1D/2D mixed nanocomposite thin film of SnO2 /carbon nanotube/graphene

Tin oxide (SnO2) has gained much attention in various fields such as optoelectronic industries and gas sensors. SnO2 thin films have been extensively used as electron transport layers (ETL) in planar perovskite solar cells due to their high stability, good processability, and appropriate band alignment. However, it suffers from relatively low charge mobility. Although there were some successful attempts to improve the charge mobility of SnO2 thin films by incorporating carbon nanotubes (CNT) or graphene in its structure, simultaneous addition of these 1D/2D mixed nanostructures in SnO2, which can lead to far better optoelectronic properties has never been reported. 1D/2D mixed nanocomposite thin films based on SnO2/CNT/graphene are successfully synthesized in this research, and the structural, morphological, and optoelectrical properties of the films are investigated. For this purpose, SnO2 sols were prepared by dissolving and refluxing SnCl2.2H2O in 1-propanol at 87 °C for 2 h. In order to synthesize nanocomposite samples, various amounts of CNT and/or graphene were added to the solution prior to refluxing. The films were deposited by dip coating and subsequently calcined at 180 °C. The thin films were studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV-Vis spectroscopy. The XRD results confirm the formation of the SnO2 phase. FESEM images thoroughly demonstrate the presence of CNTs and graphene beside SnO2 nanoparticles. The absorbance of the films as well as their band gaps are remained almost constant after CNT/graphene addition.