Low energy emission bands in a small molecular fluorene derivative for organic light-emitting diodes S. L. Lou, H.S. Yu, W. M. Ma, Y. Jiang and Q. Zhang Eur. Phys. J. D, 50 1 (2008) 21-26 Published online: 15 October 2008 DOI: 10.1140/epjd/e2008-00190-3