C3N4 interlayer formation while synthesizing black titania and their dye sensitized solar cell and conductivity performances

Black titania is an attractive applicant as a narrow bandgap absorber in photovoltaic cells. However, the non-equivalency between the amount of visible light absorbed and the photocatalytic activities limits its usage as photoanodes in the dye sensitized solar cells (DSSCs). Herein, the synthesized black titania (BT) via imidazole at 400oC; without washing steps, produces not only Ti2O3 and Ti3O5 nanoparticles but also allows the formation of the C3N4 nanosheets; which is emphasized via XRD, TEM-SAED-IFFT, FTIR, CV and XPS studies. The BT incorporated with hole transporting metals including Ag2O, CuO and Ag2S; at 3% loading, synthesized by deposition precipitation route are also fabricated to form p-n junction interfaces. The best conversion efficiency attained when using Ag2O/BT was 6%; that presented the highest IPCE% in the visible light margin of 500–750 nm, followed by CuO (5.6%) and BT (4.9%). Although Ag2O/BT did not absorb visible light as CuO, however, it offers minimum optical and electronic losses. Besides, it gives the highest dielectric constant (ε′) value subsequent BT and exposes numerous active sites. Well correlations with vibrational, surface texturing, permittivity and electrical conductivity were achieved and discussed to have a view on the effect of the C3N4 interface as well as oxygen defect sites and the incorporation with metal oxide/sulfide groups. This work supplies a new aspect in the synthesis of g-C3N4 while synthesizing the oxygen deficient TiO2-x in solar energy conversion reactions.