Improved current extraction from ZnO/PbS quantum dot heterojunction photovoltaics using a MoO3 interfacial layer

Publication Type:

Journal Article

Source:

Nano Lett., ACS Publications, Volume 11, Issue 7, p.2955-2961 (2011)

ISBN:

1530-6984

Keywords:

2011, 2013 and earlier

Abstract:

The ability to engineer interfacial energy offsets in photovoltaic devices is one of the keys to their optimization. Here, we demonstrate that
improvements in power conversion efficiency may be attained for ZnO/PbS
heterojunction quantum dot photovoltaics through the incorporation of a
MoO(3) interlayer between the PbS colloidal quantum dot film and the
top-contact anode. Through a combination of current-voltage
characterization, circuit modeling, Mott-Schottky analysis, and external
quantum efficiency measurements performed with bottom- and
top-illumination, these enhancements are shown to stem from the
elimination of a reverse-bias Schottky diode present at the PbS/anode
interface. The incorporation of the high-work-function MoO(3) layer pins
the Fermi level of the top contact, effectively decoupling the device
performance from the work function of the anode and resulting in a high
open-circuit voltage (0.59 ± 0.01 V) for a range of different anode
materials. Corresponding increases in short-circuit current and fill
factor enable 1.5-fold, 2.3-fold, and 4.5-fold enhancements in
photovoltaic device efficiency for gold, silver, and ITO anodes,
respectively, and result in a power conversion efficiency of 3.5 ± 0.4%
for a device employing a gold anode.

Notes:

PMID: 21661734