Blue organic light-emitting diodes with non-doped emissive layer (EML) structures have been garnered increasing interest due to their convenience of manufacturing process. For this purpose, we designed and synthesized two novel anthracene derivatives, PO2PhAnTz and PO2PhAnBI. Both derivatives exhibited bright blue electroluminescence emission and a relatively low operating voltage with a simple bilayer device structure. The PO2PhAnBI with triphenyl-phosphine oxide moiety as host, anthracene core as dopant and benzimidazole as electron transport group, realized a balanced bipolar transport and attained a maximum external quantum efficiency of 5.74 %. The findings shed light on the molecule design role toward high-efficiency non-doped blue OLEDs.
Four new Bi(III) phosphates, K 6 Bi 13 (PO 4 ) 15 , K 5 Bi(P 2 O 7 ) 2 , and A 5 Bi 5 (PO 4 ) 4 (P 2 O 7 ) 2 (A= K, Rb) with the different condensed P-O groups have been successfully synthesized via the solid-state reactions. The single crystals X-ray diffractions show that they crystallize in the different space groups (K 6 Bi 13 (PO 4 ) 15 : C 2; K 5 Bi(P 2 O 7 ) 2 : P 1 ¯ ; K 5 Bi 5 (PO 4 ) 4 (P 2 O 7 ) 2 and Rb 5 Bi 5 (PO 4 ) 4 (P 2 O 7 ) 2 : P 2 1 / c ). The structure of K 6 Bi 13 (PO 4 ) 15 can be described as a three-dimensional (3D) network composed of the Bi-O polyhedra and PO 4 tetrahedra with K atoms filling in the space to balance the residual charges. K 5 Bi(P 2 O 7 ) 2 features 2D [BiP 4 O 14 ] ∞ layers built by the BiO 6 octahedra and P 2 O 7 dimers and the adjacent [BiP 4 O 14 ] ∞ layers are bridged by the K atoms. A 5 Bi 5 (PO 4 ) 4 (P 2 O 7 ) 2 (A = K, Rb) contain two different condensed P-O groups, PO 4 tetrahedra and P 2 O 7 dimers, which are connected by Bi-O polyhedra to construct the complicated 3D framework with K/Rb atoms located in the tunnels. Note that, the compounds that simultaneously contain two different types of P-O groups are still rare in phosphates. Detailed structural comparisons of Bi 3+ -containing phosphates indicate that the Bi/P ratios have a significant effect on the condensed degrees of PO 4 groups. Furthermore, TG-DSC, IR, UV-Vis-NIR diffuse reflectance spectra and SHG test for title compounds have also been reported.