AlN passivation layer-mediated improvement in tensile failure of ZnO:Al thin films on polyethersulfone substrates is investigated. ZnO:Al films without any passivation layer were brittle with a crack-initiating bending strain ε_c of only about 1.13% with a saturated crack density ρ_s of 0.10 μm⁻¹ and a fracture energy Γ of 49.6 J m⁻². On passivation by an AlN overlayer, the fracture energy of the system increased considerably and a corresponding improvement in ε_c was observed. AlN layers deposited at higher discharge powers yielded higher fracture energy and exhibited better performance in terms of ε_c and ρ_s.