Acetylene-bridged dyes with high open circuit potential for dye-sensitized solar cells
A series of simple metal-free organic dyes MS1-MS3 have been designed and synthesized, and their optical, electrochemical, and photovoltaic properties were investigated. The molecular structures are based on a push-pull framework with a triphenylamine, naphthyldiphenylamine, or anthracenyl diphenylamine as the donor connected to a carboxyphenyl acceptor via a C C bond. The speciality of this new dye design is to obtain higher device open-circuit potentials. The dye-sensitized solar cells using this new sensitizer in combination with I-/I-3(-) exhibited exceptionally high V-OC values of 810, 844, and 866 mV for MS1, MS2, and MS3, respectively. The absorption bands of the anthracene-bridged dye MS3 showed remarkable peak broadening and red shifts due to the strong electronic coupling between the donor and bridge facilitated by the C-C triple bond, significantly promoting the light-harvesting capability. The resulting devices of MS3 showed large IPCE values of 75-80% in the region 370-590 nm, giving J(SC)/mA cm(-2) = 8.16, V-OC/mV = 866, FF = 0.76, and eta = 5.44% under standard AM 1.5G one sun irradiation.