Hexagon shaped mesoporous Zinc oxide nanodisks (ZnO NDs) with exposed ± {0001} polar facets have been synthesized by using ethyl cellulose (EC) and cetrimonium bromide (CTAB) as the capping and structure directing agents. We have characterized ZnO NDs using analytical techniques, such as powder X-Ray diffraction (PXRD), diffuse reflectance UV-Visible (UV-Vis) spectroscopy, photoluminescence (PL) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis and proposed a plausible mechanism for the formation of ZnO NDs. EC molecules forms a colloidal solution in 1-butanol: water (3:1) solvent system having a negative zeta potential (ζ ≈ - 32 mV) value which can inhibit CTAB assisted c-axis growth of ZnO crystal and encourage the formation of ZnO NDs. The reactions carried out in presence of only CTAB and only EC, formation of hexagonal ZnO nanorods (NRs) and ZnO nanosheets (NSs) composed of numerous ZnO nanoparticles are observed respectively. Photovoltaic properties of ZnO NDs as compared to ZnO NRs, ZnO NSs and conventional ZnO nanoparticles (NPs) are investigated by co-sensitizing with CdS/CdSe quantum dots (QDs). An ~35% increase in power conversion efficiency (PCE, η) is observed in ZnO NDs (η≈ 4.86%) as compared to ZnO NPs (η ≈3.14 %) while the values of PCE for ZnO NR and ZnO NS based devices are found to be ~2.52 % and ~1.64 % respectively. Enhanced photovoltaic performance of the ZnO NDs based solar cell is attributed to an efficient charge separation and collection, boosted by the exposed ±(0001) facets apart from the single crystalline nature, better light-scattering effects and high BET surface area for sensitizer particle adsorption. Electrochemical impedance spectroscopy (EIS) analysis further reveals that the charge recombination resistance and photo-induced electron lifetime are substantially higher in ZnO ND based device than the ZnO NR, ZnO NP and ZnO NS based devices, which demonstrates slower electron-hole (e− - h+) recombination rate and faster charge migration through the single crystalline ZnO NDs.