Semiconductor properties of perylene diimide derivatives

Density functional theory (DFT) calculations were carried out to study the charge transfer properties of N,N′-bisperylene-3,4,9,10-tetracarboxylic diimide (1), N,N′-bis(3-chlorobenzyl)perylene-3,4,9,10-tetracarboxylic diimide (2), N,N′-bis(3-fluorobenzyl)perylene-3,4,9,10-tetracarboxylic diimide (3), and N,N′-bis(3,3-difluorobenzyl)perylene- 3,4,9,10-tetracarboxylic diimide (4) for use as organic field effect transistors (OFETs). The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies, ionization energy (IE), electron affinity (EA), and reorganization energy (λ) were investigated for these compounds. Corresponding to energy changes in the HOMO and LUMO for 2-4, the introduction of chlorobenzyl or fluorobenzyl groups leads to high adiabatic electron affinity (EA_a) values for 2-4. The transfer integral (V) and field effect transistor (FET) properties for the four compounds with known crystal structures were calculated based on Marcus electron transfer theory. The calculated results reveal that a very small injection barrier exists relative to the Au source-drain electrode of 1-4 for electrons, producing good potential n-type semiconductors. Intrinsic electron transfer mobilities (μ_-) of 5.39, 0.59, 0.023, and 0.17 cm²· V^-1· s^-1 were calculated for compounds 1-4, respectively. The high intrinsic electron mobilities for 1-4 were rationalized by examining the changes in geometric structure upon reduction and charge transfer integral for the different transfer modes in crystal 3.