Partially Oxygen-Bridged Triphenylamines with a Quasiplanar Structure as a Key Scaffold for Hole-Transporting Materials

Abstract

Organic electronics have attracted much attention as they promise great potential for applications as lightweight and exible electronic devices. In order to improve the performance of such devices, the development of improved charge transporting materials is of paramount importance. The molecular design of such materials should aim to control not only the electronic structure, but also the molecular orientation of these compounds in the solid state. For the development of materials with improved charge transporting properties, we focused on compounds with a quasiplanar structure, i.e. a structure that is slightly twisted from planarity. As a model skeleton, we designed and synthesized partially oxygen bridged triarylamines. On the basis of their quasiplanar skeletons as key units, we have developed hole transporting materials (HTMs) that were subsequently used in organic electronics devices, such as OLEDs and perovskite solar cells, and led to improved performances. This account article illustrates our endeavors regarding the development of such functional π conjugated materials, with a focus on facile and ef cient synthetic strategies.

Influence of Alkoxy Chain Length on the Properties of Two‐Dimensionally Expanded Azulene‐Core‐Based Hole‐Transporting Materials for Efficient Perovskite Solar Cells

“…[28] To explore high-performance HTMsa nd broaden the pool of candidate molecules,w ep reviously focusedo nq uasiplanar, partiallyo xygen-bridged triarylamines. [29][30][31][32][33] We previously reportedt he synthesis of as heet-shaped structure in which four oxygen-bridged triarylaminesb earing n-octyloxy groups are attachedt oa zulene, an on-benzenoid aromatic hydrocarbon (Azu-Oct). [30] The performances of the PSCs prepared with Azu-Oct as the HTM were found to exceed those fabricated from spiro-OMeTAD under the same conditions (PCE = 15.7 vs. 13.6 %).…”

“…To explore high‐performance HTMs and broaden the pool of candidate molecules, we previously focused on quasiplanar, partially oxygen‐bridged triarylamines . We previously reported the synthesis of a sheet‐shaped structure in which four oxygen‐bridged triarylamines bearing n ‐octyloxy groups are attached to azulene, a non‐benzenoid aromatic hydrocarbon ( Azu‐Oct ) .…”

Synthesis of Azole-fused Benzothiadiazoles as Key Units for Functional π-Conjugated Compounds

“…Moreover, in thiazole-fused BT units, the electronic structure could be further modulated by varying the oxidation state of the sulfur atom in methylthio group at the fused thiazole ring. A variety of D-A molecules and polymers would be developed using these electron-accepting units by combining with various electron-donating and -conjugated units [25][26][27][28][29][30][31][32], which is currently in progress in our laboratory.…”

Hole-Transporting Polymers Containing Partially Oxygen-Bridged Triphenylamine Units and Their Application for Perovskite Solar Cells

“…The synthetic routes to the target polymers are shown in Scheme 1. Monobromo intermediate 1 and 2-decyltetradecyl bromide 2 were synthesized according to previously reported procedures [33,39]. 2-Decyltetradecylmagnesium bromide Grignard reagent was prepared from 2-decyltetradecyl bromide 2 and was converted to 3 by Kumada-Tamao coupling reaction.…”

“…We have recently developed an original πconjugated skeleton in which three phenyl groups are constrained in a quasiplanar fashion by two oxygen bridges [32][33][34][35][36][37][38]. The more planar geometry compared to the propeller-like triarylamines is desirable as it facilitates π-conjugation over the entire skeleton.…”