68 research outputs found
Photovoltaic potential of tin perovskites revealed through layer-by-layer investigation of optoelectronic and charge transport properties
Tin perovskites are the most promising environmentally friendly alternative
to lead perovskites. Among tin perovskites, FASnI3 (CH4N2SnI3) shows optimum
band gap, and easy processability. However, the performance of FASnI3 based
solar cells is incomparable to lead perovskites for several reasons, including
energy band mismatch between the perovskite absorber film and the charge
transporting layers (CTLs) for both types of carriers, i.e., for electrons
(ETLs) and holes (HTLs). However, the band diagrams in the literature are
inconsistent, and the charge extraction dynamics are poorly understood. In this
paper, we study the energy band positions of FASnI3 based perovskites using
Kelvin probe (KP) and photoelectron yield spectroscopy (PYS) to provide a
precise band diagram of the most used device stack. In addition, we analyze the
defects within the current energetic landscape of tin perovskites. We uncover
the role of bathocuproine (BCP) in enhancing the electron extraction at the
fullerene C60/BCP interface. Furthermore, we used transient surface
photovoltage (tr-SPV) for the first time for tin perovskites to understand the
charge extraction dynamics of the most reported HTLs such as NiOx and PEDOT,
and ETLs such as C60, ICBA, and PCBM. Finally, we used Hall effect, KP, and
time-resolved photoluminescence (TRPL) to estimate an accurate value of the
p-doping concentration in FASnI3 and showed a consistent result of 1.5 * 1017
cm-3. Our findings prove that the energetic system of tin halide perovskites is
deformed and should be redesigned independently from lead perovskites to unlock
the full potential of tin perovskites.Comment: 22 pages, 5 figure
Interface Modification for Energy Levels Alignment and Charge Extraction in CsPbI Perovskite Solar Cells
In perovskite solar cells (PSCs) energy levels alignment and charge
extraction at the interfaces are the essential factors directly affecting the
device performance. In this work, we present a modified interface between
all-inorganic CsPbI perovskite and its hole selective contact
(Spiro-OMeTAD), realized by a dipole molecule trioctylphosphine oxide (TOPO),
to align the energy levels. On a passivated perovskite film, by n-Octyl
ammonium Iodide (OAI), we created an upward surface band-bending at the
interface by TOPO treatment. This improved interface by the dipole molecule
induces a better energy level alignment and enhances the charge extraction of
holes from the perovskite layer to the hole transport material. Consequently, a
Voc of 1.2 V and high-power conversion efficiency (PCE) of over 19% were
achieved for inorganic CsPbI perovskite solar cells. Further, to
demonstrate the effect of the TOPO dipole molecule, we present a layer-by-layer
charge extraction study by transient surface photovoltage technique (trSPV)
accomplished by charge transport simulation.Comment: 20 pages, 4 Figure
Effect of Intraduodenal Bile and Na-Taurodeoxycholate on Exocrine Pancreatic Secretion and on Plasma Levels of Secretin, Pancreatic Polypeptide, and Gastrin in Man
The effect of intraduodenally administered cattle bile (CB) and Na-taurodeoxycholate (TDC) on basal pancreatic secretion and plasma levels of secretin, pancreatic polypeptide (PP), and gastrin were investigated on two separate days in 10 fasting volunteers. Doses of 2-6 g CB and 20&600 mg TDC were given intraduodenally at 65-min intervals. Volume, bicarbonate, lipase, trypsin, amylase, and bilirubin were measured in 10-min fractions of duodenal juice, and GI peptides determined by radioimmunoassay. CB and TDC enhanced significantly and dose-dependently volume, bicarbonate and enzyme secretion, and plasma secretin and PP levels. In contrast, plasma gastrin showed only a marginal increase. We conclude that the hydrokinetic effect of intraduodenal CB and TDC is at least partially mediated by secretin. Gastrin could be ruled out as a mediator of the ecbolic effect, whereas other GI peptides, primarily CCK, and/or neural mechanisms must be considered possible mediators. Both pathways may also play a role in the PP release
The Role of Bile in the Regulation of Exocrine Pancreatic Secretion
As early as 1926 Mellanby (1) was able to show that introduction of bile into the duodenum of anesthetized cats produces a copious flow of pancreatic juice. In conscious dogs, Ivy & Lueth (2) reported, bile is only a weak stimulant of pancreatic secretion. Diversion of bile from the duodenum, however, did not influence pancreatic volume secretion stimulated by a meal (3,4). Moreover, Thomas & Crider (5) observed that bile not only failed to stimulate the secretion of pancreatic juice but also abolished the pancreatic response to intraduodenally administered peptone or soap
Three-year performance of the IceAct telescopes at the IceCube Neutrino Observatory
IceAct is an array of compact Imaging Air Cherenkov Telescopes at the ice surface as part of the IceCube Neutrino Observatory. The telescopes, featuring a camera of 61 silicon photomultipliers and fresnel-lens-based optics, are optimized to be operated in harsh environmental conditions, such as at the South Pole. Since 2019, the first two telescopes have been operating in a stereoscopic configuration in the center of IceCube\u27s surface detector IceTop. With an energy threshold of about 10 TeV and a wide field-of-view, the IceAct telescopes show promising capabilities of improving current cosmic-ray composition studies: measuring the Cherenkov light emissions in the atmosphere adds new information about the shower development not accessible with the current detectors. First simulations indicate that the added information of a single telescope leads, e.g., to an improved discrimination between flux contributions from different primary particle species in the sensitive energy range.
We review the performance and detector operations of the telescopes during the past 3 years (2020-2022) and give an outlook on the future of IceAct
- …