Monolayers Improve Organic Semiconductors

Rutgers University physicists report that self-assembled organosilane monolayer films can increase the electrical conductivity of organic semiconductors by several orders of magnitude (Nat. Mater., DOI: 10.1038/nmat2059). The investigation may lead to new, simpler ways of converting organic materials—which are attractive due to their low cost but tend to be poor electrical conductors—into useful electronic components for displays, chemical sensors, and other applications. By coating crystals of the organic semiconductors rubrene and tetracene with thin films of heavily fluorinated silane compounds, Matthew F. Calhoun, Michael E. Gershenson, Vitaly Podzorov, and coworkers boost the crystals' conductivity by four to five orders of magnitude compared with uncoated crystals. Nonfluorinated compounds, such as n-octyltrichlorosilane, also increase conductivity, but the fluorinated monolayers give a more pronounced effect. The researchers also note that the presence of xylene, chlorobenzene, and other compounds leads to rapid and reversible changes in the coated crystals' conductivity, which suggests potential chemical-sensing applications.