10.1021/jp5004209.s001
Eran Edri
Eran
Edri
Nir Kedem
Nir
Kedem
Hagai Cohen
Hagai
Cohen
Piers Barnes
Piers
Barnes
Gary Hodes
Gary
Hodes
Higher
Open Circuit Voltage and Reduced UV-Induced Reverse Current in ZnO-Based
Solar Cells by a Chemically Modified Blocking Layer
American Chemical Society
2014
FTO substrate
ZnO rods
ZnO layer
Sb ions
uniform layer
Open Circuit Voltage
shunt resistance
leakage
glass substrate
ZnO nanorod growth
ZnO chemical deposition bath
hole conductor
CuSCN hole conductor
UV light
2014-07-31 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Higher_Open_Circuit_Voltage_and_Reduced_UV_Induced_Reverse_Current_in_ZnO_Based_Solar_Cells_by_a_Chemically_Modified_Blocking_Layer/2269855
Solid-state semiconductor-sensitized
solar cells require a thin, dense hole-blocking layer at the conducting
glass substrate (F-doped tin oxide (FTO)) to prevent shorting beween
the FTO and hole conductor. We found that by adding a small amount
of Sb ions to a ZnO chemical deposition bath a thin (few tens of nanometers
thick) dense and uniform layer of Sb-incorporated ZnO forms. Here
we investigate the electronic properties of this layer in comparison
to the continuous ZnO layer at the base of the ZnO rods formed in
the standard preparation. Devices incorporating the Sb-incorporated
dense layer followed by a standard ZnO nanorod growth, onto which
CdS or CdSe was grown followed by a CuSCN hole conductor, showed 100–200
mV higher photovoltage together with occasional improvement in the
short-circuit current. Electrochemical and electrical measurements
indicated complete coverage of the FTO substrate by both preparations;
however, the shunt resistance (resistance to a reverse leakage current)
in the cells (and films) made using the Sb-incorporated ZnO layer
is dramatically increased. Using bias-dependent incident photon-to-electron
conversion efficiency studies, we found that an increased dark or
leakage current develops in the cell on illumination with UV light
together with application of a forward bias. This can be explained
by the presence of a “Schottky junction” at the FTO\ZnO
interface. This increased leakage current is significantly larger
in cells without the Sb-incorporated ZnO compact layer.