C60andC70fullerenes and potassium fullerides

Absorption spectra and electronic properties of alkali-metal-doped C60

“…2 and 3. This suggests high potassium diffusion rates through thin films of AxC60 which is in agreement with recent observations [9,14,15].…”

“…This requires that the sticking coefficient of the alkali metal remains unchanged and that the potassium diffusion rate through the sample is much greater than the deposition rate. While the latter requirement appears to be met, the most recent studies indicate certain nonlinearities in the sticking coefficient of potassium on C60 films [9]. Therefore, direct correlation between the observed spectra and KxC60 stoichiometry using the deposition time is strictly correct only for x=0 and x=6 while intermediate concentrations should be regarded as approximate.…”

Fullerenes

“…41 It has also been reported that it is possible to place a potassium atom endohedrally inside the C 6 o ball while at the same time substituting a boron for a carbon atom on the surface of the ball. 30 Among the alkali metals, Li, Na, K, Rb, and Cs 42 have all been used as exohedral dopants for C 6 o, as well as intermetallic mixtures of these alkali metals such as Na 2 K 43 - 44 and Rb^Cs r 45 The doping of the C 60 with alkali metals can be achieved in a two-temperature oven, similar to the apparatus used to prepare alkali-metal graphite intercalation compounds. 46 This approach works well with powdered samples, and the stoichiometry is controlled by the number of moles of alkali-metal introduced into the sealed ampoule (quartz or Pyrex) relative to the number of moles of C 60 , the temperatures of the reagents, and the duration of the reactions.…”

“…30 for C 60 and K^C 60 (0 *£ x =£ 6), 44 where the intensity maxima correspond to peaks in the density of states on the basis of a one-electron picture and a constant matrix element approximation, after corrections are made for the screening or correlation energy (~2 eV) of the Hubbard model. In the photoemission experiments, the density of states for the occupied levels is probed, while in the inverse photoemission experiments the density of unoccupied states is probed.…”

Source/drain electrodes contact effect on the stability of bottom-contact pentacene field-effect transistors

“…[1][2][3][4][5] In the last few decades, many promising organic materials with high charge mobilities have been developed. [6][7][8] Unfortunately, in spite of the high bulk mobility of many organic materials, the corresponding OFETs often exhibited relatively low performance when utilizing these organic materials to fabricate bottomcontact (BC) devices. 9 However, the commercialization of OFETs is still highly desirable for the BC configuration, as they not only significantly improve the sensitivity of OFET-based sensors, but they also dramatically reduce device cost.…”