Search results for "INTERFACE"
showing 10 items of 2139 documents
Two birds with one stone: dual grain-boundary and interface passivation enables >22% efficient inverted methylammonium-free perovskite solar cells
2021
Advancing inverted (p���i���n) perovskite solar cells (PSCs) is key to further enhance the power conversion efficiency (PCE) and stability of flexible and perovskite-based tandem photovoltaics. Yet, the presence of defects at grain boundaries and in particular interfacial recombination at the perovskite/electron transporting layer interface induce severe non-radiative recombination losses, limiting the open-circuit voltage (VOC) and fill factor (FF) of PSCs in this architecture. In this work, we introduce a dual passivation strategy using the long chain alkylammonium salt phenethylammonium chloride (PEACl) both as an additive and for surface treatment to simultaneously passivate the grain b…
A Controllable and Highly Propagative Hybrid Surface Plasmon-Phonon Polariton in a CdZnO-based Two-Interface System
2019
The development of new nanophotonic devices requires the understanding and modulation of the propagating surface plasmon and phonon modes arising in plasmonic and polar dielectric materials, respectively. Here we explore the CdZnO alloy as a plasmonic material, with a tunable plasma frequency and reduced losses compared to pure CdO. By means of attenuated total reflectance, we experimentally observe the hybridization of the surface plasmon polariton (SPP) with the surface phonon polariton (SPhP) in the air-CdZnO-sapphire three-layer system. We show how through the precise control of the CdZnO thickness, the resonance frequencies of the hybrid surface plasmon-phonon polariton (SPPP) are tune…
Optical properties of lithium gallium oxide
2017
Abstract The optical dielectric function tensor of orthorhombic single-crystal LiGaO 2 was determined for polarizations along a , b , and c crystal-axis in the photon energy range from 0.04 eV to 6.5 eV by the generalized spectroscopic ellipsometry. In the far-infrared spectral range from 12.4 meV to 40 meV, the dielectric function was determined from conventional polarized transmittance and polarized reflectance measurements. Lineshape analysis of the dielectric function tensor major components allowed for a determination of the long-wavelength optical phonon characteristics, refractive indices dispersion, and parameters of interband and excitonic optical transitions.
Structure and chemical bonds in reactively sputtered black Ti–C–N–O thin films
2011
The evolution of the nanoscale structure and the chemical bonds formed in Ti–C–N–O films grown by reactive sputtering were studied as a function of the composition of the reactive atmosphere by increasing the partial pressure of an O2+N2 gas mixture from 0 up to 0.4 Pa, while that of acetylene (carbon source) was constant. The amorphisation of the films observed by transmission electron microscopy was confirmed by micro- Raman spectroscopy, but it was not the only effect associated to the increase of the O2+N2 partial pressure. The chemical environment of titanium and carbon, analysed by X-ray photoemission spectroscopy, also changes due to the higher affinity of Ti towards oxygen and nitro…
Enhanced optical response of InSe nanosheet devices decorated with CsPbX3 (X = I, Br) perovskite nanocrystals
2021
Abstract The combination of several two-dimensional materials opens the door for the creation of cooperative nanodevices with functionalities that complement to each other and even compensate the weaknesses of the individual components. Two-dimensional indium selenide (InSe) shows one of the largest tunability bandgap found in two-dimensional materials with application in optoelectronics. However, the intrinsic out-of-plane luminescent dipolar nature limits its implementation in devices operating in vertical configuration. All-inorganic CsPbX3 (X = Br, I) cubic nanoparticles offer high absorption and emission quantum yields and great integrability with two-dimensional materials. Combining t…
X-RAY PHOTOEMISSION ELECTRON MICROSCOPE DETERMINATION OF ORIGINS OF ROOM TEMPERATURE FERROMAGNETISM AND PHOTOLUMINESCENCE IN HIGHCo-CONTENTCoxZn1-xOF…
2014
In this paper, we reported on the X-ray photoemission electron microscope (XPEEM) determination of magnetic and luminescence origins for two CoxZn1-xO films. The cobalt fraction x of radio frequency co-sputtered samples were 0.86(2) and 0.92(2), respectively. Films were ferromagnetic and semiconductive. Unique narrow green color lines beside the ZnO intrinsic emissions were found with a decay time in microsecond range at room temperature. Origins of magnetic and luminescence properties were determined with XPEEM. The X-ray absorption near edge structure at the Co L3-edge denoted that Co was partially oxidized, and phase-contrast images together with chemical composition identification furt…
Properties of ZnO coatings obtained by mechanoactivated oxidation
2009
In this work a new method based on the mechanoactivated oxidation has been applied for obtaining thin nanostructured transparent ZnO coatings on glass. Zn has been transferred onto a glass substrate at room temperature using a quickly rotating steel wire brush. Afterwards by subsequent annealing it is modified into a transparent ZnO coating. The temperature range in which formation of the needle-like (whiskers) structure and transition to the fine-grained structure occurs has been determined. The interrelation between physical properties and the change of microstructure of the ZnO coatings has been shown.
Optical, structural, and morphological characterisation of epitaxial ZnO films grown by pulsed-laser deposition
2013
We report on ZnO epitaxial growth by pulsed-laser deposition (PLD) on different substrates, such as quartz, sapphire, and GaN template. Approximately 1 mu m-thick films were grown under different substrate temperatures and background oxygen conditions. X-ray diffraction analysis indicated preferential growth along the c-axis direction with a full-width at half maximum(FWHM) of the rocking curve as narrow as 230 arcs in the case of the GaN template. Low-temperature photoluminescence showed A-excitonic emission near 3.36 eV and a FWHM of (DXA)-X-0 emission as small as 2.89 meV at 9 K. Atomic force microscope measurements showed that roughness as low as 18 nm could be obtained. These results p…
Synthesis of multi-color luminescent ZnO nanoparticles by ultra-short pulsed laser ablation
2020
Abstract Crystalline ZnO nanoparticles (NPs) are synthesized by ultra-short femtosecond (fs) pulsed laser ablation (PLA) of a zinc plate in deionized water, and are investigated by optical absorption and time resolved luminescence spectra in combination with the morphology and structure analysis. The comparison with previous experiments based on short nanosecond (ns) PLA highlights that pulse duration is a crucial parameter to determine the size and the optical properties of ZnO NPs. While short PLA generates NPs with average size S ‾ of ~ 30 nm, ultrashort PLA allows to achieve much smaller NPs, S ‾ ⩽ 10 nm, that evidence weak quantum confinement effects on both the absorption edge and th…
Photoluminescence of Point Defects in Silicon Dioxide by Femtosecond Laser Exposure
2021
The nature of the radiation-induced point defects in amorphous silica is investigated through online photoluminescence (PL) under high intensity ultrashort laser pulses. Using 1030 nm femtosecond laser pulses with a repetition rate of 1 kHz, it is possible to study the induced color centers through their PL signatures monitored during the laser exposure. Their generation is driven by the nonlinear absorption of the light related to the high pulse peak powers provided by femtosecond laser, allowing to probe the optical properties of the laser exposed region. The experiment is conducted as a function of the laser pulse power in samples with different OH contents. The results highlight the dif…