As compared with either the temperature-elevated immersion
dyeing process or fast dyeing methods mentioned above, the
solution dropping method reported herein is an easier, greener
(less chemical waste), and more reliable TiO2 dyeing method.
A very short period of time (5 min) and minimum dye solution
(≤30 μL) are required in the solution dropping process of
dyeing TiO2 electrodes (with an active area of 0.4 cm × 0.4
cm). There is nearly no organic solvent waste or leftover dye
substance from such a solution dropping method. Neither
complicated equipment nor extra investment is needed.
Moreover, low solubility dye substances, which are easily
precipitated or aggregated inside the nanoporous TiO2
electrode, are compatible with the solution dropping method,
and hence, high PCEs are within reach