title: Large enhancement in photocurrent by Mn doping in CdSe/ZTO quantum dot sensitized solar cells.
abstract: We find a large enhancement in the efficiency of CdSe quantum dot sensitized solar cells by doping with manganese. In the presence of Mn impurities in relatively small concentrations (2.3%) the photoelectric current increases by up to 190%. The average photocurrent enhancement is about 160%. This effect cannot be explained by a light absorption mechanism because the experimental and theoretical absorption spectra demonstrate that there is no change in the absorption coefficient in the presence of the Mn impurities. To explain such a large increase in the injection current we propose a tunneling mechanism of electron injection from the quantum dot LUMO state to the Zn2SnO4(ZTO) semiconductor photoanode. The calculated enhancement is approximately equal to 150% which is very close to the experimental average value of 160%. The relative discrepancy between the calculated and experimentally measured ratios of the IPCE currents is only 6.25%. For other mechanisms (such as electron trapping, etc.) the remaining 6.25% cannot explain the large change in the experimental IPCE. Thus we have indirectly proved that electron tunneling is the major mechanism of photocurrent enhancement. This work proposes a new approach for a significant improvement in the efficiency of quantum dot sensitized solar cells.
authors.affiliation: Department of Physics and Astronomy/3905, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA. yurid@uwyo.edu.
authors.forename: Artem
authors.initials: A
authors.lastname: Pimachev
authors.affiliation: Department of Physics and Astronomy/3905, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA. yurid@uwyo.edu.
authors.forename: Uma
authors.initials: U
authors.lastname: Poudyal
authors.affiliation: Department of Physics and Astronomy/3905, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA. yurid@uwyo.edu.
authors.forename: Vitaly
authors.initials: V
authors.lastname: Proshchenko
authors.affiliation: Department of Physics and Astronomy/3905, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA. yurid@uwyo.edu.
authors.forename: Wenyong
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Physics and Astronomy/3905, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA. yurid@uwyo.edu.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Dahnovsky