Spectral sensitization of TiO2 with electrodeposited PbSe: improvement of photocurrent stability and light conversion efficiency

This work focuses on spectral sensitization of mesoporous TiO 2 films and Nb-doped TiO 2 films with polydisperse PbSe nanoparticles (TiO 2 /PbSe). For this, PbSe was electrochemically deposited from aqueous solution containing Pb 2+ cations and SeO 2 . Chemical amount of electrodeposited PbSe was controlled by deposition time and impacted on the magnitude of sensitized photocurrents. The efficacy of different ions (S n 2− ; I 3 − ; H 2 PO 4 − ; N 2 H 5 + ; SO 3 2− ; SCN − , SeSO 3 2− ) as hole scavengers for TiO 2 /PbSe photoanodes was assessed by dynamics of photocurrent in polarization measurements. Electrolyte of Na 2 SO 3 and Na 2 SeSO 3 is reported as an effective one to attain stable photocurrent. Photoelectrochemical cells with TiO 2 /PbSe photoanodes show solar to electricity conversion efficiency of 0.09%, in spectral region up to 700 nm for undoped TiO 2 . Enhancement of the photoresponse was achieved by different level of Nb doping into mesoporous TiO 2 film. Extension of spectral response up to 800 nm and photocurrent conversion efficiency of 0.24% is observed for TiO 2 /PbSe photoanodes with 2.5 at% Nb-doped TiO 2 . Doping with Nb results in positive shift on electrochemical scale of conduction band of TiO 2 . It favors the collection of photoelectrons from PbSe nanoparticles that have light absorption in wider spectral region.