Effect of the thieno[3,4-c]pyrrole-4,6-dione on properties of the cyclic thiourea triphenylamine sensitizers

The thieno[3,4-c]pyrrole-4,6-dione (TPD) was applied as an acceptor to insert or replace one ring in the π-linker of the cyclic thiourea triphenylamine dye AZ6. Their light harvest abilities were investigated by UV-vis spectra both in the solution and on the films. The results show that a much higher light absorption abilities have been obtained by the molecular modification. The photovoltaic properties in DSSCs were also evaluated by J-V curves and IPCE measurements. The low photovoltaic conversion efficiencies (PCE) (ST3: 2.29% and ST1: 2.42%) were observed. The improvement PCE of ST2 (3.23%) were realized by further modification of ST1 and verified that the π-π stacking is the main reason to decline the PCE. The theoretical calculation and co-sensitized method were all used to clarify the relationship of molecular structure and properties.