An electronic or optoelectronic device, disposed on a substrate and encapsulated with a lid in which the lid and substrate are bonded together with a sealant/adhesive disposed on the whole area between the substrate and the lid, the sealant/adhesive comprising a radiation-curable adhesive/sealant composition comprising: a) a radiation-curable barrier rubber resin not containing siloxane functionality, b) a radiation-curable resin diluent c) a photoinitiating system comprising one or more photoinitiators selected from diaryliodonium salts and triarylsulfonium salts and optionally one or more photosensitizers selected from isopropylthioxanthone and chloropropoxythioxanthone (CPTX), wherein the radiation-curable barrier rubber resin is an olefin-terminal polyisobutylene, polyisobutylene acrylate, polyisobutylene epoxy, polyisobutylene vinyl ether, butyl rubber, epoxidized butyl rubber, acrylated butyl rubber, maleated butyl rubber or mercaptan functional butyl rubber, and wherein in a radiation curable resin diluent is bisphenol F diglycidyl ether, bisphenol A diglycidyl ether, tetramethylbiphenyldiglycidyl ether, resorcinol diglycidyl ether, hydrogenated bisphenol A diglycidylether, cyclohexanedimethylol diglycidyl ether, cycloaliphatic epoxy resin, oxetane resin, cyclohexanedimethylol divinyl ether, dodecyl vinyl ether, hexane diol diacrylate, trimethylolpropane triacrylate, cyclohexanedimethylol diacrylate, dicyclo-pentadienedimethylol diacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, poly(butadiene)dimethacrylate, bisphenol A based acrylated epoxy, maleimide resins having the structures in which (C 36) represents a hydrocarbon moiety having 36 carbons, which can be a straight or branched chain, with or without cyclic structures; and pentaerythritoltetrakis(3-mercaptopropionate)/triallyl-isocyanurate, diallylchlorendate or tetraallylbisphenol A. a) a radiation-curable barrier rubber resin not containing siloxane functionality, b) a radiation-curable resin diluent c) a photoinitiating system comprising one or more photoinitiators selected from diaryliodonium salts and triarylsulfonium salts and optionally one or more photosensitizers selected from isopropylthioxanthone and chloropropoxythioxanthone (CPTX), wherein the radiation-curable barrier rubber resin is an olefin-terminal polyisobutylene, polyisobutylene acrylate, polyisobutylene epoxy, polyisobutylene vinyl ether, butyl rubber, epoxidized butyl rubber, acrylated butyl rubber, maleated butyl rubber or mercaptan functional butyl rubber, and wherein in a radiation curable resin diluent is bisphenol F diglycidyl ether, bisphenol A diglycidyl ether, tetramethylbiphenyldiglycidyl ether, resorcinol diglycidyl ether, hydrogenated bisphenol A diglycidylether, cyclohexanedimethylol diglycidyl ether, cycloaliphatic epoxy resin, oxetane resin, cyclohexanedimethylol divinyl ether, dodecyl vinyl ether, hexane diol diacrylate, trimethylolpropane triacrylate, cyclohexanedimethylol diacrylate, dicyclo-pentadienedimethylol diacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, poly(butadiene)dimethacrylate, bisphenol A based acrylated epoxy, maleimide resins having the structures in which (C 36) represents a hydrocarbon moiety having 36 carbons, which can be a straight or branched chain, with or without cyclic structures; and pentaerythritoltetrakis(3-mercaptopropionate)/triallyl-isocyanurate, diallylchlorendate or tetraallylbisphenol A.