Three-dimensionally stacked flexible integrated circuit: Amorphous oxide/polymer hybrid complementary inverter using n-type a-In–Ga–Zn–O and p-type poly-(9,9-dioctylfluorene-co-bithiophene) thin-film transistors

A three-dimensional vertically-stacked flexible integrated circuit is demonstrated based on hybrid complementary inverters made of n-type In–Ga–Zn–O (a-IGZO) amorphous oxide thin-film transistors (TFTs) and p-type poly-(9,9-dioctylfluorene-co-bithiophene) (F8T2) polymer TFTs, where all the fabrication processes were performed at temperatures ≤120 °C. Saturation mobilities of the a-IGZO TFT and the F8T2 TFT are ∼3.2 and ∼1.7×10−3 cm2 V−1 s−1, respectively, from which we chose the appropriate dimensions of the TFTs so as to obtain a good balance for the inverter operation. The maximum voltage gain is ∼67, which is better than those reported for organic/oxide hybrid complementary inverters.