The charge transfer anion-radical alkali-metal salts M +TCNQ − (M = Li, Na, K): The structures and static hyperpolarizabilities

Abstract

The structures and nonlinear optical (NLO) properties of the charge transfer anion-radical salts without excess electron, M +TCNQ − (M = Li, Na, K) are studied for the first time. These anion-radical salts exhibit large first ( β 0) and second ( γ 0) hyperpolarizabilities, which are related to the ligand-to-metal charge transfer (LMCT) transitions. The largest β 0 and γ 0 values for K +TCNQ − are 2.8 × 10 4 and 2.0 × 10 6 a.u., respectively. In addition, the effect of alkali-metal doping and monotonous dependence on the alkali atomic number of both β 0 and γ 0 are observed. These results may be beneficial to design high-performance NLO materials.