Benzo[ghi]perylene monoimide based photosensitive lamellar Cd-doped ZnO nanohybrids

Abstract

Lamellar hybrid inorganic/organic nanostructures comprising of alternating layers of benzo[ghi]perylene monoimide and Cd-doped ZnO called BPyM/CZO nanohybrids have been synthesized electrochemically on Ga-doped ZnO/Si. In order to study the effect of organic surfactant, inorganic CZO nanorods have also been electrochemically synthesized. The role of annealing and organic surfactant on morphology, structure, composition and opto-electronic properties is analyzed. The nanohybrids and nanorods are c-axis oriented preferentially with their (002) direction perpendicular to the substrate surface. Annealed BPyM/CZO nanohybrids show visible orange photoluminescence emission while unannealed nanohybrids and inorganic CZO nanorods emit white emission at room temperature. The annealed nanohybrids and inorganic nanorods tend to follow the Varshni equation with temperature variation from 80 K to 300 K. Spectroscopic ellipsometry reveals the thickness, refractive index and band gap of the nanostructures. Annealing tends to expand the band gap by 50 meV in the case of inorganic CZO nanorods, but shrinks the band gap by 20 meV for BPyM/CZO nanohybrids. Temperature dependent photosensitivity measurements reveal that BPyM/CZO nanohybrids are highly photosensitive, ∼8 fold and ∼4 fold higher than inorganic CZO nanorods at 80 K and 300 K, respectively. The studies indicate that BPyM/CZO nanohybrids hold potential as photosensors.