Highly efficient phosphorescent organic light-emitting diodes with an orange-emitting crosslinkable iridium(III) complex have been presented. The crosslinkable iridium-containing triplet-emitting dopant and organic layers were spin-coated from solution and crosslinked insoluble films were formed by using cationic ring-opening polymerization (CROP). An additional electron-transporting layer (ETL) on top of the emissive layer (EML) were also introduced that reduced luminescence quenching at the cathode and improved the charge balance, leading to a significantly improved device performance. Maximum efficiency of the phosphorescent device was improved by a factor of 30, compared to a device without an ETL.