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

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