TY  - JOUR
A1  - Bäßler, Judith
A1  - Schwarzer, R.
A1  - Kwiatek, P.
A1  - Schröder, K.
A1  - Zhang, J. X.
T1  - The assessment of optimistic self-beliefs : comparison of the german, spanish and chinese versions of the general self-efficacy scale
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Cheng, X.
A1  - Ding, M. D.
A1  - Zhang, J.
A1  - Sun, X. D.
A1  - Guo, Y.
A1  - Wang, Yi-Ming
A1  - Kliem, Bernhard
A1  - Deng, Y. Y.
T1  - Formation of a double-decker magnetic flux rope in the sigmoidal solar active region 11520
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - In this paper, we address the formation of a magnetic flux rope (MFR) that erupted on 2012 July 12 and caused a strong geomagnetic storm event on July 15. Through analyzing the long-term evolution of the associated active region observed by the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, it is found that the twisted field of an MFR, indicated by a continuous S-shaped sigmoid, is built up from two groups of sheared arcades near the main polarity inversion line a half day before the eruption. The temperature within the twisted field and sheared arcades is higher than that of the ambient volume, suggesting that magnetic reconnection most likely works there. The driver behind the reconnection is attributed to shearing and converging motions at magnetic footpoints with velocities in the range of 0.1-0.6 km s(-1). The rotation of the preceding sunspot also contributes to the MFR buildup. Extrapolated three-dimensional non-linear force-free field structures further reveal the locations of the reconnection to be in a bald-patch region and in a hyperbolic flux tube. About 2 hr before the eruption, indications of a second MFR in the form of an S-shaped hot channel are seen. It lies above the original MFR that continuously exists and includes a filament. The whole structure thus makes up a stable double-decker MFR system for hours prior to the eruption. Eventually, after entering the domain of instability, the high-lying MFR impulsively erupts to generate a fast coronal mass ejection and X-class flare; while the low-lying MFR remains behind and continuously maintains the sigmoidicity of the active region.
KW  - Sun: corona
KW  - Sun: coronal mass ejections (CMEs)
KW  - Sun: filaments, prominences
KW  - Sun: magnetic fields
Y1  - 2014
U6  - https://doi.org/10.1088/0004-637X/789/2/93
SN  - 0004-637X
SN  - 1538-4357
VL  - 789
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Kunnus, Kristjan
A1  - Zhang, Wenkai
A1  - Delcey, Mickael G.
A1  - Pinjari, Rahul V.
A1  - Miedema, Piter S.
A1  - Schreck, Simon
A1  - Quevedo, Wilson
A1  - Schröder, Henning
A1  - Föhlisch, Alexander
A1  - Gaffney, Kelly J.
A1  - Lundberg, Marcus
A1  - Odelius, Michael
A1  - Wernet, Philippe
T1  - Viewing the Valence Electronic Structure of Ferric and Ferrous Hexacyanide in Solution from the Fe and Cyanide Perspectives
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - The valence-excited states of ferric and ferrous hexacyanide ions in aqueous solution were mapped by resonant inelastic X-ray scattering (RIXS) at the Fe L-2,L-3 and N K edges. Probing of both the central Fe and the ligand N atoms enabled identification of the metal-and ligand-centered excited states, as well as ligand-to-metal and metal-to-ligand charge-transfer excited states. Ab initio calculations utilizing the RASPT2 method were used to simulate the Fe L-2,L-3-edge RIXS spectra and enabled quantification of the covalencies of both occupied and empty orbitals of pi and sigma symmetry. We found that pi back-donation in the ferric complex is smaller than that in the ferrous complex. This is evidenced by the relative amounts of Fe 3d character in the nominally 2 pi CN- molecular orbital of 7% and 9% in ferric and ferrous hexacyanide, respectively. Utilizing the direct sensitivity of Fe L-3-edge RIXS to the Fe 3d character in the occupied molecular orbitals, we also found that the donation interactions are dominated by sigma bonding. The latter was found to be stronger in the ferric complex, with an Fe 3d contribution to the nominally 5 sigma CN- molecular orbitals of 29% compared to 20% in the ferrous complex. These results are consistent with the notion that a higher charge at the central metal atom increases donation and decreases back-donation.
Y1  - 2016
U6  - https://doi.org/10.1021/acs.jpcb.6b04751
SN  - 1520-6106
VL  - 120
SP  - 7182
EP  - 7194
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Qiu, X. L.
A1  - Wegener, Michael
A1  - Wirges, Werner
A1  - Zhang, X. Q.
A1  - Hillenbrand, J.
A1  - Xia, Zhongfu
A1  - Gerhard, Reimund
A1  - Sessler, G. M.
T1  - Penetration of sulfur hexafluoride into cellular polypropylene films and its effect on the electric charging and electromechanical response of ferroelectrets
N2  - Cellular polypropylene (PP) films were treated with sulfur hexafluoride (SF6) gas in order to study the SF6 penetration behaviour and optimize the electric charging conditions. There were differences in the penetration of SF6 for different cellular PP materials, depending on the microscopic properties, which manifest themselves in the voided structure as well as in the mechanical stiffnesses of the cellular films. The penetration of SF6 after long-term pressure treatment is confirmed in strongly inflated cellular PP films with a low mechanical stiffness of about 1 MPa. No SF6 penetration occurs for slightly inflated cellular PP films with smaller void sizes and higher mechanical stiffnesses of around 5.8 MPa. The observed thickness variations, the higher charging fields during corona charging because of SF6 penetration and the SF6 environment, as well as the resulting electromechanical properties are discussed
Y1  - 2005
SN  - 0022-3727
ER  - 
TY  - JOUR
A1  - Nishikawa, Ken-Ichi
A1  - Hardee, P. E.
A1  - Dutan, I.
A1  - Niemiec, J.
A1  - Medvedev, M.
A1  - Mizuno, Y.
A1  - Meli, A.
A1  - Sol, H.
A1  - Zhang, B.
A1  - Pohl, Martin
A1  - Hartmann, D. H.
T1  - Magnetic agnetic field generation in core-sheath jets via the kinetic Kelvin-Helmholtz instability
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We have investigated magnetic field generation in velocity shears via the kinetic Kelvin-Helmholtz instability (kKHI) using a relativistic plasma jet core and stationary plasma sheath. Our three-dimensional particle-in-cell simulations consider plasma jet cores with Lorentz factors of 1.5, 5, and 15 for both electron-proton and electron-positron plasmas. For electron-proton plasmas, we find generation of strong large-scale DC currents and magnetic fields that extend over the entire shear surface and reach thicknesses of a few tens of electron skin depths. For electron-positron plasmas, we find generation of alternating currents and magnetic fields. Jet and sheath plasmas are accelerated across the shear surface in the strong magnetic fields generated by the kKHI. The mixing of jet and sheath plasmas generates a transverse structure similar to that produced by the Weibel instability.
KW  - acceleration of particles
KW  - magnetic fields
KW  - plasmas
KW  - radiation mechanisms: non-thermal
KW  - relativistic processes
KW  - stars: jets
Y1  - 2014
U6  - https://doi.org/10.1088/0004-637X/793/1/60
SN  - 0004-637X
SN  - 1538-4357
VL  - 793
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Heslop, J. K.
A1  - Winkel, Matthias
A1  - Anthony, K. M. Walter
A1  - Spencer, R. G. M.
A1  - Podgorski, D. C.
A1  - Zito, P.
A1  - Kholodov, A.
A1  - Zhang, M.
A1  - Liebner, Susanne
T1  - Increasing organic carbon biolability with depth in yedoma permafrost
BT  - ramifications for future climate change
JF  - Journal of geophysical research : Biogeosciences
N2  - Permafrost thaw subjects previously frozen organic carbon (OC) to microbial decomposition, generating the greenhouse gases (GHG) carbon dioxide (CO2) and methane (CH4) and fueling a positive climate feedback. Over one quarter of permafrost OC is stored in deep, ice-rich Pleistocene-aged yedoma permafrost deposits. We used a combination of anaerobic incubations, microbial sequencing, and ultrahigh-resolution mass spectrometry to show yedoma OC biolability increases with depth along a 12-m yedoma profile. In incubations at 3 degrees C and 13 degrees C, GHG production per unit OC at 12-versus 1.3-m depth was 4.6 and 20.5 times greater, respectively. Bacterial diversity decreased with depth and we detected methanogens at all our sampled depths, suggesting that in situ microbial communities are equipped to metabolize thawed OC into CH4. We concurrently observed an increase in the relative abundance of reduced, saturated OC compounds, which corresponded to high proportions of C mineralization and positively correlated with anaerobic GHG production potentials and higher proportions of OC being mineralized as CH4. Taking into account the higher global warming potential (GWP) of CH4 compared to CO2, thawed yedoma sediments in our study had 2 times higher GWP at 12-versus 9.0-m depth at 3 degrees C and 15 times higher GWP at 13 degrees C. Considering that yedoma is vulnerable to processes that thaw deep OC, our findings imply that it is important to account for this increasing GHG production and GWP with depth to better understand the disproportionate impact of yedoma on the magnitude of the permafrost carbon feedback.
KW  - permafrost
KW  - carbon
KW  - yedoma
KW  - Alaska
KW  - FT-ICR MS
KW  - microbes
Y1  - 2019
U6  - https://doi.org/10.1029/2018JG004712
SN  - 2169-8953
SN  - 2169-8961
VL  - 124
IS  - 7
SP  - 2021
EP  - 2038
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Fan, Xuanmei
A1  - Scaringi, Gianvito
A1  - Korup, Oliver
A1  - West, A. Joshua
A1  - van Westen, Cees J.
A1  - Tanyas, Hakan
A1  - Hovius, Niels
A1  - Hales, Tristram C.
A1  - Jibson, Randall W.
A1  - Allstadt, Kate E.
A1  - Zhang, Limin
A1  - Evans, Stephen G.
A1  - Xu, Chong
A1  - Li, Gen
A1  - Pei, Xiangjun
A1  - Xu, Qiang
A1  - Huang, Runqiu
T1  - Earthquake-Induced Chains of Geologic Hazards
BT  - Patterns, Mechanisms, and Impacts
JF  - Reviews of geophysics
N2  - Large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking. Most moderate‐ and large‐magnitude earthquakes trigger landslides, ranging from small failures in the soil cover to massive, devastating rock avalanches. Some landslides dam rivers and impound lakes, which can collapse days to centuries later, and flood mountain valleys for hundreds of kilometers downstream. Landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows. Cracks and fractures can form and widen on mountain crests and flanks, promoting increased frequency of landslides that lasts for decades. More gradual impacts involve the flushing of excess debris downstream by rivers, which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency, settlements, ecosystems, and infrastructure. Ultimately, earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales. Two recent events have attracted intense research into earthquake‐induced landslides and their consequences: the magnitude M 7.6 Chi‐Chi, Taiwan earthquake of 1999, and the M 7.9 Wenchuan, China earthquake of 2008. Using data and insights from these and several other earthquakes, we analyze how such events initiate processes that change mountain landscapes, highlight research gaps, and suggest pathways toward a more complete understanding of the seismic effects on the Earth's surface.
KW  - earthquake-induced landslides
KW  - debris flows
KW  - geohazards
KW  - landscape evolution
KW  - sediment cascade
KW  - continental earthquakes
Y1  - 2019
U6  - https://doi.org/10.1029/2018RG000626
SN  - 8755-1209
SN  - 1944-9208
VL  - 57
IS  - 2
SP  - 421
EP  - 503
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Herzschuh, Ulrike
A1  - Cao, Xianyong
A1  - Laepple, Thomas
A1  - Dallmeyer, Anne
A1  - Telford, Richard J.
A1  - Ni, Jian
A1  - Chen, Fahu
A1  - Kong, Zhaochen
A1  - Liu, Guangxiu
A1  - Liu, Kam-Biu
A1  - Liu, Xingqi
A1  - Stebich, Martina
A1  - Tang, Lingyu
A1  - Tian, Fang
A1  - Wang, Yongbo
A1  - Wischnewski, Juliane
A1  - Xu, Qinghai
A1  - Yan, Shun
A1  - Yang, Zhenjing
A1  - Yu, Ge
A1  - Zhang, Yun
A1  - Zhao, Yan
A1  - Zheng, Zhuo
T1  - Position and orientation of the westerly jet determined Holocene rainfall patterns in China
JF  - Nature Communications
N2  - Proxy-based reconstructions and modeling of Holocene spatiotemporal precipitation patterns for China and Mongolia have hitherto yielded contradictory results indicating that the basic mechanisms behind the East Asian Summer Monsoon and its interaction with the westerly jet stream remain poorly understood. We present quantitative reconstructions of Holocene precipitation derived from 101 fossil pollen records and analyse them with the help of a minimal empirical model. We show that the westerly jet-stream axis shifted gradually southward and became less tilted since the middle Holocene. This was tracked by the summer monsoon rain band resulting in an early-Holocene precipitation maximum over most of western China, a mid-Holocene maximum in north-central and northeastern China, and a late-Holocene maximum in southeastern China. Our results suggest that a correct simulation of the orientation and position of the westerly jet stream is crucial to the reliable prediction of precipitation patterns in China and Mongolia.
Y1  - 2019
U6  - https://doi.org/10.1038/s41467-019-09866-8
SN  - 2041-1723
VL  - 10
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Tilmann, F.
A1  - Zhang, Y.
A1  - Moreno, M.
A1  - Saul, J.
A1  - Eckelmann, F.
A1  - Palo, M.
A1  - Deng, Z.
A1  - Babeyko, Andrey
A1  - Chen, K.
A1  - Báez, Juan Carlos
A1  - Schurr, B.
A1  - Wang, R.
A1  - Dahm, Torsten
T1  - The 2015 Illapel earthquake, central Chile: A type case for a characteristic earthquake?
JF  - Geophysical research letters
N2  - On 16 September 2015, the M-W = 8.2 Illapel megathrust earthquake ruptured the Central Chilean margin. Combining inversions of displacement measurements and seismic waveforms with high frequency (HF) teleseismic backprojection, we derive a comprehensive description of the rupture, which also predicts deep ocean tsunami wave heights. We further determine moment tensors and obtain accurate depth estimates for the aftershock sequence. The earthquake nucleated near the coast but then propagated to the north and updip, attaining a peak slip of 5-6 m. In contrast, HF seismic radiation is mostly emitted downdip of the region of intense slip and arrests earlier than the long period rupture, indicating smooth slip along the shallow plate interface in the final phase. A superficially similar earthquake in 1943 with a similar aftershock zone had a much shorter source time function, which matches the duration of HF seismic radiation in the recent event, indicating that the 1943 event lacked the shallow slip.
Y1  - 2016
U6  - https://doi.org/10.1002/2015GL066963
SN  - 0094-8276
SN  - 1944-8007
VL  - 43
SP  - 574
EP  - 583
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Saikin, Anthony
A1  - Jordanova, Vania K.
A1  - Zhang, J. C.
A1  - Smith, C. W.
A1  - Spence, H. E.
A1  - Larsen, B. A.
A1  - Reeves, G. D.
A1  - Torbert, R. B.
A1  - Kletzing, C. A.
A1  - Zhelayskaya, I. S.
A1  - Shprits, Yuri Y.
T1  - Comparing simulated and observed EMIC wave amplitudes using in situ Van
JF  - Journal of Atmospheric and Solar-Terrestrial Physics
N2  - We perform a statistical study calculating electromagnetic ion cyclotron (EMIC) wave amplitudes based off in situ plasma measurements taken by the Van Allen Probes’ (1.1–5.8 Re) Helium, Oxygen, Proton, Electron (HOPE) instrument. Calculated wave amplitudes are compared to EMIC waves observed by the Electric and Magnetic Field Instrument Suite and Integrated Science on board the Van Allen Probes during the same period. The survey covers a 22-month period (1 November 2012 to 31 August 2014), a full Van Allen Probe magnetic local time (MLT) precession. The linear theory proxy was used to identify EMIC wave events with plasma conditions favorable for EMIC wave excitation. Two hundred and thirty-two EMIC wave events (103 H+-band and 129 He+-band) were selected for this comparison. Nearly all events selected are observed beyond L = 4. Results show that calculated wave amplitudes exclusively using the in situ HOPE measurements produce amplitudes too low compared to the observed EMIC wave amplitudes. Hot proton anisotropy (Ahp) distributions are asymmetric in MLT within the inner (L < 7) magnetosphere with peak (minimum) Ahp, ∼0.81 to 1.00 (∼0.62), observed in the dawn (dusk), 0000 < MLT ≤ 1200 (1200 < MLT ≤ 2400), sectors. Measurements of Ahp are found to decrease in the presence of EMIC wave activity. Ahp amplification factors are determined and vary with respect to EMIC wave-band and MLT. He+-band events generally require double (quadruple) the measured Ahp for the dawn (dusk) sector to reproduce the observed EMIC wave amplitudes.
KW  - EMIC waves
KW  - Van Allen Probes
KW  - Linear theory
KW  - Wave generation
Y1  - 2018
U6  - https://doi.org/10.1016/j.jastp.2018.01.024
SN  - 1364-6826
SN  - 1879-1824
VL  - 177
SP  - 190
EP  - 201
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Wang, Y.
A1  - Herzschuh, Ulrike
A1  - Shumilovskikh, L. S.
A1  - Mischke, Steffen
A1  - Birks, H. John B.
A1  - Wischnewski, J.
A1  - Böhner, Jürgen
A1  - Schluetz, F.
A1  - Lehmkuhl, F.
A1  - Diekmann, Bernhard
A1  - Wuennemann, B.
A1  - Zhang, C.
T1  - Open Access Quantitative reconstruction of precipitation changes on the NE Tibetan Plateau since the Last Glacial Maximum - extending the concept of pollen source area to pollen-based climate reconstructions from large lakes
JF  - Climate of the past : an interactive open access journal of the European Geosciences Union
N2  - Pollen records from large lakes have been used for quantitative palaeoclimate reconstruction, but the influences that lake size (as a result of species-specific variations in pollen dispersal patterns that smaller pollen grains are more easily transported to lake centre) and taphonomy have on these climatic signals have not previously been systematically investigated. We introduce the concept of pollen source area to pollen-based climate calibration using the north-eastern Tibetan Plateau as our study area. We present a pollen data set collected from large lakes in the arid to semi-arid region of central Asia. The influences that lake size and the inferred pollen source areas have on pollen compositions have been investigated through comparisons with pollen assemblages in neighbouring lakes of various sizes. Modern pollen samples collected from different parts of Lake Donggi Cona (in the north-eastern part of the Tibetan Plateau) reveal variations in pollen assemblages within this large lake, which are interpreted in terms of the species-specific dispersal and depositional patterns for different types of pollen, and in terms of fluvial input components. We have estimated the pollen source area for each lake individually and used this information to infer modern climate data with which to then develop a modern calibration data set, using both the multivariate regression tree (MRT) and weighted-averaging partial least squares (WA-PLS) approaches. Fossil pollen data from Lake Donggi Cona have been used to reconstruct the climate history of the north-eastern part of the Tibetan Plateau since the Last Glacial Maximum (LGM). The meanannual precipitation was quantitatively reconstructed using WA-PLS: extremely dry conditions are found to have dominated the LGM, with annual precipitation of around 100 mm, which is only 32% of present-day precipitation. A gradually increasing trend in moisture conditions during the Late Glacial is terminated by an abrupt reversion to a dry phase that lasts for about 1000 yr and coincides with "Heinrich event 1" in the North Atlantic region. Subsequent periods corresponding to the Bolling/Allerod interstadial, with annual precipitation (P-ann) of about 350 mm, and the Younger Dryas event (about 270 mm P-ann) are followed by moist conditions in the early Holocene, with annual precipitation of up to 400 mm. A drier trend after 9 cal. ka BP is followed by a second wet phase in the middle Holocene, lasting until 4.5 cal. ka BP. Relatively steady conditions with only slight fluctuations then dominate the late Holocene, resulting in the present climatic conditions. The climate changes since the LGM have been primarily driven by deglaciation and fluctuations in the intensity of the Asian summer monsoon that resulted from changes in the Northern Hemisphere summer solar insolation, as well as from changes in the North Atlantic climate through variations in the circulation patterns and intensity of the westerlies.
Y1  - 2014
U6  - https://doi.org/10.5194/cp-10-21-2014
SN  - 1814-9324
SN  - 1814-9332
VL  - 10
IS  - 1
SP  - 21
EP  - 39
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - GEN
A1  - Schulze, Patricia S. C.
A1  - Bett, Alexander J.
A1  - Bivour, Martin
A1  - Caprioglio, Pietro
A1  - Gerspacher, Fabian M.
A1  - Kabaklı, Özde Ş.
A1  - Richter, Armin
A1  - Stolterfoht, Martin
A1  - Zhang, Qinxin
A1  - Neher, Dieter
A1  - Hermle, Martin
A1  - Hillebrecht, Harald
A1  - Glunz, Stefan W.
A1  - Goldschmidt, Jan Christoph
T1  - 25.1% high-efficiency monolithic perovskite silicon tandem solar cell with a high bandgap perovskite absorber
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Monolithic perovskite silicon tandem solar cells can overcome the theoretical efficiency limit of silicon solar cells. This requires an optimum bandgap, high quantum efficiency, and high stability of the perovskite. Herein, a silicon heterojunction bottom cell is combined with a perovskite top cell, with an optimum bandgap of 1.68 eV in planar p-i-n tandem configuration. A methylammonium-free FA(0.75)Cs(0.25)Pb(I0.8Br0.2)(3) perovskite with high Cs content is investigated for improved stability. A 10% molarity increase to 1.1 m of the perovskite precursor solution results in approximate to 75 nm thicker absorber layers and 0.7 mA cm(-2) higher short-circuit current density. With the optimized absorber, tandem devices reach a high fill factor of 80% and up to 25.1% certified efficiency. The unencapsulated tandem device shows an efficiency improvement of 2.3% (absolute) over 5 months, showing the robustness of the absorber against degradation. Moreover, a photoluminescence quantum yield analysis reveals that with adapted charge transport materials and surface passivation, along with improved antireflection measures, the high bandgap perovskite absorber has the potential for 30% tandem efficiency in the near future.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1197 
KW  - heterojunction silicon solar cells
KW  - interfaces
KW  - perovskite solar cells
KW  - tandem solar cells
KW  - thin films
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-525668
SN  - 1866-8372
IS  - 7
ER  - 
TY  - JOUR
A1  - Stolterfoht, Martin
A1  - Wolff, Christian Michael
A1  - Marquez, Jose A.
A1  - Zhang, Shanshan
A1  - Hages, Charles J.
A1  - Rothhardt, Daniel
A1  - Albrecht, Steve
A1  - Burn, Paul L.
A1  - Meredith, Paul
A1  - Unold, Thomas
A1  - Neher, Dieter
T1  - Visualization and suppression of interfacial recombination for high-efficiency large-area pin perovskite solar cells
JF  - Nature Energy
N2  - The performance of perovskite solar cells is predominantly limited by non-radiative recombination, either through trap-assisted recombination in the absorber layer or via minority carrier recombination at the perovskite/transport layer interfaces. Here, we use transient and absolute photoluminescence imaging to visualize all non-radiative recombination pathways in planar pintype perovskite solar cells with undoped organic charge transport layers. We find significant quasi-Fermi-level splitting losses (135 meV) in the perovskite bulk, whereas interfacial recombination results in an additional free energy loss of 80 meV at each individual interface, which limits the open-circuit voltage (V-oc) of the complete cell to similar to 1.12 V. Inserting ultrathin interlayers between the perovskite and transport layers leads to a substantial reduction of these interfacial losses at both the p and n contacts. Using this knowledge and approach, we demonstrate reproducible dopant-free 1 cm(2) perovskite solar cells surpassing 20% efficiency (19.83% certified) with stabilized power output, a high V-oc (1.17 V) and record fill factor (>81%).
KW  - Energy science and technology
KW  - Solar cells
Y1  - 2018
U6  - https://doi.org/10.1038/s41560-018-0219-8
SN  - 2058-7546
VL  - 3
IS  - 10
SP  - 847
EP  - 854
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Schulze, Patricia S. C.
A1  - Bett, Alexander J.
A1  - Bivour, Martin
A1  - Caprioglio, Pietro
A1  - Gerspacher, Fabian M.
A1  - Kabaklı, Özde Ş.
A1  - Richter, Armin
A1  - Stolterfoht, Martin
A1  - Zhang, Qinxin
A1  - Neher, Dieter
A1  - Hermle, Martin
A1  - Hillebrecht, Harald
A1  - Glunz, Stefan W.
A1  - Goldschmidt, Jan Christoph
T1  - 25.1% high-efficiency monolithic perovskite silicon tandem solar cell with a high bandgap perovskite absorber
JF  - Solar RRL
N2  - Monolithic perovskite silicon tandem solar cells can overcome the theoretical efficiency limit of silicon solar cells. This requires an optimum bandgap, high quantum efficiency, and high stability of the perovskite. Herein, a silicon heterojunction bottom cell is combined with a perovskite top cell, with an optimum bandgap of 1.68 eV in planar p-i-n tandem configuration. A methylammonium-free FA(0.75)Cs(0.25)Pb(I0.8Br0.2)(3) perovskite with high Cs content is investigated for improved stability. A 10% molarity increase to 1.1 m of the perovskite precursor solution results in approximate to 75 nm thicker absorber layers and 0.7 mA cm(-2) higher short-circuit current density. With the optimized absorber, tandem devices reach a high fill factor of 80% and up to 25.1% certified efficiency. The unencapsulated tandem device shows an efficiency improvement of 2.3% (absolute) over 5 months, showing the robustness of the absorber against degradation. Moreover, a photoluminescence quantum yield analysis reveals that with adapted charge transport materials and surface passivation, along with improved antireflection measures, the high bandgap perovskite absorber has the potential for 30% tandem efficiency in the near future.
KW  - heterojunction silicon solar cells
KW  - interfaces
KW  - perovskite solar cells
KW  - tandem solar cells
KW  - thin films
Y1  - 2020
VL  - 4
IS  - 7
PB  - John Wiley & Sons, Inc.
CY  - New Jersey
ER  - 
TY  - JOUR
A1  - Woutersen, Amber
A1  - Jardine, Phillip E.
A1  - Giovanni Bogota-Angel, Raul
A1  - Zhang, Hong-Xiang
A1  - Silvestro, Daniele
A1  - Antonelli, Alexandre
A1  - Gogna, Elena
A1  - Erkens, Roy H. J.
A1  - Gosling, William D.
A1  - Dupont-Nivet, Guillaume
A1  - Hoorn, Carina
T1  - A novel approach to study the morphology and chemistry of pollen in a phylogenetic context, applied to the halophytic taxon Nitraria L.(Nitrariaceae)
JF  - PeerJ
N2  - Nitraria is a halophytic taxon (i.e., adapted to saline environments) that belongs to the plant family Nitrariaceae and is distributed from the Mediterranean, across Asia into the south-eastern tip of Australia. This taxon is thought to have originated in Asia during the Paleogene (66-23 Ma), alongside the proto-Paratethys epicontinental sea. The evolutionary history of Nitraria might hold important clues on the links between climatic and biotic evolution but limited taxonomic documentation of this taxon has thus far hindered this line of research. Here we investigate if the pollen morphology and the chemical composition of the pollen wall are informative of the evolutionary history of Nitraria and could explain if origination along the proto-Paratethys and dispersal to the Tibetan Plateau was simultaneous or a secondary process. To answer these questions, we applied a novel approach consisting of a combination of Fourier Transform Infrared spectroscopy (FTIR), to determine the chemical composition of the pollen wall, and pollen morphological analyses using Light Microscopy (LM) and Scanning Electron Microscopy (SEM). We analysed our data using ordinations (principal components analysis and non-metric multidimensional scaling), and directly mapped it on the Nitrariaceae phylogeny to produce a phylomorphospace and a phylochemospace. Our LM, SEM and FTIR analyses show clear morphological and chemical differences between the sister groups Peganum and Nitraria. Differences in the morphological and chemical characteristics of highland species (Nitraria schoberi, N. sphaerocarpa, N. sibirica and N. tangutorum) and lowland species (Nitraria billardierei and N. retusa) are very subtle, with phylogenetic history appearing to be a more important control on Nitraria pollen than local environmental conditions. Our approach shows a compelling consistency between the chemical and morphological characteristics of the eight studied Nitrariaceae species, and these traits are in agreement with the phylogenetic tree. Taken together, this demonstrates how novel methods for studying fossil pollen can facilitate the evolutionary investigation of living and extinct taxa, and the environments they represent.
KW  - FTIR
KW  - LM
KW  - SEM
KW  - Paratethys
KW  - Tibet
KW  - Sporopollenin
KW  - Mediterranean
KW  - Steppe-desert
KW  - Australia
KW  - Palynology
Y1  - 2018
U6  - https://doi.org/10.7717/peerj.5055
SN  - 2167-8359
VL  - 6
PB  - PeerJ Inc.
CY  - London
ER  -