Zinc oxide (ZnO) nanowire (NW) based lead sulfide (PbS)
quantum
dot solar cells (QDSCs), i.e., bulk heterojunction QDSCs, have been
widely investigated because of the excellent photoelectronic properties
of PbS QDs and ZnO NWs. To further improve the efficiency of this
type of QDSCs, various passivation methods are applied to ZnO NWs
to suppress interface recombination caused by trap defects. However,
the comparison among passivation using organic, inorganic, and inorganic–organic
hybrid materials with different properties has been less studied.
In this work, the effect of passivation with inorganic Mg-doped ZnO
(ZMO), organic 1,2-ethanedithiol (EDT) and both of them on ZnO NWs
and PbS QDSCs are investigated. As a result, ZnO NWs purely passivated
by organic material EDT show the best performance with fewer surface
defects and better matched energy level with the PbS QD layer. A nearly
1.7 times larger power conversion efficiency (PCE) of 6.9% is achieved
for the solar device using ZnO NW @EDT, compared with that (4.1%)
of the untreated one. The work provides a promising way to impede
interlayer charge recombination and facilitate carrier transport,
thus enhancing the photovoltaic performance of the device.