G., Torres-Castanedo, C.G., Arias-Cerón, S., Castanedo-Pérez, R., Torres-Delgado, G., Zelaya-Ángel, O.
• Format: Article
• Language: English
• Subjects: Cu2O thermal expansion coefficient; Cu2O thin films; Dip coating; Excitons; Low-T photoluminescence; Stressed films
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2019.116642

Cu2O nanostructured films were prepared by the dip-coating method with average crystallite size of 10 ± 1 nm. The photoluminescence of Cu2O was studied for different temperatures in the 70–300 K interval. The range of wavelengths analyzed was 360–1000 nm. Two photoluminescence systems were used, with an excitation line of 325 nm He–Cd and 488 nm Ar laser, at different power. Several interband and excitonic transitions at energies in the 1.8–2.8 eV interval were identified for Cu2O where an intensity shift toward lower energies was observed as the temperature was increased. The difference of the thermal expansion coefficients (α) between the Cu2O and the soda-lime substrate induces change from compressive to tensile stress within the 70–300 K interval. This change is a consequence that α value for Cu2O is negative and for soda lime is positive in that temperature region. Raman spectra as a function of temperature, show a frequency shift for all modes studied and α values of thin film Cu2O were estimated from these shifts at 77 and 280 K. The stress (σ) on the Cu2O film was calculated considering the decrease of the temperature in this interval. The effect of this stress on the energy band structure is related to the shift of the PL bands. •Photoluminescence of Cu2O nanostructured-thin-film in the 1.8 to 2.8 eV range.•Anomalous behavior of low-T photoluminescence emissions of stressed Cu2O films.•Thermal properties of Cu2O film and substrate affect the luminescence of the film.•Thermal expansion coefficient of Cu2O film is calculated from Raman spectroscopy.