Transformation of polarons to bipolarons in disordered matter

The polaron to bipolaron transition in disordered media under the influence of a broadband ac electric field is suggested: ac conductivity versus frequency measurements in disordered media with inhomogeneous disorder induce spatiotemporal fluctuations of the density of polarons yielding polaron to bipolaron transformation. The external field results in the transition, alternatively to an increasing doping level. The assertion is confirmed by performing successive complex impedance measurements in disordered media. A systematic increase in the real part of the ac conductivity in the frequency domain, followed by mutual reduction in the magnetic inductivity of conducting polypyrrole, are explained.