Tuning the intrinsic structural and stoichiometric properties by different means is used for increasing the green energy production efficiency of complex oxide materials. Here, we report on the formation of self-assembled nanodomains and their effects on the photoelectrochemical (PEC) properties of LaFeO₃ (LFO) epitaxial thin films as a function of layer’s thickness. The variation with the film’s thickness of the structural parameters such as in-plane and out-of-plane crystalline coherence length and the coexistence of different epitaxial orientation—SrTiO₃// LFO, SrTiO₃// LFO and [110] LFO//[10] STO, as well as the appearance of self-assembled nanodomains for film’s thicknesses higher than 14 nm, is presented. LFO thin films exhibit different epitaxial orientations depending on their thickness, and the appearance of self-assembled nanopyramids-like domains after a thickness threshold value has proven to have a detrimental effect on the PEC functional properties. Using Nb:SrTiO₃ as conductive substrate and 0.5 M NaOH aqueous solution for PEC measurements, the dependence of the photocurrent density and the onset potential vs. RHE on the structural and stoichiometric features exhibited by the LFO photoelectrodes are unveiled by the X-ray diffraction, high-resolution transmission electron microscopy, ellipsometry, and Rutherford backscattering spectroscopy results. The potentiodynamic PEC analysis has revealed the highest photocurrent density J_photocurrent values (up to 1.2 mA/cm²) with excellent stability over time, for the thinnest LFO/Nb:SrTiO₃ sample, both cathodic and anodic behavior being noticed. Noticeably, the LFO thin film shows unbiased hydrogen evolution from water, as determined by gas chromatography in aqueous 0.5 M NaOH solution under constant illumination.

Introduction: This paper deals with the class of versatile semiconducting materials called perovskites, which have been deposited for the first time on flexible substrates and then tested for radiation detection monitoring applications.Methods: Lead halide inorganic perovskite, CsPbCl₃, 0.4–1 μm-thick films have been grown on plastic flexible substrates equipped with interdigitated electrodes (IDEs) by magnetron sputtering at room temperature.Results: First measurements in realtime configuration are reported for a 1–µm thick prototype under proton beams with energy in the range 100–228 MeV and 1–10 nA extraction currents, of interest for protontherapy applications.Discussion: Experimental results evidence good performances of our sample as a real-time monitoring device. Current stability under UV and proton beam exposure has been tested in the range 0.1–120 s, as well as reproducibility under multiple exposures. The measured current signal proved to be linearly dependent on the extraction currents at a given proton energy. Linearity of the current signal of the device with proton fluxes was also proved within two order of magnitude range, about 10⁷–10⁹ p/s. These promising results, when coupled with easyness of fabrication, low processing costs and high versatility of electrode configurations, all features characterizing the manufacturing process, put into evidence lead halide perovskites as promising candidates for real-time radiation detection in protontherapy.

The response of resistive In₂O_3−x sensing devices was investigated as a function of the NO₂ concentration in different operative conditions. Sensing layers are 150 nm thick films manufactured by oxygen-free room temperature magnetron sputtering deposition. This technique allows for a facile and fast manufacturing process, at same time providing advantages in terms of gas sensing performances. The oxygen deficiency during growth provides high densities of oxygen vacancies, both on the surface, where they are favoring NO₂ absorption reactions, and in the bulk, where they act as donors. This n-type doping allows for conveniently lowering the thin film resistivity, thus avoiding the sophisticated electronic readout required in the case of very high resistance sensing layers. The semiconductor layer was characterized in terms of morphology, composition and electronic properties. The sensor baseline resistance is in the order of kilohms and exhibits remarkable performances with respect to gas sensitivity. The sensor response to NO₂ was studied experimentally both in oxygen-rich and oxygen-free atmospheres for different NO₂ concentrations and working temperatures. Experimental tests revealed a response of 32%/ppm at 10 ppm NO₂ and response times of approximately 2 min at an optimal working temperature of 200 °C. The obtained performance is in line with the requirements of a realistic application scenario, such as in plant condition monitoring.

In this paper we report the development of thin films composed of two piezoelectric materials, namely (Ba(Ti_0.8Zr_0.2)O₃-x(Ba_0.7Ca_0.3)TiO₃ (BCTZ) and polyvinylidene difluoride (PVDF), thus obtaining high piezoelectric hybrid heterostructures for making them a viable option for wearable pressure sensors. The piezoelectric output response as a function of different weight percentage of BCTZ ceramic powders (x = 0.50 BCTZ50 and x = 0.55 BCTZ55) in the PVDF matrix was investigated. The highest value of the piezoelectric coefficient d33 and the capacitance, with low dielectric loss was obtained for the heterostructure composed of PVDF/BCTZ50.

We present an experimental study concerning the interplay between amplified spontaneous emission (ASE) and photoluminescence in polycrystalline thin films (100–300 nm) realized by Radio-Frequency Magnetron Sputtering (RF-MS) without the use of a waveguide configuration. Our results show that the amplification of the spontaneous emission requires only a thickness comparable to the absorption length (≈100 nm). Moreover, the strong ASE signal measured at room temperature shows a peculiar behavior performing a z-scan of the exciting beam waist: increasing the fluence, the decrease of the ASE intensity is accompanied by a significant decrease of the absorption coefficient, indicating the onset of a non-linear process due to multiexciton population (space filling effect) in the film nanocrystallites. Our studies performed with high spectral resolution reveal a modal structure with a significant stability in time, both in the spectral line shape and intensity, from pulse to pulse and demonstrate that CsPbBr3 nanometric films deposited by RF-MS can be efficiently used as active material for coherent light amplification. Moreover, the absorption change detected at high photon fluence can be used for the development of light modulators.

In this study we report the specific interaction of various gases on the modified surface of acoustic wave devices for gas sensor applications, using the piezoelectric ceramic material BaSrTiO₃ (BST), with different concentrations of Sr. For enhancing the sensitivity of the sensor, the conductive polymer polyethylenimine (PEI) was deposited on top of BST thin films. Thin films of BST were deposited by pulsed laser deposition (PLD) technique and integrated into a test heterostructure with PEI thin films deposited by matrix assisted pulsed laser evaporation (MAPLE) and interdigital Au electrodes (IDT). Further on, the layered heterostructures were incorporated into surface acoustic wave (SAW) devices, in order to measure the frequency response to various gases (N₂, CO₂ and O₂). The frequency responses of the sensors based on thin films of the piezoelectric material deposited at different pressures were compared with layered structures of PEI/BST, in order to observe differences in the frequency shifts between sensors. The SAW tests performed at room temperature revealed different results based on deposition condition (pressure of oxygen and the percent of strontium in BatiO₃ structure). Frequency shift responses were obtained for all the tested sensors in the case of a concentration of Sr x = 0.75, for all the analysed gases. The best frequency shifts among all sensors studied was obtained in the case of BST50 polymer sensor for CO₂ detection.