Synthesis and photovoltaic properties of new ruthenium(II)-bis(aryleneethynylene) complexes

A new series of small-molecular ruthenium(II)-diynes trans-Ru(dppe) 2(C equivalent to CAr)2 (D1 - D4) (dppe = Ph2CH2CH2Ph2; Ar = aromatic moiety) have been successfully designed, synthesized and characterized by photophysical, electrochemical and computational methods, and complexes D1 and D3 were crystallographically characterized. The optical and time-dependent density functional theory studies showed that the absorption ability of these complexes was significantly enhanced by incorporating the stronger electron-donor groups. The effect of different electron-donor groups in these metalloorganic complexes on the optoelectronic and photovoltaic properties was also examined. In this work, benzothiadiazole as the electron acceptor and triphenylamine and/or thiophene as the electron donor were introduced in these complexes, which were found to have optimal energy bandgaps spanning from 1.70 to 1.83 eV and broad absorption bands within 300-700 nm, rendering them good electron donor materials to blend with [6,6]-phenyl-C-71-butyric acid methyl ester (PC70BM) in the fabrication of the solution-processed bulk heterojunction (BHJ) solar cells. The best power conversion efficiency (PCE) of 0.66% was achieved, which is the highest PCE in ruthenium(II)-containing BHJ solar cells to date. (C) 2017 Elsevier B.V. All rights reserved.