Interesting question, doping TiO2 with Yttrium can enhance

electron extraction and transport as explained by Yang et al,

Interface engineering of highly efficient perovskite solar cells

http://yylab.seas.ucla.edu/papers/Science-2014-Zhou-542-6.pdf

Indirect approach to make injection from TiO2 more favorable was the reduction of ITO work function by spin coating thin film of Polyethylenimine solution, in same paper. 

However, challenge will be to have the additives which can be stable at curing temperature of 450-500C for TiO2, in above example curing was done at 100-150C for TiO2 depending on the nature.

Hi Prashanta:

I have just noticed this paper, ChemSusChem, 2015, 8, 2392-2398 on Nb doping of TiO2 for perovskite solar cells. You might want to have a look.

Good luck!

Sanjib

Thank You Sanjib.