Hole transporting material 5,10,15-tribenzyl-5Hdiindolo[3,2-a:3',2'-c]-carbazole for efficient optoelectronic applications as an active layer

In order to explore the novel application of the transparent hole-transporting material 5,10,15-tribenzyl-5Hdiindolo[3,2-a：3＇,2＇-c]-carbazole（TBDI）,in this article TBDI is used as an active layer but not a buffer layer in a photodetector（PD）,organic light-emitting diode（OLED）,and organic photovoltaic cell（OPV） for the first time.Firstly,the absorption and emission spectra of a blend layer comprised of TBDI and electron-transporting material bis-（2-methyl-8-quinolinate） 4-phenylphenolate（BAlq） are investigated.Based on the absorption properties,an organic PD with a peak absorption at 320 nm is fabricated,and a relatively-high detectivity of 2.44×10^（11） cm· Hz^（1/2）/W under 320-nm illumination is obtained.The TBDI/tris（8-hydroxyquinoline） aluminum（Alq_3） OLED device exhibits a comparable external quantum efficiency and current efficiency to a traditional 4,4-bis[N-（l-naphthyl）-N-phenyl-amino]biphenyl（α-NPD）/Alq_3 OLED.A C_（70）-based Schottky junction with 5 wt%-TBDI yields a power conversion efficiency of 5.0%,which is much higher than 1.7%for an α-NPD-based junction in the same configuration.These results suggest that TBDI has some promising properties which are in favor of the hole-transporting in Schottky junctions with a low-concentration donor.

Introduction of F_4-TCNQ/MoO_3 layers for thermoelectric devices based on pentacene

We introduced a dual electron accepting layer composed of tetrafluoro-tetracyanoquinodimethane （F4-TCNQ） and MoO3 for thermoelectric devices based on a pentacene layer. We found that the power factor is enhanced by placing an F4-TCNQ layer directly in contact with the pentacene layer and it is also enhanced by placing a MoO3 layer between the F4-TCNQ layer and the Au electrode. By examining the contact resistance using a field effect transistor and a hole-only diode, we confirmed that the hole injection is improved due to the reduction of contact resistance at the interface between the MoO3 layer and the Au electrode.

Theoretical predication for transition energies of thermally activated delayed fluorescence molecules

Thermally activated delayed fluorescence（TADF） emitters are primarily comprised of intramolecular charge-transfer（ICT） molecules with small energy difference between the lowest singlet and triplet excited states.They lend extremely favorable electroluminescent performance to organic light-emitting diodes（OLEDs）.This paper summarizes relevant issues and research efforts in the theoretical prediction of singlet- and triplet-transition energies of ICT molecules via time-dependent density functional theory（TDDFT）.The successful application of the descriptor-based optimal Hartree-Fock percentage method and the optimally tuned range-separated functional to many TADF systems represent an interesting approach to the exact prediction of the complex excited-state molecular dynamics within TDDFT.

Luminescent Cu(Ⅰ) and Ag(Ⅰ) coordination polymers:Fast phosphorescence or thermally activated delayed fluorescence

By applying two donor-acceptor motif molecules,5,10-di(pyridin-4-yl)-5,10-dihydrophenazine(L1)and 10,10'-di(pyridin-3-yl)-10H,10'H-9,9'-spiroacridine(L2),as ligands and CuI/AgCF3CO2 as metal salt,we synthesized three coordination polymers,namely,{Cu4(L1)2I4}(CP1),{Cu(L2)I·CHCl3}(CP2)and{Ag(L2)CO2CF3·CHCl3}(CP3).X-ray crystallographic analysis revealed that three coordination polymers all feature one-dimensional(1D)linear chains which are consisting of molecular boxlike units.In comparison with low photoluminescence quantum yield(PLQY)of two ligands,three coordination polymers,CP1,CP2 and CP3,present more intense photoluminescence with PLQY of 15%,46%and 34%at room temperature respectively.The PL emission of CP1 and CP2 at room temperature could be attributed to the fast phosphorescence with lifetime both around 5 ms due to effective intersystem crossing(ISC).Whilst,it is worth noting that CP3 exhibit thermally activated delayed fluorescence(TADF)emission at room temperature.