Cover Picture: Microscopic Evidence for Spatially Inhomogeneous Charge Trapping in Pentacene (Adv. Mater. 11/2005)



Trapped charge has been observed in polycrystalline pentacene films by electric force microscopy in work reported by Muller and Marohn on p. 1410. The cover shows an optical fiber watching the motion of a metal-coated cantilever hovering over a polycrystalline pentacene film. The film occupies the 6.5  μm gap in a working field-effect transistor. Trapped charge (dark blue and black areas in the pentacene) appears as large patches randomly distributed throughout the device, implying that long-lived traps in polycrystalline pentacene are not correlated with grain boundaries.