We demonstrate n-type doping of pentacene with the powerful reducing molecule decamethylcobaltocene (CoCp 2 * ). Characterization of pentacene films deposited in a background pressure of CoCp 2 * by X-ray photoemission spectroscopy and Rutherford backscattering confirm that the concentration of incorporated donor molecules can be controlled to a level as high as 1%. Ultraviolet photoemission spectroscopy show Fermi level (E F ) shifts toward unoccupied pentacene states, indicative of an increase in the electron concentration. A 1% donor incorporation level brings E F to 0.6 eV below the pentacene lowest unoccupied molecular orbital. The corresponding electron density of ∼ 10 18 cm -3 is confirmed by capacitance-voltage measurements on a metal-pentacene-oxide-silicon structure. The demonstration of n-doping suggests applications of CoCp 2 * to pentacene contacts or channel regions of pentacene OTFTs.
|Original language||English (US)|
|Number of pages||7|
|Journal||Applied Physics A: Materials Science and Processing|
|State||Published - Apr 1 2009|
All Science Journal Classification (ASJC) codes
- Materials Science(all)