This study reports the synthesis, characterization and photophysical properties of imine-linked receptors decorated ZnO nanoparticles using wet precipitation method. Initially, polymer dye 3 was synthesized usingcondensation reaction between 2-furancarboxaldehyde 1 and polyethylenimine 2. The decoration of imine-linked receptors on ZnO nanoparticles (sample A) was characterized and investigated by X-ray diffraction, scanning electronmicroscope and dynamic light scattering spectroscopic studies. Further, polymer dye 3 was added to ruthenium chloride (RuCl$_3$) to form a polymer–ruthenium-based composite dye-capped ZnO nanoparticles (sample B).The optical properties of sample A were evaluated by fluorescence and UV–Vis spectroscopy. The samples A and B were further processed to dye-sensitized solar cells using wet precipitation method. The results of observationsrevealed that the addition of ruthenium–polymer dye molecules increased the light harvesting capacity of ZnO-based DSSCs. A maximum solar power to electricity conversion efficiency ($\eta$) of 3.83% was recorded for sample B-based DSSCs with ruthenium–metal complex dye as a good photosensitizer. The recorded photovoltaic efficiency of sample B-based DSSCs was enhanced by 1.36% compared to sample A-based DSSCs.

ZnO nanoparticles (NPs) are used in optics, electronics, sensing, lasers, photocatalysis devices, etc. These applications are morphology as well as size dependent, which can be tailored by surface directing agents. In this study, we have investigated the effect of 4 tripodal ligands bearing urea/thiourea group, i.e., 1, 2, 3 and 4, on the morphology of surface-modified ZnO NPs, i.e., 1Z, 2Z, 3Z and 4Z, respectively, synthesized at room temperature (30–40°C) under alkaline conditions. Ligands are used to obtain surface-modified ZnO with various morphologies at room temperature. Extended hexagonal nanorods (${\sim}$2–3 ${\mu}$m length and ${\sim}$400 nm breadth), layered (flakes self-assemble to form a layered structure), polydisperse disk shaped [micron-sized (2–3 ${\mu}$m) and nano-sized (300–400 nm) particles and nanorods (1–1.5 ${\mu}$m length and 130–165 nm breadth) like morphology are observed for 1Z, 2Z, 3Z and 4Z, respectively. 1Z nanorods have sharp ends, while 4Z nanorods have semi-circular ends. Photocatalytic studies of these surface-modified ZnO NPs have been evaluated by Rhodamine B dye degradation.