Disorder and Confinement Effects to Tune the Optical Properties of Amino Acid Doped Cu2O Crystals

Biominerals are organic-inorganic nanocomposites exhibiting remarkable properties due to their unique configuration. Using optical spectroscopy and theoretical modeling, it is shown that the optical properties of a model bioinspired system, an inorganic semiconductor host (Cu2O) grown in the presence of amino acids (AAs), are strongly influenced by the latter. The absorption and photoluminescence excitation spectra of Cu2O-AAs blue-shift with growing AA content, indicating band gap widening. This is attributed to the void-induced quantum confinement effects. Surprisingly, no such shift occurs in the emission spectra. The theoretical model, assuming an inhomogeneous AA distribution within Cu2O-AAs due to compositional disorder, explains the deviating behavior of the photoluminescence. The model predicts that the potential causing the confinement effects becomes a function of the local AA density. It results in a Gaussian band gap distribution that shapes the optical properties of Cu2O-AAs. Imitating and harnessing the process of biomineralization can pave the way toward new functional materials.

Automated summary

This study investigates the optical properties of a bioinspired system, Cu2O-AAs, using optical spectroscopy and theoretical modeling. The presence of amino acids strongly influences the absorption and photoluminescence excitation spectra of Cu2O-AAs, resulting in a blue-shift and wider band gap due to quantum confinement effects. Surprisingly, no such shift is observed in the emission spectra, which can be explained by the inhomogeneous distribution of amino acids within Cu2O-AAs predicted by the theoretical model.