Rational Design of bicarbazoles for the construction of Organic Light-Emitting Diodes (OLEDs)

M. ALEXIA EL AIN; LAUREANO MARÍN OLIVA; MARÍA E. BUDÉN; MARCELO PUIATTI; ROBERTO A. ROSSI.

Viña del Mar

Congreso; ELAFOT XIV; 2019

Universidad Católica de Chile

In order to be suitable for the construction of OLEDs, the organic molecules must gather certain characteristics: high photoluminescence quantum yield (PLQYs), small Singlet- Triplet Energy gap, low molecular flexibility, among others. These properties have a direct impact in the efficiency of the device. Besides, since we are interested in blue OLEDs, the emission fluorescence band should be at approximately 460 nm.In the first place, to avoid the tedious synthesis of a set of molecules, which involves many steps, molecular modeling studies were carried out to choose the better candidates for the construction of the device, taking into account the characteristics mentioned above. We arranged in six groups the different compounds, based on the nucleus of the carbazole or bicarbazole and a suitable acceptor, taking into account all the possible combinations. As a first approximation, we calculated HOMO-LUMO energy difference in the ground state, using DFT and difference energy Singlet-Triplet using TD-DFT. To obtain high PLQYs, it is suggested that the values of these two energies should be small enough (<0.3 eV) in order to achieve thermally activated delayed fluorescence. Here, we present the results of the synthesis of the bicarbazoles (from the respective diarylamines) which exhibited the best molecular properties as suggested by DFT and TD-DFT calculations.