Molecular Design toward High Hole Mobility Organic Semiconductors: Tetraceno[2,3-c]thiophene Derivatives of Ultrasmall Reorganization Energies

Abstract

The internal reorganization energies (λ+) associated with the transfer of a hole in a series of p-type five-ring heteroarenes were investigated using density functional theory (DFT). The λ+ value of the first model compound, tetraceno[2,3-c]thiophene (TcTH), is 31 meV less than that of its analogue, the well-known tetraceno[2,3-b]thiophene (TbTH), because of the fusing of thiophene in a nonbonding fashion. The λ+ value of cyanated TcTH (DCN-TcTH) is as low as 50 meV. For a given degree of electronic coupling (t), the electron exchange rate (ket) of DCN-TcTH is 2.2 times that of TbTH. This study strongly indicates that TcTH and its derivatives are promising materials for fabricating high-mobility p-type organic field effect transistors.