Nonlinear Photocarrier Dynamics and the Role of Shallow Traps in Mixed-Halide Mixed-Cation Hybrid Perovskites

<p>We examine the role of surface passivation on carrier trapping and nonlinear recombination dynamics in hybrid metal-halide perovskites by means of excitation correlation photoluminescence (ECPL) spectroscopy. We find that carrier trapping occurs on subnanosecond timescales in both control (unpassivated) and passivated samples, which is consistent within a shallow-trap model. However, the impact of passivation has a direct effect on both shallow and deep traps. Our results reveal that the effect of passivation of deep traps is responsible for the increase of the carrier lifetimes, while the passivation of shallow traps reduces the excitation density required for shallow-trap saturation. Our work demonstrates how ECPL provides details about the passivation of shallow traps beyond those available via conventional time-resolved photoluminescence techniques.</p>

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Nonlinear photocarrier dynamics and the role of shallow traps in mixed-halide mixed-cation hybrid perovskites

Journal of Materials Chemistry C ◽

10.1039/d1tc01492g ◽

2021 ◽

Author(s):

David Alberto Valverde-Chávez ◽

Esteban Rojas-Gatjens ◽

Jacob Williamson ◽

Sarthak Jariwala ◽

Yangwei Shi ◽

...

Keyword(s):

Surface Passivation ◽

Metal Halide ◽

Carrier Trapping ◽

Mixed Cation ◽

Halide Perovskites ◽

Shallow Traps ◽

Recombination Dynamics

We examine the role of surface passivation on carrier trapping and nonlinear recombination dynamics in hybrid metal-halide perovskites by means of excitation correlation photoluminescence (ECPL) spectroscopy. We find that carrier...

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The Role of Silicon Heterojunction and TCO Barriers on the Operation of Silicon Heterojunction Solar Cells: Comparison between Theory and Experiment

International Journal of Photoenergy ◽

10.1155/2021/6632180 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Yaser Abdulraheem ◽

Moustafa Ghannam ◽

Hariharsudan Sivaramakrishnan Radhakrishnan ◽

Ivan Gordon

Keyword(s):

Solar Cells ◽

Large Scale ◽

Surface Passivation ◽

Series Resistance ◽

Crystalline Silicon ◽

Thermionic Emission ◽

Analytical Description ◽

Theoretical Explanation ◽

The Impact

Photovoltaic devices based on amorphous silicon/crystalline silicon (a-Si:H/c-Si) heterojunction interfaces hold the highest efficiency as of date in the class of silicon-based devices with efficiencies exceeding 26% and are regarded as a promising technology for large-scale terrestrial PV applications. The detailed understanding behind the operation of this type of device is crucial to improving and optimizing its performance. SHJ solar cells have primarily two main interfaces that play a major role in their operation: the transparent conductive oxide (TCO)/a-Si:H interface and the a-Si:H/c-Si heterojunction interface. In the work presented here, a detailed analytical description is provided for the impact of both interfaces on the performance of such devices and especially on the device fill factor ( FF ). It has been found that the TCO work function can dramatically impact the FF by introducing a series resistance element in addition to limiting the forward biased current under illumination causing the well-known S-shape characteristic in the I-V curve of such devices. On the other hand, it is shown that the thermionic emission barrier at the heterojunction interface can play a major role in introducing an added series resistance factor due to the intrinsic a-Si:H buffer layer that is usually introduced to improve surface passivation. Theoretical explanation on the role of both interfaces on device operation based on 1D device simulation is experimentally verified. The I-V characteristics of fabricated devices were compared to the curves produced by simulation, and the observed degradation in the FF of fabricated devices was explained in light of analytical findings from simulation.

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Role of hydrogen bond alternation and charge transfer states in photoactivation of the Orange Carotenoid Protein

Communications Biology ◽

10.1038/s42003-021-02022-3 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Igor A. Yaroshevich ◽

Eugene G. Maksimov ◽

Nikolai N. Sluchanko ◽

Dmitry V. Zlenko ◽

Alexey V. Stepanov ◽

...

Keyword(s):

Crystal Structure ◽

Hydrogen Bond ◽

Charge Transfer ◽

Electric Field ◽

Quantum Chemical ◽

Time Resolved ◽

Bond Alternation ◽

Orange Carotenoid Protein ◽

The Impact

AbstractHere, we propose a possible photoactivation mechanism of a 35-kDa blue light-triggered photoreceptor, the Orange Carotenoid Protein (OCP), suggesting that the reaction involves the transient formation of a protonated ketocarotenoid (oxocarbenium cation) state. Taking advantage of engineering an OCP variant carrying the Y201W mutation, which shows superior spectroscopic and structural properties, it is shown that the presence of Trp201 augments the impact of one critical H-bond between the ketocarotenoid and the protein. This confers an unprecedented homogeneity of the dark-adapted OCP state and substantially increases the yield of the excited photoproduct S*, which is important for the productive photocycle to proceed. A 1.37 Å crystal structure of OCP Y201W combined with femtosecond time-resolved absorption spectroscopy, kinetic analysis, and deconvolution of the spectral intermediates, as well as extensive quantum chemical calculations incorporating the effect of the local electric field, highlighted the role of charge-transfer states during OCP photoconversion.

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Understanding the visible-light photocatalytic activity of GaN:ZnO solid solution: the role of Rh2−yCryO3 cocatalyst and charge carrier lifetimes over tens of seconds

Chemical Science ◽

10.1039/c8sc02348d ◽

2018 ◽

Vol 9 (38) ◽

pp. 7546-7555 ◽

Cited By ~ 14

Author(s):

Robert Godin ◽

Takashi Hisatomi ◽

Kazunari Domen ◽

James R. Durrant

Keyword(s):

Solid Solution ◽

Photocatalytic Activity ◽

Charge Carrier ◽

Water Oxidation ◽

Carrier Lifetime ◽

Time Resolved ◽

Carrier Lifetimes ◽

Charge Carrier Lifetime ◽

Visible Light Photocatalytic

Time-resolved spectroscopies reveals remarkably long charge carrier lifetime in GaN:ZnO solid solution leading to hole accumulation key to water oxidation.

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Protonation of Glutamate 208 Induces the Release of Agmatine in an Outward-facing Conformation of an Arginine/Agmatine Antiporter

Journal of Biological Chemistry ◽

10.1074/jbc.m110.202085 ◽

2011 ◽

Vol 286 (22) ◽

pp. 19693-19701 ◽

Cited By ~ 17

Author(s):

Elia Zomot ◽

Ivet Bahar

Keyword(s):

Binding Pocket ◽

Substrate Binding Pocket ◽

Time Resolved ◽

Extracellular Region ◽

Acidic Conditions ◽

Using Data ◽

Dynamics Simulations ◽

The Impact ◽

First Time

Virulent enteric pathogens have developed several systems that maintain intracellular pH to survive extreme acidic conditions. One such mechanism is the exchange of arginine (Arg+) from the extracellular region with its intracellular decarboxylated form, agmatine (Agm2+). The net result of this process is the export of a virtual proton from the cytoplasm per antiport cycle. Crystal structures of the arginine/agmatine antiporter from Escherichia coli, AdiC, have been recently resolved in both the apo and Arg+-bound outward-facing conformations, which permit us to assess for the first time the time-resolved mechanisms of interactions that enable the specific antiporter functionality of AdiC. Using data from ∼1 μs of molecular dynamics simulations, we show that the protonation of Glu-208 selectively causes the dissociation and release of Agm2+, but not Arg+, to the cell exterior. The impact of Glu-208 protonation is transmitted to the substrate binding pocket via the reorientation of Ile-205 carbonyl group at the irregular portion of transmembrane (TM) helix 6. This effect, which takes place only in the subunits where Agm2+ is released, invites attention to the functional role of the unwound portion of TM helices (TM6 Trp-202–Glu-208 in AdiC) in facilitating substrate translocation, reminiscent of the behavior observed in structurally similar Na+-coupled transporters.

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Abstract 18852: Myofilament Length Dependent Activation: Role of Titin

Circulation ◽

10.1161/circ.130.suppl_2.18852 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Younss AIT MOU ◽

Karen H Hsu ◽

Marion Greaser ◽

Thomas C Irving ◽

Pieter P deTombe

Keyword(s):

Structural Changes ◽

Signal Transduction Pathway ◽

X Ray Diffraction ◽

Thin Filaments ◽

Time Resolved ◽

Myosin Binding Protein ◽

Myosin Binding Protein C ◽

Splice Isoform ◽

The Impact

The cellular basis of the Frank-Starling mechanism is sarcomere length (SL) modulation of myofilament Ca 2+ sensitivity (LDA). The molecular mechanism(s) that underlie LDA are unknown, but recent evidence has implicated the giant protein titin as possible sarcomeric strain sensor responsible for LDA by an, as of yet unidentified, signal transduction pathway. Accordingly, the aim of the present study was to elucidate the impact of SL (from slack=2.0 μm to stretch=2.4 μm) on LDA and sarcomere structure in isolated rat myocardium from either wild-type (WT) or mutant (HM) rats expressing a giant splice isoform of titin. At stretch, WT muscles showed reduced increase in passive tension (-20%) and twitch force (-58%); also, LDA was significantly blunted at the myofilament level. Time-resolved small angle x-ray diffraction of intact twitching muscles during diastole revealed at stretch a significant increase in intensity and spacing of: myosin M2 (+121% & +0.4%) and troponin T3 (+174% & +1.0%); Myosin binding protein C (MyoBPC) also trended to increase (C1%C2). These SL dependent changes in sarcomere structure were absent in HM muscles. Cross-bridge radial spacing (layer line analysis) was significantly reduced at stretch in WT (-8.0%); in HM muscles radial spacing was further, but similarly reduced at both slack and stretch (~-20%). Equatorial spacings and intensity ratios were similar between WT and HM at both slack and stretch. Electron density reconstruction revealed, only in WT, increased mass in both thick and thin filament, and the appearance of an as of yet unidentified moiety spanning the space between the thick and thin filaments at stretch. These results were independently confirmed in skinned myocyte fragments in which endogenous TnC was replaced with fluorescently labelled TnC. Conclusion: Stretch induces structural changes in both thick and thin filaments mediated by titin strain. Moreover, MyoBPC may interact with actin to mediate LDA.

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Intergroup Threat and Outgroup Attitudes

Social Psychology ◽

10.1027/1864-9335/a000127 ◽

2013 ◽

Vol 44 (5) ◽

pp. 311-319 ◽

Cited By ~ 12

Author(s):

Marco Brambilla ◽

David A. Butz

Keyword(s):

Gay Men ◽

Social Group ◽

Welfare Recipients ◽

Intergroup Attitudes ◽

Social Policies ◽

Intergroup Threat ◽

Economic Threat ◽

The Impact ◽

General Climate

Two studies examined the impact of macrolevel symbolic threat on intergroup attitudes. In Study 1 (N = 71), participants exposed to a macrosymbolic threat (vs. nonsymbolic threat and neutral topic) reported less support toward social policies concerning gay men, an outgroup whose stereotypes implies a threat to values, but not toward welfare recipients, a social group whose stereotypes do not imply a threat to values. Study 2 (N = 78) showed that, whereas macrolevel symbolic threat led to less favorable attitudes toward gay men, macroeconomic threat led to less favorable attitudes toward Asians, an outgroup whose stereotypes imply an economic threat. These findings are discussed in terms of their implications for understanding the role of a general climate of threat in shaping intergroup attitudes.

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