The structural, optical and electrical properties of sodium titanate nanotubes sensitized with nitrogen/sulfur co-doped graphene quantum dots as potential materials for quantum dots sensitized solar cells

Abstract

In this work, we present the synthesis of nanoscale heterostructures of sodium titanate nanotubes Na₂Ti₂O₅.H₂O (NaNT) decorated with N- and S- co-doped graphene quantum dots (NS-GQD) for quantum dots sensitized solar cells (QDSSC). The study was mainly focused on the structural, microstructural, electrical and optical characterization of these nanoscale heterostructures by means of X ray diffraction, transmission electron microscopy, atomic force microscopy, Raman, UV–vis and impedance spectroscopies. Our nanoscale heterostructures yielded a significant enhancement in the electric conductivity interpreted in terms of favorable interactions between the NS-GQD and the NaNT acting as proper connectors. Finally, our QDSSC prototype exhibits promising values for diffusion coefficient and recombination times as evidenced by means of impedance modulated photocurrent and photovoltage spectroscopies. Also, we consider that these materials could be further explored for electron transport layers applications in order to exploit the advantages regarding electron transport properties.