UC Santa Barbara

Ionic-organic ratchets have the ability to rectify alternating electric fields into DC current to sustain low power electronics, such as RFID devices. Until now however, organic electronic ratchets have only been realized using p-type organic semiconductors. The development and performance of organic n-type devices have historically lagged far behind their p-type equivalents, largely due to the high susceptibility of n-type organic semiconductors to electron trapping. A previously developed charge pump model predicts an output current for ionic-organic ratchets that is linearly dependent on frequency, and agrees well with data from p-type devices. In this model, the capacitance of the device is assumed to be constant over the measured frequency range. N-type ratchets based on PCBM and N2200 exhibit output currents that deviate from a linear relationship with frequency. Impedance spectroscopy measurements suggest that this deviation is caused by the presence of ions and traps which modify the frequency dependence of the device capacitance. This work demonstrates the first n-type organic electronic ratchet, capable of producing an output power comparable to its p-type counterparts.