Theoretical investigations of the molecular conformation and reorganization energies in the organic diamines as hole‐transporting materials

Abstract

Recently, organic diamine compounds have been widely used as hole‐transporting materials. In this work, DFT B3LYP method with the 6‐31G* basis set was performed to investigate the influence of molecular conformation on the reorganization energy of a series of tetra(aryl)benzidine‐based hole‐transport materials. The results indicate that there are two types (i.e., ISB and BD/TPD) of geometric differences of the organic diamines with the relaxation processes. The reorganization energy of the ISB type is lower than that of the BD/TPD type. For the ISB type, the terminal phenyl moiety of the molecular framework plays an important role in determining the Marcus‐type reorganization energy and the central biphenyl moiety does not. A methyl group attached to a terminal phenyl can be used to tune the reorganization energy. According to the statistical analysis, four geometric parameters could affect the reorganization energy of the BD/TPD type. The conformation of either the central biphenyl or the terminal phenyl moiety of the BD/TPD type determines the Marcus‐type reorganization energy associated with the charge transport process at the molecular level. Presumably, this calculation can be employed to predict the electroluminescence (EL) character of the other organic diamines and to improve the design of new hole‐transporting materials in organic light‐emitting devices (OLEDs). Copyright © 2007 John Wiley & Sons, Ltd.

Push-pull effect on the geometrical, optical and charge transfer properties of disubstituted derivatives of mer-tris(4-hydroxy-1,5-naphthyridinato) aluminum (mer-AlND3)

“…In these calculations only the structural modification of the molecules are considered neglecting the polarization effect in the surrounding medium. The electron/hole transport is predictable from the electron (λ ele )/hole (λ hole ) reorganization energies and in general has good agreement with the experimental observations [27,71,82,[85][86][87][88][89][90][91][92][93][94][95]. Previously the reorganization energies for hole/ electron of mer-Alq3 and its derivatives [56,57,59,61,63] and mer-AlND3 [64] has been calculated at B3LYP/6-31G(D) level.…”

“…Using this model the charge transport that is calculated here is the intermolecular process in which the charge hops between two molecules. The hole and electron transport process at the molecular level in the electroluminescent layer can then be portrayed as the electron transfer/hole transfer reactions between the neighboring molecules as [27,[84][85][86][87][88][89][90][91][92][93][94][95]:…”

Theoretical investigations on electronic structures and photophysical properties of novel bridged triphenylamine derivatives

“…Density functional theory (DFT), due to its feature of including the electronic correlation in a computationally efficient manner, has been widely used in p-conjugated systems including TPA derivatives, and these results are more accurate than those derived from other methods [21][22][23]. Thus, in this work, all the geometries optimization of these bridged TPA derivatives in their neutral, cationic and anionic states were calculated by density functional theory (DFT), B3LYP/6-31G(d).…”

“…According to the IPs and EAs, A 2 , A 3 , A 6 , A 7 , B 2 , B 3 , B 6 , and B 7 exhibit more excellent properties as hole-injection layer material than NPB (a good hole-transporting material proved by theory and experiment (IP, 5.60 eV; EA, 0.22 eV) [23]). Among them, B 2 has the lowest IP value (4.87 eV).…”

Boratome als Spinträger in zwei‐ und dreidimensionalen Systemen

“…von substituierten Benzidinen (II), die zur Lochübertragung in organischen Leuchtdioden dienen. [23] Die Anionenradikale 1 und 2 zeigen langwellige Absorptionen [21] und eine EPR/ENDOR-spektroskopisch erkennbare Spindelokalisierung zu den Borzentren, womit relativ wenig ungepaarte Elektronendichte in den verbrückenden Kohlenstoffringen verbleibt. [12] Tatsächlich üben nur Nitrogruppen einen stärker elektronenziehenden Effekt auf p-Phenylenradikalanionen aus als Dimesitylborylsubstituenten.…”