A triphenylamine-capped solution-processable wholly aromatic organic molecule with electrochemical stability and its potential application in photovoltaic devices

A triphenylamine-capped solution-processable wholly aromatic conjugated molecule, TPA-TVBP, was designed and synthesized. It exhibited a high thermodynamic stability and good film forming ability as expected, originating from the absence of alkyl and alkoxyl moieties. The triphenylamine cap provided a good solubility because of three-dimensional propeller structure and a donor moiety to construct the organic D-pi-A molecule with the electron-deficient tribenzo[a,c,i]phenazine moiety as the acceptor. The special electrochemical stability was discussed through cyclic voltammetry and potential switching step measurements, and the photocurrent generation in photovoltaic device application was described further. Simple bulk heterojunction photovoltaic cells were fabricated using TPA-TVBP and PCBM, and the higher short circuit current and fill factor than the similar structures were achieved. Based on the mechanism of the photocurrent generation, the TPA-TVBP molecule would be a good model molecule to investigate the electrochemical properties of the triphenylamine-capped material in photovoltaic device application.