Chemical-photo-electricity diagrams by Ohm’s law – A case study of Ni-doped TiO2 solutions in dye-sensitized solar cells

•Jsc/Voc in terms of chemical doping and synthesis temperature was derived by Ohm’s law.•Novel chemical-photo-electricity diagrams were constructed based on the proposed model.•Both Jsc and Voc were enhanced in DSSC with a TiO2 (P-25)/Ni-doped TiO2 electrode.

Unlike phase diagrams, which reveal only the chemical equilibrium in a system, starting from Ohm’s law, we constructed chemical-photo-electricity diagrams to display the relationship among materials chemistry, processing conditions of working electrodes, and photo-current/voltage of dye-sensitized solar cells (DSSCs). We derived new equations that quantify the above relationship by using the DSSC with Ni-doped TiO2 solid solution as an example. The same principles and procedures can be applied to construct chemical-photo-electricity diagrams for other solid solutions in not only photo-voltaic like solar cells but also general optoelectronic and electrochemistry research. Besides being a practical tool, these diagrams may also provide opportunities for a new theory that quantitatively couples chemistry with photo-electricity in semiconductors.