Flexible Organic Field-Effect Transistor (OFET) Based 2T0C DRAM Cells with 2-Bit Operation and Extended Retention

The emerging demand of data storage in wearable devices, flexible circuits based on organic semiconductor materials are encouraged, while organic field effect transistors face the challenges of low operating voltage and high on/off ratio. In this work, a high-performance flexible organic field effect transistor (OFET) is built with a threshold voltage range of -0.45 to -0.86 V and an on/off ratio between 10⁶ and 10⁸. The subthreshold swing of the OFETs is lower than 60 mV dec^-1. Through finite element analysis, the OFET shows excellent mechanical stability owing to the stress relief during the bending process. Furthermore, a flexible 2T0C DRAM cell is demonstrated based on the OFETs. The stable electrical characteristics of the OFETs enable the 2T0C DRAM cell to achieve a retention time exceeding 300 s under both initial and bending conditions. Additionally, 2-bit memory operations are realized by adjusting the voltage of the word bit line (V_WBL) and the voltage of the word write line (V_WWL), demonstrating consistent performance in both the initial and after-bending state.