Chromofore Poling in Thin Films of Organic Glasses. 1. Overview of Corona Discharge Application

The introductory article in a series of works on the chromofore poling in thin films of organic glasses presents an overview of corona discharge applications, with a brief excursion into physics of the phenomenon. The authors consider this technique as related to the nonlinear optical (NLO) polymers. Its key points are as follows.

In the ambient air such discharge is strongly affected by variable humidity and, consequently, uncertain concentration of the predominant charge carrier ((H₂O)_nH⁺). To realize a repeatable poling process the composition of discharge atmosphere should be controlled (e.g. for pure nitrogen gas). In the case of discharge in N2 the highly reactive ozone production could be avoided. To obtain second-order nonlinear activity of polymeric materials, a simple point/plane (two-electrode) technique of corona charging is successfully applied, which however does not provide information about the sample surface charge buildup and the efficiency of poling process. To study the dynamics of both the poling and the charge transport processes a three-electrode charging system - the corona triode - should be used.