Hydrogenerated black titanium dioxide-embedded conducting polymer for boosting electron flow in perovskite devices

In this study, black titanium dioxide (B–TiO₂) nanoparticles were synthesised by the hydrogenation of white anatase TiO₂ with the simultaneous formation of oxygen depletion regions. The oxygen deficient regions of B–TiO₂ offer additional energy transport states, which accelerate electron extraction. The B–TiO₂ nanoparticles were introduced into PC₇₀BM as electron transport layer in an inverted perovskite solar cell. The optimised concentration of B–TiO₂ improved the extraction and transport of the electrons, which led to an increased power-conversion efficiency than that of the reference device considered in this study (over 10% enhancement). The role of B–TiO₂ in boosting the electron flow within the device has been elucidated using atomic force microscopy, reflectance, photoluminescence spectroscopy, space-charge-limited current mobility, and electrical impedance. Furthermore, the device stability was influenced by the water-repellent property arising from the self-orientation of PC₇₀BM due to the difference in surface energy.