Synthesis and Optical Properties of Bis(oligophenyleneethynylenes)

Synthesis, photophysical and electrochemical properties and DSSC applications of triphenylamine chalcone dendrimers via click chemistry

Fluorene-cored dendrimers containing a triphenylamine chalcone unit at the periphery have been synthesized by click chemistry approach, and their photophysical and electrochemical properties have been investigated.

Pyrene functionalized triphenylamine-based dyes: synthesis, photophysical properties and applications in OLEDs

Pyrene functionalized triphenylamine-based dyes TP, TCP and TCCP were synthesized via alternate Heck and Wittig reactions. It was found that they could emit strong green light with high fluorescence yields because the formation of the excimer from a pyrene unit was suppressed completely. Moreover, the nondoped organic light-emitting diodes using TP, TCP and TCCP as the emitters as well as the hole-transporting materials were fabricated, and gave green electroluminescence. Notably, the device based on TP exhibited good performance with a low turn-on voltage of 2.80 V, a high maximum luminance of 29 880 cd m−2 at 9.5 V, a high current efficiency of 3.34 cd A−1, and a high power efficiency of 2.67 lm w−1. It suggested that pyrene functionalized triphenylamine derivatives may have applications in non-doped OLEDs.

Additional insights into luminescence process of polycyclic aromatic hydrocarbons with carbonyl groups: photophysical properties of secondary N-alkyl and tertiary n,n-dialkyl carboxamides of naphthalene, anthracene, and pyrene

Here we report the substitution effects of N-alkyl and N,N-dialkyl carboxamide groups on the fluorescence properties of polycyclic aromatic hydrocarbon chromophores, so as to control their fluorescence properties. The fluorescence properties of compounds obtained using solvents with different polarities showed very little change, indicating that the modified compounds do not form charge transfer states. TD-DFT calculations and measurements performed at low temperature (78 K) and in viscous solvents revealed that the N-alkyl and N,N-dialkyl carboxamide groups tend to reduce the contributions from intersystem crossing and increase those from internal conversion. Considering that the fluorescence mechanism of low-fluorescence carbonyl compounds such as aldehyde and ketone is dominated by intersystem crossing and that of high-luminescence carbonyl compounds such as carboxylic acid and ester is dominated by a radiative process, it can be said that the photophysical process of N-alkyl and N,N-dialkyl carboxamides is novel. In addition, the calculation results for excited states indicated that such contributions can be controlled by selecting the appropriate polycyclic aromatic hydrocarbon or amide structure, in addition to solvent viscosity and temperature.