Résumé: Abstract Transparent conductive oxides face critical challenges in simultaneously optimizing electrical conductivity and optical transparency for advanced optoelectronic applications. Zinc oxide (ZnO) and aluminum-doped zinc oxide (Al-ZnO) thin films are extensively studied for their optoelectronic applications due to their excellent transparency (> 85% in visible region) and electrical conductivity. This study presents novel advancements in controlling structural and optical properties through Al doping (0–3 at.%) via RF magnetron sputtering, demonstrating:(1) non-linear enhancement of crystallinity with a 93.7% increase in crystallite size (25.15 nm undoped to 48.72 nm at 3 at.% Al) and 73.4% reduction in dislocation density (1.581× 10 15 to 0.421× 10 15 lines/m 2);(2) emergence of unique acicular morphology with 22% greater surface area at 3 at.% Al;(3) precise ar tuning from 3.131 eV to 2.796 eV while maintaining high transmittance; and (4) comprehensive characterization including Raman spectroscopy showing E₂ (high) mode shifts from 437 cm⁻ 1 to 433 cm⁻ 1 with doping, XPS confirming Al 3⁺ incorporation at 73.8 eV binding energy, and BET analysis revealing increased surface area from 320 m 2/g to 380 m 2/g with enhanced mesoporous (65% of total volume) and microporous (15% increase) characteristics. The work reveals three key innovations:(1) identification of optimal 2 at.% Al doping concentration that maximizes both crystallinity (32.92 nm crystallites) and optical performance (2.94 eV bandgap);(2) discovery of competing size-strain effects enabling simultaneous property enhancement; and (3) development of reproducible bandgap engineering process. The specific objectives were to synthesize pure and Al-doped ZnO films (0, 2, and 3 at.%) using RF magnetron sputtering and characterize them using X-ray diffraction (XRD), surface morphology analysis with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), UV–visible spectroscopy, Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Surface Area and Porosity Analysis. XRD analysis revealed all films exhibited polycrystalline wurtzite structure with preferential c-axis orientation. SEM demonstrated a morphological transition from hexagonal grains (undoped) to acicular structures (3 at.% Al). Optical characterization confirmed high transmittance (> 85%) and bandgap reduction from 3.131 eV (undoped) to 2.796 eV (3 at.% Al). These results demonstrate that 2 at.% Al-doped films achieve optimal balance between structural perfection (32.92 nm crystallites, 0.922× 10 15 lines/m 2 dislocation density) and optical functionality (2.94 eV band gap,> 85% transmittance), making them ideal for transparent conductive oxides in LEDs and solar cells. The quantitative correlations established enable precise engineering of doped ZnO systems for optoelectronic applications.