Thermoelectric Gating Organic Electrochemical Transistors Enabled by Printable Ionogels With n‐p Convertible Thermopower

Organic electrochemical transistors (OECTs) are promising for bioelectronics and low‐power logic owing to their mixed ionic‐electronic conduction and mechanical softness. However, thermoelectric gating of OECTs remains unexplored due to the incompatibility of rigid, electronically dominated thermoelectric modules with hydrated soft systems. Here, we introduce printable thermoelectric ionogels with n‐p convertible thermopower, where the Seebeck coefficient is tunable from –3.61 to +9.74 mV K − 1 through facile [EMIm][Cl] doping. These ionogels act simultaneously as thermoelectric legs and ionic dielectrics, enabling direct integration with OECTs to realize soft, complementary p–n thermoelectric modules. We demonstrate thermoelectric gating of both BBL‐ and p(g2T‐T)‐based OECTs, achieving high on/off ratios (>10 3 ) and robust transconductance under low temperature gradients (<30 K), while retaining mechanical stretchability. This strategy provides a general framework for coupling thermoelectric functionality with OECTs, opening new avenues for energy‐autonomous, flexible electronics with built‐in thermal sensing and adaptive control.