Length-dependent Conductance of conjugated molecular junctions

Molecular junction is a promising candidate for devices nowadays, especially the conjugated molecule with much higher conductance compared to sigma bond alkanes. The decay constant β, which describes the length-dependent conductance, is one of the most important parameters in molecular junctions. To investigate the decay constant, we introduce the exponential dependence first, and then explain by theory. After the comparison of β values of conjugated systems and sigma bond compounds, we mainly focus various aspects that can affect the decay constant. The transition from tunneling to hopping is discussed in details, with several series of samples. Other aspects, such as anchor groups, twisted angles and conjugated limitations are also included. Key word: conjugated, molecular length, decay constant, anchor group, tunneling, hopping, twisted angle.