a quantum dot-polymer composite comprising a polymer host matrix and a plurality of quantum dots dispersed in the polymer host matrix; and

a barrier film disposed on at least a portion of surface of the quantum dot-polymer composite,

wherein the barrier film comprises:

a substrate;

a first layer disposed on the substrate and comprising an oxidation product of polysilazane, wherein the polysilazane consists of a repeating unit represented by Chemical Formula 1, wherein each occurrence of the repeating unit represented by Chemical Formula 1 may be the same or different,

wherein R¹ and R² are each independently hydrogen, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an alkylsilyl group, an alkylamino group, an alkoxy group, or an aromatic hydrocarbon group; and

a second layer disposed directly on the first layer and comprising a thiol-ene polymer, the thiol-ene polymer comprising a polymerization product of a first monomer having at least two thiol groups, wherein at least one thiol group is present at one terminal end and at least one thiol group is present at another terminal end, and a second monomer represented by Chemical Formula 3,

wherein, in Chemical Formula 3,

X is an aliphatic organic group comprising a carbon-carbon double bond or a carbon-carbon triple bond, an aromatic organic group comprising a carbon-carbon double bond or a carbon-carbon triple bond, or an alicyclic organic group comprising a carbon-carbon double bond or a carbon-carbon triple bond,

R² is selected from hydrogen; a substituted or unsubstituted C1 to C30 linear or branched alkyl group; a substituted or unsubstituted C6 to C30 aryl group; a substituted or unsubstituted C3 to C30 heteroaryl group; a substituted or unsubstituted C3 to C30 cycloalkyl group; a substituted or unsubstituted C3 to C30 heterocycloalkyl group; a Cl to C10 alkoxy group; a hydroxy group; NH2; a substituted or unsubstituted C1 to C30 amine group (-NRR′, wherein R and R′ are independently hydrogen or a Cl to C30 linear or branched alkyl group); an isocyanate group; a halogen; -ROR′ (wherein R is a substituted or unsubstituted C1 to C20 alkylene group and R′ is hydrogen or a Cl to C20 linear or branched alkyl group); an acyl halide (-RC(═O)X, wherein R is a substituted or unsubstituted alkylene group and X is a halogen); —C(═O)OR′ (wherein R′ is hydrogen or a Cl to C20 linear or branched alkyl group); —CN; or —C(═O)ONRR′ (wherein R and R′ are independently hydrogen or a Cl to C20 linear or branched alkyl group),

L2 is a carbon atom, a substituted or unsubstituted C1 to C30 alkylene group, a substituted or unsubstituted C6 to C30 cycloalkylene group, a substituted or unsubstituted C6 to C30 arylene group, or a substituted or unsubstituted C3 to C30 heteroarylene group,

Y₂ is a single bond; a substituted or unsubstituted C1 to C30 alkylene group; a substituted or unsubstituted C2 to C30 alkenylene group; or a Cl to C30 alkylene group or a C2 to C30 alkenylene group wherein at least one methylene (-CH₂-) group is replaced by sulfonyl (-S(═O)₂-), carbonyl (-C(═O)-), ether (—O—), sulfide (—S—), sulfoxide (-S(═O)-), ester (-C(═O)O—), amide (-C(═O)NR-) (wherein R is hydrogen or a Cl to C10 linear or branched alkyl group), imine (—NR—) (wherein R is hydrogen or a Cl to C10 linear or branched alkyl group), or a combination thereof, n is an integer of 1 or more,

k3 is an integer of 0 or more,

k4 is an integer of 1 or more, and

the sum of n and k4 is an integer of 3 or more,

provided that when Y₂ is not a single bond, n does not exceed the valence of Y₂, and

provided that the sum of k3 and k4 does not exceed the valence of L₂ and

wherein a surface of the second layer contacts at least a portion of the surface of the quantum dot-polymer composite.