Vehicular Visible Light Communications

Vehicular communications are foreseen to play a key role to increase road safety and realize autonomous driving. In addition to the radio frequency (RF)-based dedicated short range communication (DSRC) and long-term evolution (LTE) communication technologies, vehicular visible light communication (V2LC) is proposed as a complementary solution, utilizing readily deployed vehicle light emitting diode (LED) lights as transmitter with image sensors such as photodetector (PD) and camera as the receivers. V2LC fundamentals including transmitter and receiver characteristics with dimming capabilities are reviewed in this chapter. Depending on the field measurements using off-the-shelf automotive LED light, communication constraints are demonstrated. Moreover, considering the line-of-sight (LoS) characteristics, security aspects of V2LC is compared with the DSRC for a practical vehicle-to-vehicle (V2V) communication scenario. Finally, superiority of V2LC in terms of communication security with the proposed SecVLC method is demonstrated through simulation results

DR-70: A promising biomarker for the detection of lung cancer

Objective: Lung cancer (LC) is characterized by an aggressive phenotype with a high mortality rate, early metastasis, and proliferation rate. Treatment options and prognosis differ significantly at each stage. Despite the availability of multiple imaging studies and invasive procedures, the disorder is diagnosed at an advanced stage. Therefore, it is essential to find biomarkers for the early detection of LC. Patients and Methods: Between 2018 and 2020, 73 LC and 71 control with the same demographic characteristics were included in our study. DR-70 level was measured by a photometric method in serum samples taken from all subjects. Results: A total of 144 subjects (110 male, 34 female) was included in the study. DR-70 levels in the LC group (2.53 +/- 2.64 mu g/mL) were found to be statistically significantly higher than the control group (0.56 +/- 1.23 mu g/mL). Clinical sensitivity and specificity of DR-70 for LC were found to be 87.67% and 88.73%. Conclusions: The high sensitivity and specificity of DR-70 can be used as a biomarker for rapid diagnosis in patients with LC. Compared with other tumor biomarkers, DR-70 seems to have a better sensitivity and specificity in the diagnosis of LC

Photoluminescence spectroscopy in the study of growth of CdSxSe1-x nanocrystals in glass

Growth of CdS0.08Se0.92 nanocrystals embedded in glass is studied through the combinative analysis of optical absorption and photoluminescence (PL) spectroscopy at room temperature. The quantum confinement effect is observed in these structures. Average nanocrystal radii are found to be in the range of 2.3-4.2 nm with the help of a quantized state effective mass theory. Photoluminescence spectra are studied by means of the model of Ravindran et al (1999 Nanostruct. Mater. 11 603). The difference between the energies of the deep trap peak and first exciton peak is found to be similar to0.2-0.3 eV. The possible sources of the overall shift in these peaks are also discussed

Temperature- and excitation intensity-dependent photoluminescence in Ga4Se3S layered crystals

Photoluminescence (PL) spectra of Ga4Se3S layered single crystals have been studied in the wavelength region of 535-855 nm and in the temperature range of 16-200 K. Two PL bands centered at 572 nm (2.168 eV, A-band) and 652 nm (1.902 eV, B-band) were observed at T = 16 K. Variations of both bands have been studied as a function of excitation laser intensity in the range 0.10-149.92 mW cm(-2). The A-band is attributed to radiative transition from donor level located 0.125 eV below the bottom of conduction band to shallow acceptor level located 0.011 eV above the top of the valence band. The increase of the width of B-band and its quenching with increasing temperature is explained using the configurational coordinate model

Optical anisotropy in GaSe

Optical anisotropy of the layer semiconductor GaSe has been studied by photoluminescence (PL) and Fourier Transform Infrared Spectroscopy (FTIR). The PL spectra are dominated by two closely positioned emission bands resulting from the free exciton and the bound exciton connected direct band edge of GaSe. Photoluminescence and transmission spectra of GaSe crystals have been measured for two cases in which the propagation vector k is perpendicular (k⊥c) and parallel to the c-axis (k//c). Peak position of the PL emission band and the onset of the transmission have been found to be significantly different for these two cases. This observed anisotropy is related to anisotropic band structure and the selection rules for the optical absorption in layered GaSe. FTIR transmission spectrum is in good agreement with PL results. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Integration of graphene with GZO as TCO layer and its impact on solar cell performance

In this study, we investigated the impact of incorporating graphene with Ga-doped ZnO (GZO) when employing them as a TCO layer on Si-based solar cell. GZO thin films with various thicknesses (50-450 nm) were fabricated by the sputtering method using a single target. The aim here was to determine the GZO film with the optimum thickness to incorporate it with single layer graphene as TCO. This thickness was found to be 350 nm as that was the best crystalline quality found in the Opattern. Further, this sample had the lowest sheet resistance and highest transmission values as confirmed by electrical (sheet resistance), and optical characterizations (transmission). Topographic (SEM and AFM), electrical (resistivity and carrier concentration) measurements were also conducted on the same sample. The graphene film grown on copper in a CVD system was then transferred on top of this sample to fabricate the hybrid TCO structure. We found that graphene integrated GZO hybrid TCO film showed higher sheet resistance due to high sheet resistance of graphene and similar optical properties thanks to high optical transmission of graphene. Employing graphene-based TCO layer in the solar cell resulted in higher open-circuit voltage, consequently improving the conversion efficiency from 10.0% to 11.2%. (c) 2021 Elsevier Ltd. All rights reserved