Complex Organic Semiconductor Devices Utilizing Threshold Voltage Shifting and Carrier Sign Reversal

We consider a range of materials and mechanisms that lead to nonvolatile switching in field-effect transistors made from organic semiconductors (OFETs). Charging of gate dielectrics, secondary dielectrics, and/or the semiconductor/dielectric interface can greatly shift the threshold voltage in these OFETs. The dielectrics can consist of nonpolar electrets or ferroelectric polymers. In the particular case of SiO$_{2}$ electret coated with a hydrophobic surface layer, the shift is permanent on the timescale of years and is in quantitative agreement with measured surface charge. The semiconductor perfluoro copper phthalocyanine is shifted from electron- to hole-carrying by application of sufficient field from a corona apparatus. Inverter circuits were built from pairs of OFETs based on a single semiconductor, differing only in the quantity of stored gate charge.