The Electrochemistry of Poly(3‐octylthiophene) Based Light‐Emitting Electrochemical Cells

Cyclic voltammetry (CV) has been performed on light‐emitting electrochemical cells (LECs) using poly(3‐octylthiophene) (P3OT) as the active luminescent polymer. Above the threshold voltage, current in an LEC consists of ionic and electronic components. A purely ionic (negative) component is clearly discernible in the return scan of the CV below threshold when, as a result of the relaxation of the p‐n junction, the electronic current becomes negligible. Analysis of the peak negative current reveals that LECs exhibit a mixture of thin film and diffusion controlled current behavior. Weak orange light emission is observed with an onset above 2 V.