Theoretical Studies on Charge Transfer Properties of Carbazole Derivative DiPICz

Abstract

Organic π-conjugated semiconductor materials have been extensively used in organic light-emitting diodes(OLEDs).Among them,carbazole derivatives are commonly used as hole-transporting materials.Here,the electronic structure and transport properties of dibenzo[2,3∶ 5,6]pyrrolizino[1,7-bc]-indolo-[1,2,3-lm]carbazole(DiPICz) were investigated systematically by means of semiclassical Marcus charge transfer theory at the density functional theory level.The results indicate that the mobility of electron is 5.81 × 10-2 cm2·V-1·s-1,which is two orders of magnitude higher than that of hole(6.02×10-4 cm2·V-1·s-1),indicative of abnormal electron-transporting materials.We further proved that both the small electron internal reorganization energies and the character of higher-order molecular packing in its single crystals were crucial to good electron transport properties.In the 'herringbone' packing of DiPICz crystal,the presence of typical slipped face-to-face packing and the formation of weak hydrogen bonds such as C—H…N and C—H…π interactions cause two dimensional electron transport networks,which play an important role in electron transport.