This paper presents a concept to significantly improve the photocurrent of ultrathin crystalline silicon solar cells using plasmonic hemispherical dielectric-metal (core-shell) nanoparticles and backside gratings. The design of three-dimensional spherical and hemispherical arrays of nanoparticles on top of the surface of 0.8 μm crystalline silicon solar cells was simulated using finite-difference time-domain (FDTD) method. We used the FDTD results to investigate the photocurrent by solving the Poisson and drift diffusion equations. The results indicate an enhancement of between 80% and 93% in the photocurrent for cells with hemispherical Ag and Ag–SiO₂ core-shell nanoparticles, respectively, compared to a cell with spherical nanoparticles. In addition, for obtaining a higher photocurrent, triangular gratings were applied on the back side of the absorber and we obtained a photocurrent of $22\mathrm{mA}/{\mathrm{cm}}^2$. The simulated results indicate that the proposed structures increase the spectral response of thin-film crystalline silicon solar cells over a solar spectrum in the range of 400 nm–1200 nm. Finally, we investigated photocurrent as a function of incidence light angle and concluded that this approach is applicable to various thicknesses and shapes of nanoparticles.

The ongoing quest to find methods to control the trap states in solution processed nanostructures (trap engineering) will revolutionise the applications of nanomaterials for optoelectronic purposes. In this paper, we present a new combined experimental/theoretical approach (molecular orbital theory) allowing a new view on trap engineering of nanostructures for applications in photodetectors. PbSe quantum dots (QDs) of about 30 nm diameter were prepared in a solution-based process from lead iodide (PbI₂) and chloride (PbCl₂), while using lead acetate (PbOAc₂) reliably gave particles of about 200 nm in size under the same conditions. Comparison of the dangling acetate (OAc⁻) versus the spherical monoatomic surface ligands chloride (Cl⁻) and iodide (I⁻) and varying the covalent/ionic character of the particle-surface ligand (ionic: OAc⁻ > Cl⁻ > I⁻: covalent) bond allowed an interesting insight into what governs the trap states. Density functional theory (DFT) calculations are used to study band structures and density of states and show trap states localised within the bandgap moving to the conduction or valence band upon interaction of surface metal atoms with the surface ligands. Infrared detectors based on these materials are fabricated and allowed high-speed mid-infrared photo-detection with 100 ns rise and 110 ns fall response times.

Background: The identification of protein coding regions (exons) in DNA sequences using signal processing techniques is an important component of bioinformatics and biological signal processing. In this paper, a new method is presented for the identification of exonic regions in DNA sequences. This method is based on the cross-correlation technique that can identify periodic regions in DNA sequences. Results: The method reduces the dependency of window length on identification accuracy. The proposed algorithm is applied to different eukaryotic datasets and the output results are compared with those of other established methods. The proposed method increased the accuracy of exon detection by 4% to 41% relative to the most common digital signal processing methods for exon prediction. Conclusions: We demonstrated that periodic signals can be estimated using cross-correlation. In addition, discrete wavelet transform (DWT) can minimise noise while maintaining the signal. The proposed algorithm, which combines cross-correlation and DWT, significantly increases the accuracy of exonic region identification.

In this study, p-Phenylenediaminium iodide (PDAI) is used to in-situ growth of 2D (PDA)₂PbI₄ perovskite layer between (FAPbI₃)_0.85(MAPbBr₃)_0.15 3D perovskite and CuSCN as a cheap hole transport layer. The results indicate that the incorporation of 5 mg mL⁻¹ PDAI leads to enlarged grain sizes, compact grain boundaries, reduced trap density, efficient charge extraction, and enhanced stability of perovskite film. Passivation of perovskite film with the appropriate amount of PDAI helps in achieving efficient perovskite solar cell with a PCE as high as 16.10%, a J_SC of 21.45 mA cm⁻², a V_OC of 1.09 V, and FF of 70.21%, with negligible hysteresis and excellent moisture stability which remains 99.01% of its initial PCE value after 5 h in high relative humidity of 90 ± 5% and shows unchanged PCE after 1440 h in low relative humidity of 15 ± 5%. Most strikingly, this ultra-thin 2D passivation layer by the use of PDA cations as a bulky spacer not only passivates the defects on the surface of perovskite film but also induces self-healing properties in PSCs which can be rapidly recovered after keeping away from water vapor exposure. This study introduces the cheap and extra stable perovskite solar cells with outstanding self-healing ability towards commercialization.

Infrared (IR) cameras based on semiconductors grown by epitaxial methods face two main challenges, which are cost and operating at room temperature. The alternative new technologies which can tackle these two difficulties develop new and facile material and methods. Moreover, the implementation of high speed camera, which makes high resolution images with normal methods, is very expensive. In this paper, a new nanostructure based on a cost-effective solution processed technology for the implementation of the high-speed mid-infrared light camera at room temperature is proposed. To this end, the chemically synthesized PbSe–PbI₂ core–shell Quantum Dots (QDs) are used. In this work, a camera including 10 × 10 pixels is fabricated and synthesized QDs spin-coated on interdigitated contact (IDC) and then the fabricated system passivated by epoxy resin. Finally, using an electronic reading circuit, all pixels are converted to an image on the monitor. To model the fabricated camera, we solved Schrodinger–Poisson equations self consistently. Then output current from each pixel is modeled based on semiconductor physics and dark and photocurrent, as well as Responsivity and Detectivity, are calculated. Then the fabricated device is examined, and dark and photocurrents are measured and compared to the theoretical results. The obtained results indicate that the obtained theoretical and measured experimental results are in good agreement together. The fabricated detector is high speed with a rise time of 100 ns. With this speed, we can get 10 million frames per second; this means we can get very high-resolution images. The speed of operation is examined experimentally using a chopper that modulates input light with 50, 100, 250, and 500 Hz. It is shown that the fabricated device operates well in these situations, and it is not limited by the speed of detector. Finally, for the demonstration of the proposed device operation, some pictures and movies taken by the camera are attached and inserted in the paper.