Memory seeds enable high structural phase purity in 2D perovskite films for high-efficiency devices

Abstract Two-dimensional (2D) perovskites are a class of halide perovskites offering a pathway for realizing efficient and durable optoelectronic devices. However, the broad chemical phase space and lack of understanding of film formation have led to quasi-2D perovskite films with polydispersity in perovskite layer thicknesses, which have hindered devices performance and stability. Here, we demonstrate a scalable approach involving dissolution of single-phase crystalline powders with homogeneous perovskite layer thickness in desired solvents, to fabricate 2D perovskite thin-films with high phase purity. In-situ characterizations reveal the presence of sub-micron-sized seeds in solution that preserve the memory of the dissolved single-crystals and dictate the nucleation and growth of grains with identical thickness of the perovskite layers in thin-films. Photovoltaic devices fabricated with such films, yields an efficiency of 17.1% and 1.20V open-circuit voltage, while preserving 97.5% of their peak-performance after 800 hours under illumination without any external thermal management.

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Perovskite-molecule composite thin films for efficient and stable light-emitting diodes

Nature Communications ◽

10.1038/s41467-020-14747-6 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 5

Author(s):

Heyong Wang ◽

Felix Utama Kosasih ◽

Hongling Yu ◽

Guanhaojie Zheng ◽

Jiangbin Zhang ◽

...

Keyword(s):

Thin Films ◽

High Efficiency ◽

Light Emitting Diodes ◽

Degradation Mechanism ◽

Deep Understanding ◽

Significant Progress ◽

High Quality ◽

Composite Thin Films ◽

Light Emitting

AbstractAlthough perovskite light-emitting diodes (PeLEDs) have recently experienced significant progress, there are only scattered reports of PeLEDs with both high efficiency and long operational stability, calling for additional strategies to address this challenge. Here, we develop perovskite-molecule composite thin films for efficient and stable PeLEDs. The perovskite-molecule composite thin films consist of in-situ formed high-quality perovskite nanocrystals embedded in the electron-transport molecular matrix, which controls nucleation process of perovskites, leading to PeLEDs with a peak external quantum efficiency of 17.3% and half-lifetime of approximately 100 h. In addition, we find that the device degradation mechanism at high driving voltages is different from that at low driving voltages. This work provides an effective strategy and deep understanding for achieving efficient and stable PeLEDs from both material and device perspectives.

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Electrical Transport and In-Situ X-Ray Studies of the Formation of TiSi2 Thin Films on Si

MRS Proceedings ◽

10.1557/proc-77-737 ◽

1986 ◽

Vol 77 ◽

Cited By ~ 5

Author(s):

J. C. Hensel ◽

J. M. Vandenberg ◽

L. F. Mattheiss ◽

F. C. Unterwald ◽

A. Maury

Keyword(s):

Thin Films ◽

Electrical Transport ◽

Structural Phase ◽

X Ray Diffraction ◽

Metallic Behavior ◽

Distinctive Features ◽

X Ray ◽

Total Energies ◽

Sputter Deposited

ABSTRACTThe formation of TiSi2 thin films on Si has been investigated by in situ x-ray diffraction and by electrical transport. The x-ray results show unequivocally that the staging proceeds through two orthorhombic polytypes of TiSi2 according to the sequence: sputter-deposited metallic Ti films on Si (001) → TiSi2 (C49 structure) → TiSi2 (C54 structure), with no evidence of lower suicides. Electrical transport shows metallic behavior for all phases and distinctive features in the annealing curves which correlate with the structural transformations. Most importantly, the resistivity, characteristically very high for the C49 phase, undergoes a precipitous drop at the C49 → C54 transition. Total energies for both phases are calculated and, consistent with the occurrence of a structural phase transformation, are found not to differ appreciably.

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Влияние структурных свойств на электросопротивление тонких пленок Al/Ag в процессе твердофазной реакции

Физика твердого тела ◽

10.21883/ftt.2020.04.49130.652 ◽

2020 ◽

Vol 62 (4) ◽

pp. 621

Author(s):

Р.Р. Алтунин ◽

Е.Т. Моисеенко ◽

С.М. Жарков

Keyword(s):

Thin Films ◽

Solid State ◽

Solid State Reaction ◽

Structural Phase ◽

Diffraction Method ◽

Atomic Ratio ◽

Reaction Process ◽

Russian Science ◽

Reaction Initiation

Based on the study of a solid-state reaction process in Al/Ag thin films (the atomic ratio being Al:Ag=1:3) carried out by in situ electron diffraction method and electrical resistivity measurements, the reaction initiation temperature has been determined and a model of structural phase transitions occurring during the solid-state reaction has been proposed. The solid-state reaction begins at 70°C with the formation of an Al-Ag solid solution at the interface of aluminum and silver nanolayers. It has been found that in the reaction process intermetallic compounds γ-Ag2Al => µ-Ag3Al are successively formed. It has been established that for the formation of the µ-Ag3Al phase in thin films (up to 100 nm) the following is necessary: first, significant excess of silver over aluminum in the atomic composition, second, the formation of the µ-Ag3Al phase begins only after all the FCC aluminum has reacted. The work was supported by the Russian Science Foundation (grant #18-13-00080).

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Структурные фазовые превращения при твердофазной реакции в тонких двухслойных пленках Al/Pt

Физика твердого тела ◽

10.21883/ftt.2018.07.46130.352 ◽

2018 ◽

Vol 60 (7) ◽

pp. 1397

Author(s):

Р.Р. Алтунин ◽

Е.Т. Моисеенко ◽

С.М. Жарков

Keyword(s):

Thin Films ◽

Electron Diffraction ◽

Phase Transformations ◽

Solid Phase ◽

Structural Phase ◽

Solid Phase Reaction ◽

Phase Reaction ◽

Formation Heat ◽

Structural Phase Transformations

AbstractA sequence of phases forming during the solid-phase reaction in Al/Pt bilayer thin films has been investigated by in situ electron diffraction. It is shown that the amorphous PtAl_2 phase forms first during the solid-phase reaction initiated by heating. Upon further heating, PtAl_2, Pt_2Al_3, PtAl, and Pt_3Al crystalline phases sequentially form, which is qualitatively consistent with an effective formation heat model. The content of phases forming during the reaction has been quantitatively analyzed and the structural phase transformations have been examined.

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Investigation of High-Efficiency Vibration Energy Transducer with Dual-Modal ZnO Piezoelectric Thin Films

MRS Proceedings ◽

10.1557/opl.2014.333 ◽

2014 ◽

Vol 1604 ◽

Author(s):

Ying-Chung Chen ◽

Wei-Tsai Chang ◽

Chien-Chuan Cheng ◽

Chun-Kai Mao ◽

Kuo-Sheng Kao

Keyword(s):

Thin Films ◽

Stainless Steel ◽

Piezoelectric Transducer ◽

High Performance ◽

High Efficiency ◽

Stainless Steel Substrate ◽

Steel Substrate ◽

Open Circuit ◽

Piezoelectric Thin Films ◽

Cantilever Length

ABSTRACTThis paper reports a novel means of integrating a high-performance dual-modal ZnO piezoelectric transducer with a flexible stainless steel substrate (SUS304) to construct dual-modal vibration-power transducers. To fabricate vibration-power transducers, the off-axis RF magnetron sputtering method for the growth of ZnO piezoelectric thin films is adopted. The stainless steel substrate has a higher Young’s modulus than those of the other substrates, and behaves the long-term stability under vibration. The transducer includes a ZnO piezoelectric thin film deposited on the stainless steel substrate combined with Pt/Ti layers at room temperature, which is fabricated by an RF magnetron two-step sputtering system. In this report, the ZnO piezoelectric thin films deposited with the tilting angle of 34° are set by controlling the deposition parameters. Scanning electron microscopy and X-ray diffraction of ZnO piezoelectric thin films reveal a rigid surface structure and a high dual-modal orientation. To investigate the generating characteristics of the dual-modal transducer, two basic experiments of longitudinal and shear modes are carried out. Based on cantilever vibration theory, the cantilever length of 1 cm and a vibration area of 1 cm2 are used to fabricate a transducer with a low resonant-frequency of 65 Hz for the natural vibration. A mass loading at the front-end of the cantilever is critical to increase the amplitude of vibration and the power generated by the piezoelectric transducer. The maximum open circuit voltage of the power transducer is 19.4 V.

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Reveal the large open-circuit voltage deficit of all-inorganic CsPbIBr2 perovskite solar cells

Chinese Physics B ◽

10.1088/1674-1056/ac464b ◽

2021 ◽

Author(s):

Ying Hu ◽

Jiaping Wang ◽

Peng Zhao ◽

Zhenhua Lin ◽

Siyu Zhang ◽

...

Keyword(s):

Solar Cells ◽

High Efficiency ◽

Open Circuit Voltage ◽

Perovskite Solar Cells ◽

Open Circuit ◽

Transport Layer ◽

Electron Transport Layer ◽

Perovskite Layer ◽

Excellent Thermal Stability ◽

Voltage Loss

Abstract Due to excellent thermal stability and optoelectronic properties, all-inorganic perovskite is one of the promising candidates to solve the thermal decomposition problem of conventional organic-inorganic hybrid perovskite solar cells (PSCs), but the larger voltage loss (V loss) cannot be ignored, especially CsPbIBr2, which limits the improvement of efficiency. To reduce the V loss, one promising solution is the modification of the energy level alignment between perovskite layer and adjacent charge transport layer (CTL), which can facilitate charge extraction and reduce carrier recombination rate at perovskite/CTL interface. Therefore, the key issues of minimum V loss and high efficiency of CsPbIBr2-based PSCs were studied in terms of the perovskite layer thickness, the effects of band offset of CTL/perovskite layer, the doping concentration of the CTL, and the electrode work function in this study based on device simulations. The open-circuit voltage (V oc) is increased from 1.37 V to 1.52 V by replacing SnO2 with ZnO as electron transport layer (ETL) due to more matching conduction band with CsPbIBr2 layer.

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Eye in the process: Formation of “triple cation” perovskite thin films rationalized by in-situ optical monitoring

10.21203/rs.3.rs-102041/v1 ◽

2020 ◽

Author(s):

Aboma Merdasa ◽

Carolin Rehermann ◽

Katrin Hirselandt ◽

Jinzhao Li ◽

Oliver Maus ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Fiber Optics ◽

Spin Coating ◽

Film Formation ◽

Complementary Information ◽

Optical Process ◽

Process Formation ◽

Film Thinning

Abstract Record performance Metal-Halide Perovskite (MHP) based solar cells have been achieved by incremental optimization of deposition procedures based on spin-coating. We here provide unprecedented insight into the formation process of MHP thin films of the “triple cation” (Cs,MA,FA)Pb(Br,I)3 perovskite from multi-modal in-situ optical process monitoring during spin-coating and annealing. This report details small-footprint fiber-optics based optical spectroscopy setup that enables monitoring of thin-film formation processes by UV-Vis reflectance and photoluminescence spectroscopy with a sub-second time resolution. Complementary information can be obtained from optical features during different stages of film formation: 1) During the first, flow regime dominated, stage of spin-coating, the wet-film thinning can be analyzed from UV-Vis interference, 2) the onset of bulk perovskite formation is clearly observed from the evolution of the semiconductor absorption edge, and 3) Photoluminescence (PL) measurements provide complementary information on nucleation and growth processes. We here provide a comprehensive picture that rationalizes the conditions to obtain a high quality “triple cation” perovskite thin-film during spin-coating and subsequent annealing.

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Laser Deposition of CdS Thin films on Various Substrates

MRS Proceedings ◽

10.1557/proc-201-171 ◽

1990 ◽

Vol 201 ◽

Cited By ~ 1

Author(s):

L. Shi ◽

Y. Hashishin ◽

S. Y. Dong ◽

H. S. Kwok

Keyword(s):

Thin Films ◽

Film Formation ◽

Laser Deposition ◽

Laser Evaporation ◽

Superconducting Transition ◽

X Ray Diffraction ◽

Electrical Measurements ◽

Cds Thin Films ◽

Cds Films

AbstractWe have deposited CdS thin films onto substrates such as glass, sapphire and high Tc YBCO superconducting films by Nd:YAG laser evaporation in a vacuum environment. X-ray diffraction, optical and electrical measurements were used to study the deposited CdS films. The films are highly oriented with c-axis perpendicular to the surface and are optically smooth. The effects of laser fluence, substrate temperature on the film quality will be discussed. Additionally, Indium doped CdS films were also grown on sapphire substrates by laser deposition. In-situ resistivity measurements were employed to study the film formation process during laser deposition. A simple model was given to explain the in-situ resistivity data. Finally, a deposition temperature window was found to produce good quality CdS/YBCO heterostructures. The superconducting transition temperature of the YBCO films was degraded to 68K from an original Tc of 85 K after CdS deposition. The degradation of the superconducting properties was found mainly due to the interactions in the interface region.

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