Impact of blocking layer on DSSC performance based on new dye -indolo[3,2,1-jk]carbazole derivative and N719

The impact of the thickness of the TiO 2 blocking layer (50, 150 and 300 nm) on DSSC performance based on a new D-D-π-A architecture of metal-free organic dyes and commercial N719 was investigated. The blocking layers were prepared by atomic layer deposition. New indolo[3,2,1- jk ]carbazole derivatives as sensitizers with a phenothiazine unit and an acetylene linkage containing either an aldehyde or cyanoacrylic acid were designed, synthesized and characterized. However, the lack of anchoring ability of –CHO group with TiO 2 was demonstrated. It was found that the blocking layer thickness has an important role in cell performance. Finally, by the optimum thickness of TiO 2 film being 50 nm, the highest efficiency was achieved at 3.70, 8.49 and 8.05% for DSSC based on indolo[3,2,1- jk ]carbazole derivative, N719 and mixture of these dyes. • New carbazol derivatives with aldehyde or cyanoacrylic acid group were synthesized for dye-sensitized solar cells (DSSCs). • A series of substrates with blocking layer (BL) of different thicknesses using ALD method were prepared. • DSSCs sensitized with N719, carbazole derivative with a cyanoacrylic acid group or mixture of them were fabricated. • The effect of blocking layer BL thickness and applied dyes on photovoltaic response of DSSCs was presented. • The highest efficiency above 8% showed devices with BL thickness of 50 nm containing N719 and a mixture of dyes.