Vapor Deposition of Perovskite Precursor PbI2 on Au and Graphite

MRS Advances ◽  
2020 ◽  
Vol 5 (8-9) ◽  
pp. 403-410
Author(s):  
Benjamin Ecker ◽  
Ke Wang ◽  
Yongli Gao
Keyword(s):  
Energy Level ◽  
Film Formation ◽  
Pyrolytic Graphite ◽  
Photoemission Spectroscopy ◽  
Photovoltaic Devices ◽  
Excessive Iodine ◽  
Energy Level Alignment ◽  
Perovskite Photovoltaic ◽  
Deposition Conditions

AbstractThe energy level alignment that occurs at the interfaces in planar-hetero structured perovskite photovoltaic devices strongly influences the charge transport across the interface, and thus plays a crucial role in overall device performance. To directly observe the energy level alignment requires pristine homogeneous surfaces that are free of contamination including adventitious carbon. Co-evaporation offers the ability to grow perovskite thin films in-situ, and the method involves thermally evaporating the perovskite precursors such as PbI2 and CH3NH3I. Early reports have shown that the perovskite film formation and stoichiometry are problematic at ultralow coverages. In particular, it was reported that there was excessive PbI2 and a deficiency in CH3NH3I. Using photoemission spectroscopy, we investigated the perovskite precursor PbI2 on gold and highly oriented pyrolytic graphite (HOPG) surfaces. Results show that the nature of the surface and the deposition conditions can strongly influence the film formation. Excessive iodine observed in the initial evaporation stages appears to be substrate dependent, and this may influence the overall energy level alignment.

Energy level alignment at interfaces in organic photovoltaic devices

2013 ◽  
Vol 190 ◽  
pp. 12-24 ◽  
Author(s):  
Andreas Opitz ◽  
Johannes Frisch ◽  
Raphael Schlesinger ◽  
Andreas Wilke ◽  
Norbert Koch
Keyword(s):  
Energy Level ◽  
Organic Photovoltaic ◽  
Photovoltaic Devices ◽  
Organic Photovoltaic Devices ◽  
Energy Level Alignment

High efficiency organic–Si hybrid solar cells with a one-dimensional CdS interlayer

Nanoscale ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 4206-4212
Author(s):  
Zhangbo Lu ◽  
Guozhi Hou ◽  
Yu Zhu ◽  
Jiaming Chen ◽  
Jun Xu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Energy Level ◽  
Contact Resistance ◽  
High Efficiency ◽  
Hybrid Solar Cells ◽  
Photovoltaic Devices ◽  
One Dimensional ◽  
Energy Level Alignment

Introducing a CdS NW interlayer: (1) reduces the contact resistance between the rear contact and Si, and (2) optimises the energy level alignment of photovoltaic devices.

scholarly journals Energy-level alignment at interfaces between manganese phthalocyanine and C60

2017 ◽  
Vol 8 ◽  
pp. 927-932 ◽  
Author(s):  
Daniel Waas ◽  
Florian Rückerl ◽  
Martin Knupfer ◽  
Bernd Büchner
Keyword(s):  
Energy Level ◽  
Photoelectron Spectroscopy ◽  
Energy Difference ◽  
Molecular Orbitals ◽  
Organic Photovoltaic ◽  
Photovoltaic Devices ◽  
Organic Photovoltaic Devices ◽  
Energy Level Alignment ◽  
Organic Heterojunctions ◽  
Lowest Unoccupied Molecular Orbitals

We have used photoelectron spectroscopy to determine the energy-level alignment at organic heterojunctions made of manganese phthalocyanine (MnPc) and the fullerene C60. We show that this energy-level alignment depends upon the preparation sequence, which is explained by different molecular orientations. Moreover, our results demonstrate that MnPc/C60 interfaces are hardly suited for application in organic photovoltaic devices, since the energy difference of the two lowest unoccupied molecular orbitals (LUMOs) is rather small.

Interaction and Energy Level Alignment at Interfaces between Pentacene and Low Work Function Metals

2001 ◽  
Vol 708 ◽  
Author(s):  
N. Koch ◽  
J. Ghijsen ◽  
R. Ruiz ◽  
J. Pflaum ◽  
R. L. Johnson ◽  
...  
Keyword(s):  
Energy Level ◽  
Alkali Metal ◽  
Molecular Orbital ◽  
Organic Material ◽  
Alkali Metals ◽  
Energy Gap ◽  
Emission Feature ◽  
Photoemission Spectroscopy ◽  
Energy Level Alignment ◽  
A Charge

ABSTRACTA number of low workfunction metals (samarium, alkali metals) were deposited onto vacuum sublimed thin films of pentacene. The change in the valence electronic structure of the organic material was studied by in situ ultraviolet photoemission spectroscopy (UPS). Alkali metal intercalation leads to the appearance of a new photoemission feature within the pentacene energy gap, due to a charge transfer from the alkali atoms to the lowest unoccupied molecular orbital (LUMO) of the organic material. The energy spacing between this emission feature and the relaxed highest occupied molecular orbital (HOMO) of the pristine molecule is 1 eV. From X-ray photoemission spectroscopy core level analysis, we estimate a concentration ratio of two alkali metal atoms per pentacene molecule at maximum intercalation level, leading to a complete filling of the LUMO. This is consistent with the results from UPS that the new emission is always observed below the Fermi-level. Samarium is found to exhibit a more subtle interaction with pentacene: the molecular orbitals remain almost unperturbed upon Sm deposition. The resulting energy level alignment at this interface seems to be very favorable for the injection of electrons from Sm into pentacene, as the HOMO-onset is found at 1.8 eV below the metal Fermi edge. This value is close to the 2.2 eV HOMO-LUMO gap of pentacene measured by UPS and inverse photoemission spectroscopy, thus corresponding to a small electron injection barrier.

scholarly journals Multication perovskite 2D/3D interfaces form via progressive dimensional reduction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Andrew H. Proppe ◽  
Andrew Johnston ◽  
Sam Teale ◽  
Arup Mahata ◽  
Rafael Quintero-Bermudez ◽  
...  
Keyword(s):  
Dimensional Reduction ◽  
Density Functional ◽  
Grazing Incidence ◽  
Photovoltaic Devices ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Scattering ◽  
Carrier Extraction ◽  
Perovskite Photovoltaic

AbstractMany of the best-performing perovskite photovoltaic devices make use of 2D/3D interfaces, which improve efficiency and stability – but it remains unclear how the conversion of 3D-to-2D perovskite occurs and how these interfaces are assembled. Here, we use in situ Grazing-Incidence Wide-Angle X-Ray Scattering to resolve 2D/3D interface formation during spin-coating. We observe progressive dimensional reduction from 3D to n = 3 → 2 → 1 when we expose (MAPbBr3)0.05(FAPbI3)0.95 perovskites to vinylbenzylammonium ligand cations. Density functional theory simulations suggest ligands incorporate sequentially into the 3D lattice, driven by phenyl ring stacking, progressively bisecting the 3D perovskite into lower-dimensional fragments to form stable interfaces. Slowing the 2D/3D transformation with higher concentrations of antisolvent yields thinner 2D layers formed conformally onto 3D grains, improving carrier extraction and device efficiency (20% 3D-only, 22% 2D/3D). Controlling this progressive dimensional reduction has potential to further improve the performance of 2D/3D perovskite photovoltaics.

Revealing unique energy level alignment at graphene/MoS2 2-dimensional layered junction using in situ ambient pressure x-ray photoelectron spectroscopy

2D Materials ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 045012
Author(s):  
Dong-Jin Yun ◽  
Ane Etxebarria ◽  
Kyung-Jae Lee ◽  
Minsu Seol ◽  
Hae-ryong Kim ◽  
...  
Keyword(s):  
Energy Level ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
X Ray ◽  
Energy Level Alignment
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