Triphenylamine and some of its derivatives as versatile building blocks for organic electronic applications

Abstract

This review article gives an overview of past and current activities in the Linear Conjugated Systems Group of Angers and in the IPOC – Functional Polymers Group of the Institute of Polymer Chemistry of Stuttgart on the use of triphenylamine (TPA) as versatile building block for organic electronics. In the first part, the properties of TPA itself are introduced including geometrical and energy level considerations. Dimerization of TPA to tetraphenylbenzidine upon electrochemical oxidation is highlighted. The blocking of TPA para‐positions and its implications in terms of electroactivity is further discussed. The second part shows that dimerization of TPA as pendant redox‐active moieties in polymers is a versatile strategy to crosslink polymer films. Coming from redox homopolymers the crosslinking strategy is extended towards conjugated redox polymers based on polythiophenes and block copolymers. Conductivity mechanisms and the influence of doping level on conductivity are probed with cyclic voltammetry coupled with in situ conductance and four‐point probe measurements. The last part is dedicated to the use of TPA as an electron‐donating block in the design of donor‐π‐acceptor chromophores and their use as active material in organic photovoltaics. An overview of some relevant TPA‐based push–pull molecules from the literature and our contribution to this field is presented emphasizing the progress of the photovoltaic performance of organic solar cells made over the last decade. © 2018 Society of Chemical Industry

Unsymmetric Bistable [c2]Daisy Chain Rotaxanes which Combine Two Types of Electroactive Stoppers

“…This becomes obvious by comparing the redox potential of the isolated perylene ( S2 ) and triarylamine ( S4 ) reference compounds (Figure S2) that reveal mid‐point potentials for the oxidation of +0.17 and +0.30 V (both S2 ) and +0.17 V ( S4 ). Due to the blocking of the para ‐positions in the triarylamine stopper no follow‐up reactions such as dimerization occur , . Moreover, the pronounced current amplitude of the reduction of the perylene unit in the reference compound S2 that is about twice the current amplitude of the first oxidation process in S2 (Figure S2a) strongly suggests a two‐electron transfer mechanism for the cathodic process.…”

Impact of the Replacement of a Triphenylamine by a Diphenylmethylamine Unit on the Electrochemical Behavior of Pentaerythritol‐Based Push‐Pull Tetramers

“…Another attractive approach for the obtainment of functionalized triarylamine electroactive surface, as an alternative to electrodeposition from monomer solution, exploits the dimerizing ability of arylamine units just in a post deposition step of pre‐deposited films. In this case the triarylamine unit is present for example as a redox‐active pendant covalently bound to a polymer backbone, acting as a cross‐linker unit upon oxidative triggering, and generating polymer films crosslinked with redox‐active tetraphenylbenzidine (TPB) moieties …”

“…Triphenylamine (TPA) and more generally arylamine derivatives, constitute outstanding building blocks for the preparation of electroactive materials for opto-electronic applications. [1][2][3] In particular, D-π-A push-pull molecules, in which the electrondonating group (D) derived from an arylamine is connected to an electron-withdrawing group (A) through a π-conjugated spacer, have been extensively investigated as efficient donor materials for organic photovoltaics (OPV) [4][5][6][7][8][9][10] and electro-optical applications. [11,12] On the other hand, arylamine derivatives may exhibit a peculiar electrochemical behavior resulting in the molecule dimerization triggered by their chemical oxidation.…”

Bimodal Heterogeneous Functionality in Redox‐Active Conjugated Microporous Polymer toward Electrocatalytic Oxygen Reduction and Photocatalytic Hydrogen Evolution

“…In this work, we have designed and synthesized two redox‐active CMPs (TAPA‐OPE‐mix and TAPA‐OPE‐gly) by integration of N 1, N 1‐bis(4‐aminophenyl)benzene‐1,4‐diamine (TAPA) and substituted oligo‐( p ‐phenyleneethynylenes) (OPEs) (Scheme and Scheme S3, Supporting Information), and these CMPs have shown impressive heterogeneous catalytic activity for electrochemical O 2 reduction and photochemical H 2 evolution reactions. Notably, TAPA is a well‐studied electron donor, also known for the formation of long‐lived charge‐separated species, whereas OPE is a large π‐chromophoric multi‐phenyl system that exhibits high light‐absorbing properties and can act as an electron acceptor. Moreover, asymmetric and symmetric side‐chain substitutions on bola‐amphiphilic OPE struts have resulted in irregular spherical and nanotape morphologies of TAPA‐OPE‐mix and TAPA‐OPE‐gly, respectively.…”

“…In this work, we have designed and synthesized two redoxactive CMPs (TAPA-OPE-mix and TAPA-OPE-gly) by integration of N1,N1-bis(4-aminophenyl)benzene-1,4-diamine (TAPA) and substituted oligo-(p-phenyleneethynylenes)( OPEs) (Scheme 1 and Scheme S3, Supporting Information), and these CMPs have shown impressive heterogeneous catalytic activity for electro-chemicalO 2 reduction and photochemical H 2 evolution reactions. Notably,T APAi sawell-studied electron donor,a lso known for the formation of long-lived charge-separated species, [61,62] whereas OPE is al arge p-chromophoric multi-phenyl system that exhibits high light-absorbing properties and can act as an electron acceptor.M oreover,a symmetric and symmetric side-chain substitutions on bola-amphiphilic OPE struts have resulted in irregular spherical and nanotape morphologies of TAPA-OPE-mix and TAPA-OPE-gly,r espectively.T he TAPA-OPE-gly is found to be more hydrophilic than TAPA-OPEmix owing to the presence of the di-glycol side chain, as provenb ys olventa dsorption, resulting in better electro-and photocatalytic activities. Furthermore, in situ stabilization of platinum nanoparticleso nb oth CMPs resulted in Pt@CMP nanocomposites showing significantly higher H 2 evolution compared with the pristine CMPs.…”