Electrochemical modulation enhancing the saturation absorption of polyaniline

Materials with electrically tunable optical properties offer opportunities for novel photon applications. Here it is reported that the electrochemical treatment can control the third-order nonlinear absorption of polyaniline. Under the excitation of 800 nm laser, the film shows strong saturation absorption (SA), and the nonlinear absorption coefficient ranges from −1024.27 to −316.29 cm GW-1 depending on the external voltage. The SA can be attributed to Pauli blocking associated with polaron levels in the band gap, and electrochemical doping can change the feature of polaron levels and, accordingly the nonlinear optical property of the material.