Rectifying behavior of charge transfer complexes of tetrakis(dimethylamino)ethene with acceptor molecules: a theoretical study.

The effect of electric field induced electron transfer on the rectification properties of molecular rectifiers based on charge transfer complexes of tetrakis(dimethylamino)ethane (TDAE) with acceptor molecules was explored. The current-voltage curves and the rectification ratios (RR) for two different molecular rectifiers were obtained using a direct ab initio method at M06/LACVP(d) level of theory in the range from -2 to +2 V. The highest RR of 25.7 was determined for the complex of TDAE with 2-nitropyrene-4,5,9,10-tetraone at 0.5 V (D1), while another rectifier [complex of TDAE with 2,7-dimethyl nitropyrene-4,5,9,10-tetraone (D2)] showed a maximum RR of only 2.9 at 0.3 V. The electric field induced electron transfer occurring in D1 creates a one-way conducting channel consisting of two SOMOs involving the entire D1 complex. In the case of D2, no electron transfer occurs at the applied bias voltages due to the relatively high energy difference between HOMO and LUMO.