Flexible organic field-effect transistor nonvolatile memory enabling bipolar charge storage by small-molecule floating gate

A nonvolatile memory based on the floating-gate organic field-effect transistor was prepared by using the vacuum thermal evaporation taking small-molecule fullerenes (C60) as the floating-gate layer and long-chain alkane molecule tetratetracontane as the tunneling layer. Intrinsic correlations between microstructures of the floating gate and the memory performance, the physical mechanisms of the carrier injection, transfer, and storage, and the relationships between the charge-trapping capability of the floating-gate layers of different thicknesses made of small-molecule C60 and key parameters of the memory were investigated. The results show that the memory covers the charges stored in the manner of the opposite polarity during operation under the programming and erasing voltages. The bipolar charges (electrons and holes) are injected and captured in the floating gate. After optimization, the high-performance memory has an average memory window of 6.5 V, remains stable for more than one year, and is reliable for more than 220 programming/erasing cycles. Moreover, the memory also has excellent endurance to mechanical bending and retains favorable storage stability after being compressed or tensed 500 times to a bend-radius of 5 mm.