The photoluminescence properties of the blend films consisting of the hole transport and electron transport materials, PVK and Alq3, are studied by steady-state and time-resolved photoluminescence (PL) spectroscopy. Both the relative intensity and the photoluminescence lifetime are intensively dependent of the weight ratios of PVK and Alq3. The detailed analysis of experiment data provides clear evidence for a Forster energy transfer from excited PVK, as donor, to Alq3, as acceptor, based on nonradiative resonant transfer mechanism, and allows the determination of Forster radius and the concentration dependent energy transfer efficiency. (C) 2008 Elsevier B. V. All rights reserved.