Metal-free organic sensitizers with a sterically hindered thiophene unit for efficient dye-sensitized solar cells

Two new organic sensitizers for dye solar cells containing a sterically hindered moiety have been synthesized. The introduction of a 3,4-dibutyl-thiophene ring into D-pi-A dyes reduces the sensitizer aggregation and allows the preparation of solar cells with PCE of 7.17% and 6.27% without the use of coadsorbant agents.