Organic multi-valued logic (MVL) circuits can substantially improve the data processing efficiency in highly advanced wearable electronics. Organic ternary logic circuits can be implemented by utilizing the negative transconductance (NTC) of heterojunction transistors (HJTs). To achieve high-performance organic ternary logic circuits, the range of NTC in HJTs must be optimized in advance to ensure the well-defined intermediate logic state in ternary logic inverters (T-inverters). Herein, simple and efficient strategy, which enables the systematic control of the range and position of NTC in H-TRs is presented. Based on the semiconductor thickness variation and asymmetric S/D electrodes, the T-inverter exhibits full-swing operation with three distinguishable logic states, resulting in high static noise margin. Moreover, a flexible T-inverter with an ultrathin polymer dielectric is demonstrated, whose operating voltage was less than 8 V.