Bolívar, P. Haring
Preferred name
Bolívar, P. Haring
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Publication Access status: Metadata only , Dye-sensitized solar cell: Effect of light on N3 dye/BMII electrolyte based architectureThis study evaluates the photovoltaic performance of Dye-Sensitized Solar Cells (DSSCs) for varied light conditions. The focus of this work is on exploring the experimental characteristics of a thin-film solar cell composed of ITO/TiO2/N3 Dye and BMII electrolyte molecules/Pt/ITO. A meticulous investigation is conducted to understand the impact of different illumination intensities on the efficiency of these solar cells. In the experiments, the power conversion efficiencies (PCE) of the device reached 7.61 % with a maximum open-circuit voltage (Voc) of 0.67 V under 100 mW/cm2 AM 1.5 solar irradiance. The morphology of the TiO2 nanopArticles that have been synthesized for the DSSC were analyzed by Ultraviolet-visible Spectrometry, X-Ray Diffractometry, as well as Scanning Electron Microscopy and Atomic Force Microscopy investigations. Electrochemical impedance spectroscopy (EIS) parameters and Nyquist plot showed that charge transfer and DSSC are important for the equivalent circuit structure. The results of this study allow optimizing the performance of future DSSCs for sustainable energy systems.Source Type:Article4 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Graphene-Based Optoelectronic Mixer Device for Time-of-Flight Distance Measurements for Enhanced 3D Imaging ApplicationsA large and growing number of applications benefit from innovative and powerful 3D image sensors. Graphene photodetectors can achieve 3D sensing functionalities by intrinsic optoelectronic frequency mixing due to the nonlinear output characteristics of the sensor. In first proof of principle distance measurement demonstrations, we achieve modulation frequencies of 3.1 MHz, signal-to-noise ratios of ∼40 dB, distance detection up to at least 1 m, and a mean accuracy of 25.6 mm. The scalable More than Moore detector approach enables geometrical fill factors close to 100% and can easily complement powerful functionalities by simple back-end integration on top of CMOS electronics.Source Type:Article - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , High Responsivity and Ultra-Low Detection Limits in Nonlinear a-Si:H p-i-n Photodiodes Enabled by PhotogatingPhotodetectors operating at the wavelength in the visible spectrum are key components in high-performance optoelectronic systems. In this work, massive nonlinearities in amorphous silicon p-i-n photodiodes enabled by the photogating are presented, resulting in responsivities up to 744 mA/W at blue wavelengths. The detectors exhibit significant responsivity gains at optical modulation frequencies exceeding MHz and a more than 60-fold enhanced spectral response compared to the non-gated state. The detection limits down to 10.4 nW/mm 2 and mean signal-to-noise ratio enhancements of 8.5 dB are demonstrated by illuminating the sensor with an additional 6.6 µW/mm 2 red wavelength. Electro-optical simulations verify photocarrier modulation due to defect-induced field screening to be the origin of such high responsivity gains. The experimental results validate the theory and enable the development of commercially viable and complementary metal oxide semiconductor (CMOS) compatible high responsivity photodetectors operating in the visible range for low-light level imaging and detection.Source Type:Article6 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Interdigitated terahertz metamaterial sensors: design with the dielectric perturbation theory(2024); ; ; ; Designing terahertz sensors for highly sensitive detection of nanoscale thin films and a few biomolecules poses a substantial challenge but is crucial for unlocking their full potential in scientific research and advanced applications. This work presents a strategy for optimizing metamaterial sensors in detecting small quantities of dielectric materials. The amount of frequency shift depends on intrinsic properties (electric field distribution, Q -factor, and mode volume) of the bare cavity as well as the overlap volume of its high-electric-field zone(s) and the analyte. Guided by the simplified dielectric perturbation theory, interdigitated electric split-ring resonators (ID-eSRRs) are devised to significantly enhance the detection sensitivity compared with eSRRs without interdigitated fingers. ID-eSRR’s fingers redistribute the electric field, creating strongly localized enhancements, which boost analyte interaction. The periodic change of the inherent antiphase electric field reduces radiation loss, leading to a higher Q -factor. Experiments with ID-eSRR sensors operating at around 300 GHz demonstrate a remarkable 33.5 GHz frequency shift upon depositing a 150 nm SiO 2 layer as an analyte simulant, with a figure of merit improvement of over 50 times compared with structures without interdigitated fingers. This rational design offers a promising avenue for highly sensitive detection of thin films and trace biomolecules.Source Type:Article5