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

Abstract

This work focuses on spectral sensitization of mesoporous TiO2 films and Nb-doped TiO2 films with polydisperse PbSe nanoparticles (TiO2/PbSe). For this, PbSe was electrochemically deposited from aqueous solution containing Pb2+ cations and SeO2. 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(-); H2PO4-; N2H5+; SO32-; SCN-, SeSO32-) as hole scavengers for TiO2/PbSe photoanodes was assessed by dynamics of photocurrent in polarization measurements. Electrolyte of Na2SO3 and Na2SeSO3 is reported as an effective one to attain stable photocurrent. Photoelectrochemical cells with TiO2/PbSe photoanodes show solar to electricity conversion efficiency of 0.09%, in spectral region up to 700 nm for undoped TiO2. Enhancement of the photoresponse was achieved by different level of Nb doping into mesoporous TiO2 film. Extension of spectral response up to 800 nm and photocurrent conversion efficiency of 0.24% is observed for TiO2/PbSe photoanodes with 2.5 at% Nb-doped TiO2. Doping with Nb results in positive shift on electrochemical scale of conduction band of TiO2. It favors the collection of photoelectrons from PbSe nanoparticles that have light absorption in wider spectral region.