Time-resolved kelvin probe force microscopy to study population and depopulation of traps in electron or hole majority organic semiconductors

Abstract

We present a time-resolved Kelvin Probe Force Microscopy (KPFM) technique that can record carrier motion on the scale of milliseconds, appropriate for polycrystalline materials like organic semiconductors. The organic semiconductors are studied in a transistor geometry to which we apply a step voltage to the back-gate. We record the change in potential at a specific location and observe the times associated with filling and emptying majority carrier traps, observed in hole majority carrier poly(3-hexylthiophene-2,5-diyl) (P3HT) and a perylene diimide electron majority carrier, PDI-CN2. We see signs of bias stress with repeated measurements in P3HT.