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 εc of only about 1.13% with a saturated crack density ρs 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 εc was observed. AlN layers deposited at higher discharge powers yielded higher fracture energy and exhibited better performance in terms of εc and ρs.