Current–voltage (I–V) measurements of Ag/n-ZnO have been carried out at temperatures of 200–500 K in order
to understand the temperature dependence of the diode characteristics. Forward-bias
I–V
analysis results in a Schottky barrier height of 0.82 eV and an ideality factor of 1.55
at room temperature. The barrier height of 0.74 eV and Richardson constant of
0.248 A K−2 cm−2
were also calculated from the Richardson plot, which shows nearly
linear characteristics in the temperature range 240–440 K. From the
nkbT/q versus
kbT/q graph, where
n is ideality factor,
kb the Boltzmann
constant, T the
temperature and q
the electronic charge we deduce that thermionic field emission (TFE) is
dominant in the charge transport mechanism. At higher sample temperatures
(>440 K),
a trap-assisted tunnelling mechanism is proposed due to the existence of a deep donor situated at
Ec—0.62 eV
with 3.3 × 10−15 cm2
capture cross section observed by both deep-level transient spectroscopy (DLTS) and
lnI0
versus 1/kbT
plots. The ideality factor almost remains constant in the temperature range 240–400 K,
which shows the stability of the Schottky contact in this temperature range.
Multi-walled carbon nanotube (MWCNT)/TiO2 mesoporous networks can be employed as a new alternative photoanode in dye-sensitized solar cells (DSSCs). By using the MWCNT/TiO2 mesoporous as photoanodes in DSSC, we demonstrate that the MWCNT/TiO2 mesoporous photoanode is promising alternative to standard FTO/TiO2 mesoporous based DSSC due to larger specific surface area and high electrochemical activity. We also show that iron pyrite (FeS2) thin films can be used as an efficient counter electrode (CE), an alternative to the conventional high cost Pt based CE. We are able to synthesis FeS2 nanostructures utilizing a very cheap and easy hydrothermal growth route. MWCNT/TiO2 mesoporous based DSSCs with FeS2 CE achieved a high solar conversion efficiency of 7.27% under 100 mW cm−2 (AM 1.5G 1-Sun) simulated solar irradiance which is considerably (slightly) higher than that of A-CNT/TiO2 mesoporous based DSSCs with Pt CE. Outstanding performance of the FeS2 CE makes it a very promising choice among the various CE materials used in the conventional DSSC and it is expected to be used more often to achieve higher photon-to-electron conversion efficiencies.
Nanoporous and macroporous structures were prepared by using self-assembled monolayer (SAM) onto ZnO thin films in order to investigate the efficiency of dye-sensitized solar cells (DSSCs) produced using these films. Using SAM on ZnO thin films, it is obtained successfully assembled large-area, highly ordered porous ZnO thin films. Varying nanoporous radius is observed between 20 and 50 nm sizes, while it is 500–800 nm for macroporous radius. The solar conversion efficiency of 2.75% and IPCE of 29% was obtained using ZnO nanoporous/N719 dye/I−/I3-electrolyte, while macroporous ZnO given solar conversion efficiency of 2.22% and IPCE of 18%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.