Abstract
In recent years, fabricating plastic perovskite solar cells (PSCs) becomes increasingly attractive because of their light-weight and bendability. However, commercial plastic substrate like Indium Tin Oxide-polyethylene naphthalate (ITO-PEN) substrate cannot endure in high temperature and acidic condition, which are safe while making PSC on glass substrate. Previously, our group developed an electrodeposition technology to replace commonly-used spin coating to deposit more compact and thinner hole blocking TiOx layer at ambient temperature. In this research, modified electrodeposition is developed to deposit TiOx blocking layer (ED-BL) on ITO-PEN. As to scaffold layer, commercial brookite slurry are used to substitute conventional anatase slurry, because brookite slurry does not require high temperature post-treatment to remove binder so that entire process to be available below 150 oC. However, ITO-PEN is easily corroded in acidic solution bath with pH value below 3. Here, we adjusted the pH value to 4.8 and applied EDTA to solution bath to prevent particle aggregation and make the solution be suitable for ITO-PEN substrate. For brookite slurry, the XRD pattern evidenced that brookite crystal can be formed after annealing at 70 °C. Sheet-like structure of brookite particles with particle size between 16-18 nm was investigated by TEM, which was believed to provide more contact area with near particles, benefiting electron transfer. After process optimization, the flexible device fabricated in low temperature showed a champion photovoltaic efficiency of 15.76%.