We fabricated two organic diodes, one of which consists of a double layer structure of TPD/Tb(ACA)(3)phen and in the other one a mixture layer is inserted between the double layer, i.e., TPD/TPD:Tb(ACA)(3)phen (1:1, 30 nm)/Tb(ACA)(3)phen, here TPD and Tb(ACA)(3)phen are (N,N'-diphenyl-N,N'-bis(3-methyl-phenyl)-1,1'-biphenyl-4,4'-diamine) and tris(acetylacetonato)-(mono-phenothroline) terbium, respectively. Both the devices show electroluminescence (EL) properties under forward bias and photovoltaic (PV) effects under illumination of ultraviolet (UV) light. For the device with a mixture layer, the EL performance and PV effects were both significantly improved. A maximum EL brightness of 150 cd/m(2) under bias of 17 V and a maximum efficiency of 1.1 cd/A at 7.5 V were obtained. Moreover, the diode shows a short-circuit current (I-sc) of 43 mu A cm(-2), an open-circuit voltage (V-oc) of 1.1 V, a fill factor (FF) of 0.32, and an overall power conversion efficiency (eta(PV)) of 1.0%, under illumination of 365 rim UV light with 1.5 mW/cm(2). The improvements of PV- and EL-properties were presumably attributed to the increased intermolecular contacts in the mixture of TPD and Tb-complex. In addition, a shift of EL color from UV-blue to green-yellow was also observed when a Mixture layer of TPD with Tb-complex was inserted. The operation mechanisms of the EL- and the PV-processes of the diodes with different structures were further discussed. (C) 2007 Elsevier Ltd. All rights reserved.