Influence of ionic size to the pulse responses of semiconducting polymer/electrolyte hetero-junctions

Pt/Poly[2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV)/polyethylene oxide (PEO) + Alkali ions/Ag devices were fabricated. Microstructure analysis indicated that Cs and K ions were doped initially into the semiconducting polymer after fabrication, which suggests resemblance to the resting state of bio-synapse. The pulse responses of Cs-doped device potentiated monotonically with increased frequency. K-doped device had a threshold frequency at about 60 Hz, and it responded in potentiation at frequency higher than this threshold. The special filtering effects should relate to the ionic states in nanoscale in both semiconducting polymer and electrolyte. Thus, these two types of device could be used in signal computing.