Search

Abstract: Cubic Mg x Zn1−x O thin films were deposited on amorphous silicon dioxide substrate by reactive electron beam evaporation (REBE) at low temperature (250°C). The characterizations of crystalline structure and morphology of the ternary films demonstrated that the cubic Mg x Zn1−x O films are of highly (001) orientation and have uniform surface. The cubic Mg0.83Zn0.17O film deposited on quartz demonstrates wide band gap (6.45eV) and has very high transparency (>95%) in broad wavelength range from ultraviolet (0.3μm) to mid-infrared light (5.5μm). The refractive indices for the cubic Mg x Zn1−x O decrease as Mg fraction increases. The characters of low optical absorption in broad wavelength range and feasibility of changing refractive index by Mg fraction variation in the ternary Mg x Zn1−x O films could render potential applications in integrated optical devices. [Copyright &y& Elsevier]

• Dodecylammonium chloride assisted the formation of compact lead-free perovskites films. • The crystallinity and stoichiometric defects of the films are significantly improved. • Enhanced optical absorption, photoluminescence, and extended carrier lifetime is achieved. • Solar cell device exhibited a highest PCE for the solution-processed Cs 3 Bi 2 I 9 -based devices. • Photovoltaic device demonstrated an enhanced environmental stability in the ambient air. Bismuth is considered as one of the most promising candidates to replace Pb in the organo-lead halide perovskite, a classical material for various optoelectronic applications. When utilized in a photovoltaic cell, the performance of the cell drops due to deterioration in the absorber film and the changes in its crystal structures. In this work, a small amount of dodecylammonium chloride, C 12 H 25 NH 3 Cl (DCl) is added into Cs 3 Bi 2 I 9 (CBI), resulting in a pinhole-free high-quality perovskite (PVK) film via a single-step solution processability, also confirmed by FTIR and XPS analyses. Structural, optical, and microscopic analyses showed that the quality, surface features, and crystallinity of the CBI films are significantly improved by adding DCl. The prepared films are successfully demonstrated in a solar cell and exhibited considerably improved photovoltaic (PV) characteristics (V OC by ~47%, J SC by ~33%, FF by 13%, and PCE by 115%) over pure CBI-based devices. Moreover, the PV device retained more than 95% of its initial PCE in the ambient laboratory environment (relative humidity 55±5%). To the best of our knowledge, this is the highest PCE along with extended environmental stability reported for solution processed CBI-based perovskite solar cells. [ABSTRACT FROM AUTHOR]

• Ambient environment synthesis of the hybrid perovskites films and solar cells. • Addition of Dodecylammonium for the 1st time into the triple cation perovskites. • HPVKs thin films showed stablility for 50 days in relative humidity well above 50%. • HPVKs thin films showed stablility to high thermal stress of 85 ℃ for 24 h. • Solar-cell made of HPVKs yielded a PCE of 5%. • PCE of the solar cell retained up to 64% for 9 days in RH > 50% and 85 ℃. Owing to their high efficiency and extended environmental stability, hybrid 2D/3D-perovskites (HPVKs) are gaining an increasing interest in the field of organometal halide perovskite solar cells (PSCs). In HPVKs, the 3D component acts as an active material, where its 2D-counterpart provides protection against environmental factors. Here in, we add dodecylammonium-chloride (DACl) into the precursor solution of 3D-perovskites (FAMAPbI 3) to achieve HPVKs. The formation of HPVK is confirmed by XRD, optical absorption, and Fourier-transform infrared (FTIR) spectroscopies. The structural and optical analysis affirmed that in the case of HPVKs, not only the crystallinity of perovskites is improved significantly but also a variation in its structural properties and optical bandgap have occurred. It is also observed that the surface morphologies of HPVK films are considerably improved with the incorporation of DACl. A minute amount of CsI is also added into the precursor solution of HPVKs, which further assist the formation of HPVKs and consequently causes a significant increase in the carrier lifetime. Finally, a solar cell made of HPVKs shows an improved PCE than pure 3D-perovskites. All HPVKs films and solar-cells are prepared in the ambient humidity and found to be more hydrophobic and stable, not only under relative humidity >50% but also under high thermal stress of 85 ℃. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dodecylammonium chloride as an additive helps in the ambient fabrication of perovskite films. • Low-temperature hot-casting is realized in the preparation of perovskite films in an ambient environment. • Perovskite films exhibited better crystallinity and bigger grains (<110 µm) • Low-voltage operational ReRAM devices with a high ON/OFF ratio are realized. Fabricating perovskite (PVK) films with large grains and compact grain boundaries via solution processability is demanding for efficient electronic and optoelectronic devices. Hot-casting produces dense PVK films with bigger and adjacent grains; however, involves higher temperatures and an inert atmosphere that increases the fabrication cost. Herein, using dodecylammonium chloride (DCl) as an additive, combined with hot-casting is utilized and compact bi-cation PVK films with grain size > 110 µm are synthesized at lower temperature and ambient air. It is revealed that the films have a dense microstructure with no voids among the grains. Also, the films are highly crystalline with preferentially orientated crystals and showed greater hydrophobicity and an extended carrier lifetime. Finally, the films are employed in a resistive-memory storage device, which demonstrated a high ON/OFF ratio of > 106 and lower power consumption. Such high-quality films prepared at ambient conditions could be useful for the realization of other highly efficient optoelectronic devices. [ABSTRACT FROM AUTHOR]

Oxide p-type transistors are expected in realization of complementary circuits. Here, amorphous p-type NiO thin films were deposited on glass substrates by radio frequency (rf) sputtering at various growth temperatures and O 2 /Ar flow ratios. The influence of growth temperature and O 2 /Ar flow ratio on the structural and electrical properties of amorphous NiO thin films has been systematically investigated by means of characterizations from X-ray diffraction, UV–vis spectroscopy, and electrical measurements. Pure Ar ambient with room temperature (RT) growth of NiO films shows the highest mobility of 1.07 cm 2 /Vs, and hole concentration of 2.78 × 10 17 cm − 3 . Initial p-type NiO-based thin film transistors grown by magnetron sputtering demonstrated a mobility of 0.05 cm 2 /Vs, a threshold voltage (Vth) of − 8.6 V, subthreshold swing (S) of 2.6 V/dec, the current on–off ratio of 10 3 , respectively. [ABSTRACT FROM AUTHOR]

Abstract: Regular shape defects on the surface of PbTe thin films grown by molecular beam epitaxy (MBE) were studied by scanning electron microscope (SEM). Two types of regular shape defects were observed on Te-rich PbTe films grown at substrate temperature T ≥235°C with a beam flux ratio of Te to PbTe (R f) to be 0.5 and at 280°C with a R f ≥0.4, which include cuboids and triangular pyramids. The formation mechanism of the observed regular shape defects is interpreted as following: They are the outcome of fast growth rate along {100} crystal planes that have the lowest surface energy and the enclosure of the {100} crystal planes. The formation of the regular shape defects in the growth of PbTe needs appropriate substrate temperature and Te-rich ambience. However, when R f is decreased low enough to make the films slightly Pb-rich, triangular pits that originate from the insufficient glide of the threading dislocations along the main 〈110〉 {100} glide system of PbTe in Cottrell atmosphere, will be the main feature on the film surface. [Copyright &y& Elsevier]