Recent annealing experiments have shown that films are highly susceptible to various atmospheres, going to their destruction in particular environments well below 200°C. Moreover, before this abrupt transition a sizable increase in photoluminescence has been observed especially by annealing in humid air. This property, which hints at a new phase of the material with some analogies to the recently discovered δ-phase except for a much lower temperature, displays a remarkable stability in ambient air, a result with important implications both for the development of environmentally stable organic light-emitting diodes devices and for basic understanding of the morphological structure of systems. © 2004 The Electrochemical Society. All rights reserved.