Bablich, Andreas
8 results
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Publication Access status: Metadata only , 3 - Some of the metrics are blocked by yourconsent settings
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: Open Access , High-speed focus-induced photoresponse in amorphous silicon photodetectors for optical distance measurementsThe Focus-Induced Photoresponse (FIP) enables 3D sensing capabilities by evaluating the irradiance dependent non-linear detector response in defect-based materials. Since this advantage is intricately associated to a slow response, the electrical bandwidth of previous FIP sensors is limited to a few kHz only. We report the FIP in amorphous silicon pin photodiodes and propose a sensor read out based on a harmonics analyses. We achieve modulation frequencies of 500 kHz and a non-linear beat frequency detection up to at least 3.5 MHz, surpassing the bandwidth of state-of-the-art architectures by at least a factor of 175. The FIP sensors further achieve signal-to-noise ratios of ∼50 dB, depth resolutions of at least 5.4 mm at 126 cm and a DC FIP detection limit of 1.3 μW/mm2.Source Type:Article318 73 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , High-speed nonlinear focus-induced photoresponse in amorphous silicon photodetectors for ultrasensitive 3D imaging applicationsA large and growing number of applications benefit from simple, fast and highly sensitive 3D imaging sensors. The Focus-Induced Photoresponse (FIP) can achieve 3D sensing functionalities by simply evaluating the irradiance dependent nonlinear sensor response in defect-based materials. Since this advantage is intricately associated to a slow response, the electrical bandwidth of present FIP detectors is limited to a few kHz only. The devices presented in this work enable modulation frequencies of 700 kHz and beat frequency detection up to at least 3.8 MHz, surpassing the bandwidth of reported device architectures by more than two orders of magnitude. The sensors achieve a SNR of at least ∼53dB at 115cm and a DC FIP detection limit of 0.6 µW/mm2. The mature and scalable low-temperature a-Si:H process technology allows operating the device under ambient air conditions waiving additional back-end passivation, geometrical fill factors of 100% and tailoring the FIP towards adjustable 3D sensing applications.Source Type:Article266 242 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Intrinsic photomixing detector based on amorphous silicon for envelope mixing of optical signalsIn this work, a promising device for direct optical envelope mixing, the Intrinsic Photomixing Detector (IPD) based on hydrogenated amorphous silicon, is reported. The IPD directly generates a photocurrent proportional to the nonlinear mixing of two optical modulation envelope functions. Experiments illustrate efficient mixing in the visible range at low light levels down to ϕ1 = 4.36 mW/cm2 (444 nm) and ϕ2 = 1.03 mW/cm2 (636 nm). Modulation frequencies exceeding the MHz range are demonstrated. Electro-optical simulations identify defectinduced electrical field screening within the absorber to cause the nonlinear mixing process, opening-up the opportunity to tailor devices toward application-specific requirements. The IPD functionality paves the way toward very simple but high-performance photodetectors for 3D imaging and ranging for direct optical convolutional sensors or for efficient optical logic gates. Using amorphous silicon provides a photodetector material base, which can easily be integrated on top of silicon electronics, enabling fill factors of up to 100%.Source Type:Article294 185 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Thin-Film Device Development and Technologies - Sensing Principles and Application-Specific Examples(2023)Advanced on-chip integrated photonic and electronic devices, such as hyperspectral photodetectors, depth sensors or memristors, obtain significant drawbacks with respect to performance and/or the technological integration effort. To overcome such limitations, optimized materials and innovative device concepts were developed to maximize performance and integration densities for specific applications. The selected thin and ultra-thin film material examples can obtain significant advantages and exhibit fundamentally different and adjustable material properties compared to their bulk monocrystalline counterparts. Exploiting the benefitial properties of two dimensional (2D) and amorphous semiconducting materials allows the development of high-performance optoelectronic devices, especially for sensing applications. The aim of this work is to demonstrate how novel 2D-material and conventional thin-film semiconductor processing platforms and technologies can be combined to enable a heterogenous device integration on top of chip electronics with enhanced performance. As device examples, 2D-material heterostructure photodetectors for enhanced sensing applications, nonlinear amorphous silicon and graphene photodetectors for depth sensing as well as thin-film memristors for the development of neuro-inspired “smart” cameras are presented, discussed and compared with the state-of-the-art.Source Type:Habilitation1 4
