Charge transport on vertically aligned ZnO nanorods with different aspect ratios

BENAVENTE LLORENTE, VICTORIA; VÁZQUEZ, CECILIA I.; BURGOS, MAXI A.; BARUZZI, ANA M.; IGLESIAS, RODRIGO A.

ELECTROCHIMICA ACTA

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2019 vol. 319 p. 990 - 997

0013-4686

Zinc Oxide is a semiconductor widely used in sensitized solar cells as an electron transport layer. Amongthe different nanostructures obtainable for this material, the vertically-aligned ZnO nanorods are of greatinterest for the design of photoanodes; mainly due to the directionality of charge transport. Vertically-aligned ZnO nanorods of different aspect ratios were prepared via hydrothermal synthesis. UVeVisabsorption was used to determine the dependence of the optical band gap energy on the nanoroddiameter according to the Burstein-Moss shift theory due to the presence of surface states. Informationabout the electronic properties of the different nanorods was obtained by spectroelectrochemicalmeasurements used to monitor the absorbance decrease and Egap shift at different potentials. Time offlight photocurrent transients indicated a dependence on charge transport time with ZnO nanorodlength. All evidences point to a large distribution of trap states located in the semiconductor band gap.