Browsing by Subject "Photovoltaic"

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    Dual- luminophore efficient luminescent solar concentrator fabricated by low-cost 3D printing
    (Institute of Physics Publishing Ltd., 2022-12-23) Ebrahimisadr, S.; Olyaeefar, Babak.; Ahmadi-kandjani, S.
    Luminescent Solar Concentrators (LSCs), as cost-effective optical devices for photon concentration, have been showing promising applications in photovoltaic systems. Recently, LSCs are being fabricated through different methods to improve their performance and reduce the cost of fabrication. One of the most common and traditional methods of LSC fabrication is Free Radical Polymerization. In which free radicals are formed through thermal decomposition or photolysis of radical initiators. This research work introduces 3D printed LSCs based on CsPbBr3/Cs4PbBr6 Perovskite Nanocrystals (NCs) and an organic Rhodamine b luminophore mixtures. Nowadays, 3D printing technology has a wide variety of applications in industry, medicine, education, etc. 3D printing technique due to the cheap and accessible raw materials is proved to be a facile and cost-effective method to fabricate LSCs. CsPbBr3/Cs4PbBr6 Perovskites were synthesized using a modified reverse microemulsion method. Poly Lactic Acid (PLA) granules with a luminophore concentration of 0.001 wt% were used to fabricate 3D Printer filament as a polymer for LSC fabrication. XRD, FE-SEM, and EDS analysis were applied to synthesized Perovskites to prove formation of CsPbBr3/Cs4PbBr6 Perovskites. Absorption and Photoluminescence spectrum of used luminophores in LSCs were investigated. Re-absorption effect and I–V plots of prepared LSCs were studied. The I–V plot of the attached solar cell to pristine PLA and luminophore dispersed LSCs shows that the solar cell attached to the dual-luminophore LSC is approximately 122% more efficient than the one attached to pristine PLA LSC.
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    ItemOpen Access
    Enhanced Performance of Nanowire-Based All-TiO2 Solar Cells using Subnanometer-Thick Atomic Layer Deposited ZnO Embedded Layer
    (Pergamon Press, 2015) Ghobadi, A.; Yavuz, H. I.; Ulusoy, T. G.; Icli, K. C.; Ozenbas, M.; Okyay, Ali Kemal
    In this paper, the effect of angstrom-thick atomic layer deposited (ALD) ZnO embedded layer on photovoltaic (PV) performance of Nanowire-Based All-TiO2 solar cells has been systematically investigated. Our results indicate that by varying the thickness of ZnO layer the efficiency of the solar cell can be significantly changed. It is shown that the efficiency has its maximum for optimal thickness of 1 ALD cycle in which this ultrathin ZnO layer improves device performance through passivation of surface traps without hampering injection efficiency of photogenerated electrons. The mechanisms contributing to this unprecedented change in PV performance of the cell have been scrutinized and discussed.
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    ItemOpen Access
    MIMIM photodetectors using plasmonically enhanced MIM absorbers
    (SPIE, 2017) Dereshgi, S. Abedini; Okyay, Ali Kemal
    We demonstrate super absorbing metal-insulator-metal (MIM) stacks and MIMIM photosensitive devices operating at visible and near-infrared (VIS-NIR) spectrum, where absorbing (top) MIM and photocollecting (bottom) MIM can be optimized separately. We investigate different bottom metals in absorbing MIM with nanoparticles realized by dewetting of silver thin film on top. While gold and silver have conventionally been considered the most appropriate plasmonic absorbers, we demonstrate different absorbing metals like aluminum and specifically chromium, with its plasma frequency happening at 850 nm, as more efficient layers for absorption. Absorption in chromium hits 82 percent around 1000 nm. We provide convincing evidences by doing reflection experiment and computational simulations for absorbing MIM part. We also suggest for the first time investigating electric loss tangent of metal or coherently, surface plasmon quality factor of absorbing metals which are reliable tools for engineering different metal layers. They reveal that despite the fact that gold and silver are good plasmonic scatterers in VIS-NIR and reliable absorbers in VIS region, they are not proper choices as absorbers for NIR applications. Once the most optimum absorbing design is pointed out, we integrate it on top of another metal-insulator to form an MIMIM photodetector with tunneling photocurrent path. The final optimized sample consisting of silver - hafnium oxide - chromium - aluminum oxide - silver nanoparticles (from bottom to top) has a dark current of 7nA and a photoresponsivity peak of 0.962 mA/W at 1000 nm and a full width at half maximum of 300 nm, while applied bias is 50 mV and device areas are 300 μm x 600 μm. This photoresponse shows 70 times enhancement compared to former reported spin coated rare nanoparticle MIMIMs.
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    ItemOpen Access
    Synthesis of nanoparticles by laser ablation in liquid method and optical applications
    (2023-08) Taylan, Umut
    Pulsed laser ablation in liquids (PLAL) method is a fast, green, and straightforward method that can be used to synthesize pure nanoparticles free of ligands, capping agents, and waste products. Several types of nanoparticles such as metals, oxides, alloys, semiconductors, composite and compound nanoparticles with spherical or complex morphologies can be synthesized with PLAL method. In this thesis, AuCu nanoparticles for photovoltaic application, AgCu nanoparticles for tunable optical properties, CuS/Cu1.8S nanoparticles for photothermal and photoacoustic application, and (Y0.83Yb0.16Er0.01)2O3 nanoparticles for upconversion photoluminescence application are synthesized. The synthesized AuCu nanoparticles are used in organic solar cells and enhanced the photocurrent production, proven by the 21.4% increase in the power conversion efficiency. AgCu nanoparticles show composition and laser fragmentation dependent tunable surface plasmon resonance between 420 nm – 580 nm, giving 160 nm tunability. These nanoparticles also show complex morphologies with Janus nanoparticle and core-shell type configurations. Copper sulphide nanoparticles show a broad absorbance in the NIR region with absorbance peak at 1183 nm. Nanoparticles with 1 mg/mL concentration show a 52.2 °C temperature increase in 3 minutes of 3.23 W/cm2 1080 nm CW laser irradiation. Photoacoustic imaging experiments where copper sulphide nanoparticles are utilized show a significant contrast enhancement compared to ultrasonic imaging at 1 cm depth. The upconversion nanoparticles show an intense red emission at 651 nm from 980 nm laser irradiation and lowered green emission compared to the target material which shows nanoparticles produce more heat compared to the target which can be useful for photoluminescence – photothermal applications.