270 research outputs found
Fast Growth of Thin MAPbI\u3csub\u3e3\u3c/sub\u3e Crystal Wafers on Aqueous Solution Surface for Efficient Lateral-Structure Perovskite Solar Cells
Solar-grade single or multiple crystalline wafers are needed in large quantities in the solar cell industry, and are generally formed by a top-down process from crystal ingots, which causes a significant waste of materials and energy during slicing, polishing, and other processing. Here, a bottom-up technique that allows the growth of wafer-size hybrid perovskite multiple crystals directly from aqueous solution is reported. Single-crystalline hybrid perovskite wafers with centimeter size are grown at the top surface of a perovskite precursor solution. As well as saving raw materials, this method provides unprecedented advantages such as easily tunable thickness and rapid growth of the crystals. These crystalline wafers show high crystallinity, broader light absorption, and a long carrier recombination lifetime, comparable with those of bulk single crystals. Lateral-structure perovskite solar cells made of these crystals demonstrate a record power conversion efficiency of 5.9%.
Includes supplementary materials
The Optical/Near-Infrared Light Curves of SN 2002ap for the First 1.5 Years after Discovery
Late-time BVRIJHK photometry of the peculiar Type Ic SN 2002ap, taken between
2002 June 12 and 2003 August 29 with the MAGNUM telescope, is presented. The
light curve decline rate is derived in each band and the color evolution is
studied through comparison with nebular spectra and with SN 1998bw. Using the
photometry, the OIR bolometric light curve is built, extending from before
light maximum to day 580 after explosion. The light curve has a late-time shape
strikingly similar to that of the hypernova SN 1998bw. The decline rate changes
from 0.018 mag/day between day 130 and 230 to 0.014 mag/day between day 270 and
580. To reproduce the late-time light curve, a dense core must be added to the
1-D hypernova model that best fits the early-time observations, bringing the
ejecta mass from 2.5 Msun to 3 Msun without much change in the kinetic energy,
which is 4 times 10^51 ergs. This is similar to the case of other hypernovae
and suggests asymmetry. A large H-band bump developed in the spectral energy
distribution after about day 300, probably caused by strong [Si I] 1.646 micron
and 1.608 micron emissions. The near-infrared flux contribution increased
simultaneously from 50% at day 580. The near-infrared light curves
were compared with those of other Type Ib/c supernovae, among which SN 1983I
seems similar to SN 2002ap both in the near-infrared and in the optical.Comment: 24pages, 9 figures, ApJ in press (10 June 2006, v644 1 issue).
Acknowledgements update
Low Temperature Solution-Processed Sb:SnO\u3csub\u3e2\u3c/sub\u3e Nanocrystals for Efficient Planar Perovskite Solar Cells
Inorganic metal oxide electron-transport layers (ETLs) have the potential to yield perovskite solar cells with improved stability, but generally need high temperature to form conductive and defect-less forms, which is not compatible with the fabrication of flexible and tandem solar cells. Here, we demonstrate a facile strategy for developing efficient inorganic ETLs by doping SnO2 nanocrystals (NCs) with a small amount of Sb using a low-temperature solution-processed method. The electrical conductivity was remarkably enhanced by Sb-doping, which increased the carrier concentration in Sb:SnO2 NCs. Moreover, the upward shift of the Fermi level owing to doping results in improved energy level alignment, which led to reduced charge recombination, and thus longer electron recombination lifetime and improved open-circuit voltage (VOC). Therefore, Sb-doping of SnO2 significantly enhanced the photovoltaic performance of planar perovskite devices by increasing the fill factor and VOC, and reducing photocurrent hysteresis, extending the potential application of low-temperature-processed ETLs in future flexible and tandem solar cells
The Type Ic Hypernova SN 2003dh/GRB 030329
The spectra of SN 2003dh, identified in the afterglow of GRB030329, are
modeled using radiation transport codes. It is shown that SN 2003dh had a high
explosion kinetic energy ( erg in spherical symmetry),
making it one of the most powerful hypernovae observed so far, and supporting
the case for association between hypernovae and Gamma Ray Bursts. However, the
light curve derived from fitting the spectra suggests that SN 2003dh was not as
bright as SN 1998bw, ejecting only \sim 0.35\Msun of \Nifs. The spectra of SN
2003dh resemble those of SN 1998bw around maximum, but later they look more
like those of the less energetic hypernova SN 1997ef. The spectra and the
inferred light curve can be modeled adopting a density distribution similar to
that used for SN 1998bw at \kms but more like that of SN 1997ef at
lower velocities. The mass of the ejecta is \sim 8\Msun, somewhat less than
in the other two hypernovae. The progenitor must have been a massive star (M
\sim 35-40\Msun), as for other hypernovae. The need to combine different
one-dimensional explosion models strongly indicates that SN 2003dh was an
asymmetric explosion.Comment: 11 pages, 1 table and 5 figures. To appear in the Astrophysical
Journal (Letters). Revised version taking referee's comments into account,
minor change
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