Two new lanthanide complexes [Ln-(hfaa)(3)(Py-Im)] [hfaa = hexafluoroacetylacetone, Py-Im = 2-(2-pyridyl)benzimidazole and Ln = Eu(III) (1) and Tb(III) (2)] were synthesized and characterized. An X-ray crystal structure determination confirms that complex 1 is eight-coordinate with a distorted trigonal dodecahedral geometry. It shows typical vivid red Eu(III) emission in the solid state, in solution, and in a polymer matrix. The observed lifetime (tau(obs)) of complex 1 in the solid state, in dichloromethane (DCM) solution, and in thin films is 833.01, 837.95, and 626.16-715.69 mu s, respectively, with a photoluminescence quantum yield Q(Eu)(L) approximate to 33% in DCM solution. Complex 2 displays a yellowish- green emission in the solid state (tau(obs) approximate to 36.99 mu s), while a near white-light emission in solution (x; 0.2574: y; 0.3371) and in thin films. Therefore, it is a potential candidate for generating single-component white light-emitting materials for solid-state lighting applications. The kinetic scheme for modeling energy-transfer processes shows that the main donor state for 1 is the ligand triplet state (T-1) and that energy transfer occurs to both the D-5(1) (56.55%) and D-5(0) (40.58%) levels. We fabricated a series of single- and double-layer organic light-emitting devices using complex 1. The luminance of the optimized double-layer electroluminescence (EL) device was 373 cd/m(2) with very low turn-on voltage of similar to 4.2 V. Complex 1 was further utilized as a sensitizer to improve the EL of a red-emitting iridium complex PQ(2)Ir(dpm) (PQ = phenylquinoly-N,C2', dpm = dipivaloylmethane). The codoped device achieved a maximum brightness and maximum current efficiency (eta(c)) of 93 224 cd/m(2) and 36.38 cd/A, respectively.