A soluble and air-stable organic semiconductor with high electron mobility

Electronic devices based on organic semiconductors offer an attractive alte rnative to conventional inorganic devices due to potentially lower costs, s impler packaging and compatibility with flexible substrates(1,2). As is the case for silicon-based microelectronics, the use of complementary logic el ements-requiring n- and p-type semiconductors whose majority charge carrier s are electrons and holes, respectively-is expected to be crucial to achiev ing low-power, high-speed performance. Similarly, the electron-segregating domains of photovoltaic assemblies require both n- and p-type semiconductor s(3-5). Stable organic p-type semiconductors are known(6), but practically useful n-type semiconductor materials have proved difficult to develop, ref lecting the unfavourable electrochemical properties of known, electron-dema nding polymers(7). Although high electron mobilities have been obtained for organic materials, these values are usually obtained for single crystals a t low temperatures, whereas practically useful field-effect transistors (FE Ts) will have to be made of polycrystalline films that remain functional at room temperature. A few organic n-type semiconductors that can be used in FETs are known, but these suffer from low electron mobility, poor stability in air and/or demanding processing conditions(8-10). Here we report a crys tallographically engineered naphthalenetetracarboxylic diimide derivative t hat allows us to fabricate solution-cast n-channel FETs with promising perf ormance at ambient conditions. By integrating our n-channel FETs with solut ion-deposited p-channel FETs, we are able to produce a complementary invert er circuit whose active layers are deposited entirely from the liquid phase . We expect that other complementary circuit designs(11) can be realized by this approach as well.