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An efficient room-temperature self-powered, broadband (300 ​nm–1100 nm) photodetector based on a CuO–TiO2/TiO2/p-Si(100) heterostructure is demonstrated. The CuO–TiO2 nanocomposites were grown in a two-zone horizontal tube furnace on a 40 ​nm TiO2 thin film deposited on a p-type Si(100) substrate. The CuO–TiO2/TiO2/p-Si(100) devices exhibited excellent rectification characteristics under dark and individual photo-illumination conditions. The devices showed remarkable photo-response under broadband (300–1100 ​nm) light illumination at zero bias voltage, indicating the achievement of highly sensitive self-powered photodetectors at visible and near-infrared light illuminations. The maximum response of the devices is observed at 300 ​nm for an illumination power of 10 ​W. The response and recovery times were calculated as 86 ​ms and 78 ​ms, respectively. Moreover, under a small bias, the devices showed a prompt binary response by altering the current from positive to negative under illumination conditions. The main reason behind this binary response is the low turn-on voltage and photovoltaic characteristics of the devices. Under illumination conditions, the generation of photocurrent is due to the separation of photogenerated electron-hole pairs within the built-in electric field at the CuO–TiO2/TiO2 interface. These characteristics make the CuO–TiO2/TiO2 broadband photodetectors suitable for applications that require high response speeds and self-sufficient functionality.

In the present work, we report the effect and improvement of PVC polymer blend nanocomposites performance with addition of lanthanum oxide (La2O3) nanofiller. The structural properties of the samples were studied using different characterization techniques such as XRD, FTIR, Ramman and SEM. The X-ray diffraction peaks of La2O3 are with agreement with the pure hexagonal phase. The La2O3 sample was found to have crystallites size with an average about 15 nm. XRD, FTIR and SEM analysis confirmed the interaction of PVC/La2O3 polymer nanocomposites. The obtained band gaps of PVC/La2O3 polymer nanocomposites decreased (5.72 – 5.0 eV) upon increasing the nanofiller content. The obtained values of single oscillator energy (E0) showed a decrease (5.88 – 3.28 eV) while dispersion energy (Ed) increases (5.64 – 7.20 eV) upon increasing the concentration of La2O3. The estimated values of static refractive index (n0) showed an increase (1.40 – 1.79) upon increasing the percentage of La2O3. Moreover, the nonlinear refractive index (n2) value was changed from 1.56 10−13 to 33.56 x 10−13 esu. Finally, the addition of La2O3 nanofillers increase the polarizability of the polymer molecules and hence the nonlinear refractive index.

A mid-wavelength p–B–i–n infrared photodetector constituting ternary alloys of an InAs0.9Sb0.1 absorber and an AlAs0.05Sb0.95 electron barrier was demonstrated to operate at room temperature. The results of high-resolution x-ray diffraction (XRD) analysis indicate the high crystalline quality of the barriode detector structure, grown via molecular beam epitaxy, as supported by the strong XRD peak intensity of InAsSb and its corresponding defect density as low as ∼2.0 × 108 cm−2. The dark current of the barriode detector remained diffusion-limited in the 280–300 K temperature range, and generation–recombination became dominant at 220–260 K owing to the deep-level traps in the depletion region of the absorber and near the lattice-mismatched heterointerface of AlAsSb/InAsSb. Two distinct shallow traps in the InAsSb absorber were identified through Laplace deep-level transient spectroscopy with the activation energies of Et1 = 20 meV and Et2 = 46 meV. The Et1 trap is associated with the hole localization states induced by the alloy disorder of InAsSb, whereas the Et2 trap originated from a point defect of In vacancies in InAsSb. At 300 K, the barriode detector exhibited a 90% cutoff wavelength of 5.0 μm, a peak current responsivity of 0.02 A/W, and a dark current density of 1.9 × 10−3 A/cm2 under a bias voltage of −0.3 V, providing a high specific detectivity of 8.2 × 108 cm Hz1/2/W.

The present study describes the optical properties for prepared polymer nanocomposites of PVDF at different content of MoO3/g-C3N4. The structural properties of polymer films were analysed via XRD, FTIR and ESEM techniques. The XRD diffraction patterns of PVDF with different concentrations of MoO3/g-C3N4 have two characteristic peaks at 2 θ = 18.4° and 20.3° where first peak was assigned to α-phase, while last peak was attributed to β-phase. The ESEM micrographs of PVDF-MoO3/g-C3N4 nanocomposites have shown smooth surface topography. According to the UV–visible absorption spectra, the UV absorption of PVDF was increased when adding MoO3/g-C3N4 nanoparticles where distinct peak was appeared in the UV region at 310 nm and its edges become more intense and moved towards higher wavelength after MoO3/g-C3N4 incorporation. The optical values of (Edir) and (Eind) energies have decreased with increasing the nanoparticle composites content. The optical band gap energy (Eopt) was decreasing from 5.66 eV to 4.56 eV as increasing the content of MoO3/g-C3N4. The refractive index (n) was increased with increasing the concentration of MoO3/g-C3N4 in nanocomposites samples, except for the sample with 0.25 wt%. The distinctive optical characteristics of PVDF-MoO3/g-C3N4 qualify such polymer nanocomposites for optoelectronic applications.

In this work, a synthesis technique for highly homogeneous PVDF-CaFe2O4 polymer films direct from solution was developed. The structural characterizations were conducted using XRD, FTIR, and ESEM experimental techniques. The XRD characteristic peaks of CaFe2O4 nanoparticles revealed a polycrystalline structure. The average crystallite size for CaFe2O4 was calculated to be 17.0 nm. ESEM micrographs of PVDF nanocomposites containing 0.0, 0.25, 0.75, and 1.0 wt% of CaFe2O4 showed smooth surface topography. The direct Edir and indirect Eind band gap energies for the PVDF-CaFe2O4 nanocomposites were decreased with the additions of 0.0–1.0 wt% CaFe2O4. In addition, the refractive index (n0) increased from 3.38 to 10.36, and energy gaps (Eg) decreased from 5.50 to 4.95 eV. The nonlinear refractive index (n2) for the PVDF-CaFe2O4 nanocomposites was improved with the addition of CaFe2O4 nanoparticles, exceeding those reported in the literature for PVC, PVA, and PMMA nanocomposites. Therefore, the PVDF-CaFe2O4 nanocomposites are expected to take the lead in optoelectronic applications because of their unusual optical properties.