Transparent conductors (TCs) play a vital role in displays, solar cells, and emerging printed electronics. Here, we report a solution-processable n-doped organic conductor from copper-catalyzed cascade reactions in the air, which involves oxidative polymerization and reductive doping in one pot. The formed polymer ink is shelf-stable over 20 days and can endure storage temperatures from -20 to 65 °C. The optimized n-doped thin-film TC exhibits a low sheet resistance of 45 Ω/sq and a high transmittance (T550 > 80%), which can rival indium tin oxide. The transparent organic conductor exhibits excellent durability under accelerated weathering tests (85 °C/85% RH). Furthermore, the n-doped polymer film can also function as an electrode material with a high volumetric capacity. When it is paired with p-doped PEDOT:PSS, a record-high coloration efficiency is obtained in a dual-polymer electrochromic device.