| It is well known that the aluminium cathode performs dramatically better when a thin lithium fluoride(LiF) layer inserted in the orgaic electronic devices. However, the underlying machanism discussion is quite complicated, and not fully understood so far although the LiF interlayer is used widely in the field of organic electronics. Perhaps, it is the most difficult situation that no effective tranditional chemical means is found suitable for the cases around the buried solid film. Now, the quantum and computational chemistry is being well-developed, and could be an helpful alternative method for the interlayer effects.In this thesis, we perform theoretical calculations to get insights into the microscopic interacted systems possibly present at the interlayers. Based on such computational researches, we attempt to present some possible understandings from chemical microscopic views, and accordingly to benefit the further researches from other researchers all over the world. The major research contents are outlined as follows:(1) The reactions between one single aluminum atom and(LiF)n(n = 2, 4, 16) clusters were investigated. All types of stationary points(including transition states, local minima) in the potential energy surfaces were optimized and verified via frequency calculations. The reaction paths were found and discussed based on evaluations of energy parameters. The findings include(i) the barriers of each reaction step are within acceptable heights of no more than 15.0 kcal/mol;(ii) the last step for atom Li coming off from the cluster is about 10.0 kcal/mol endothermic, while the department of AlF molecules, which will encounter each other for the formation of AlF3, from the cluster is about 20.0 kcal/mol endothermic;(iii) the formation of AlF3 and the release of Li atom are in two different chemical reaction routes;(iv) even if no dissociation occurs, the Al-(LiF)n systems have chances to change to some structures, which behaves like electrides with loosely bound electrons, which can facilitate the electron transfers at interface and may shift locally the Fermi level.(2) The alkali metal(AM) fluoride clusters(AMn+1Fn) with one excess of AM atom and their Al substitutes [Al(AMF)n] were investigated by geometrical optimizations, analyses on the highest singly occupied molecular orbitals(SOMO) and the calculations on the vertical ionization energies(VIE). The results indicate that(i) Al atom interact well with the uncompleted rock salt clusters(AMF)n;(ii) All the Al substitutes of the classic prototypes of AMn+1Fn clusters were found with low VIEs, which would significantly benefit the electron injection processes from the electrode to the organic layers;(iii) if no subsequent reaction occurs, in these Al(AMF)n clusters, the chemical valence of Al should be +1, which needs the attentions from experimental researchers.(3) The systems of mer-AlQ3 binding AM ions were theoretically investigated and discussed. The energy profiles on AM ions interaction with mer-AlQ3 and the lowest unoccupied molecular orbitals(LUMOs) of [M-AlQ3]+(M=Na, Rb) were shown. To conclude for this part:(i) the two types of structures for the complexes [M-AlQ3]+(M=Li, Na, K, Rb, Cs) occupies close in energy, and transformation between the two is not easy because of the relatively large barrier(about 5~14 kcal/mol);(ii) The energy profiles of M-AlQ3 are closely flat, and the adopted structures of M-Al Q3 are relatively random on electron injection into [M-AlQ3]+;(iii) the localizations of LUMO in [M-AlQ3]+ can be tuned depending on the different binding sites, which will richen the channel choices of electron transport and facilitate the electron injection at interfaces. |
PDF Full Text Request