Bathocuproine (BCP) is well known as a hole-blocking material and is often used in organic light-emitting diodes and organic solar cells. However. BCP film is immediately polycrystallized after vapor deposition. We achieved stabilization of vacuum-deposited BCP-based thin film using the organic alloy method. Organic alloy method led not only to the suppression of crystallization but also to improvement of electroluminescence properties of devices using a hole-blocking layer. (c) 2007 Elsevier B.V. All rights reserved.