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A Facile Microwave-Assisted Hydrothermal Synthesis of Graphene Quantum Dots for Organic Solar Cell Efficiency Improvement
摘要： Carbon-based nanomaterials have successively remained at the forefront of different research fields and applications for years. Understanding of low-dimension carbon material family (CNT, fullerenes, graphene, and graphene quantum dots) has arrived at a certain extension. In this report, graphene quantum dots were synthesized from graphene oxide with a microwave-assisted hydrothermal method. Compared with conventional time-consuming hydrothermal routes, this novel method requires a much shorter time, around ten minutes. Successful formation of quantum dots derived from graphene sheets was verified with microscopic and spectroscopic characterization. Nanoparticles present a diameter of about 2-8 nm, blue emission under ultraviolet excitation, and good dispersion in polar solvents and can be collected in powder form. The synthesized graphene quantum dots were utilized as a hole transport layer in organic solar cells to enhance the cell quantum efficiency. Such quantum dots possess energy levels (Ec and Ev) relevant to HOMO and LUMO levels of conductive polymers. Mixing P3HT:PCBM polymer and graphene quantum dots of sufficient extent notably helps reduce potential difference at interfaces of the two materials. Overall efficiency consequently advances to 1.43%, an increase of more than 44% compared with pristine cells (0.99%).
关键词： microwave-assisted hydrothermal synthesis,organic solar cells,graphene quantum dots,efficiency improvement
更新于2025-09-23 15:19:57
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Zwitterion Effect of Cow Brain Protein towards Efficiency Improvement of Dye-Sensitized Solar Cell (DSSC)
摘要： Dye-Sensitized Solar Cell (DSSC) constitutes a solar cell using natural dyes from plants that are adsorbed in semiconductors to convert solar energy into electrical energy. DSSC has relatively inexpensive fabrication costs, is easy to produce, works in visible light, and is environmentally friendly. The disadvantage of DSSC is that its e?ciency is still low compared to silicon solar cells. This low e?ciency is due to obstacles in the ?ow of electric current on DSSC. In this study, DSSC has been successfully fabricated with the deposition of clathrin protein from cow brain. The zwitterions e?ect of protein on cow brain is able to reduce resistance and increase electric current on DSSC. The zwitterions e?ect of cow brain protein that ?lls gaps or empty spaces between TiO2 particles generates acidic reactions (capturing electrons) and bases (releasing electrons); hence, proteins in the cow brain are able to function as electron bridges between TiO2 molecules and generate an increase in electric current in DSSC. The method used in this research was to deposit clathrin protein from cow brain in a porous TiO2 semiconductor with a concentration of 0%, 25%, 50%, and 75%. Tests carried out on DSSC that have been performed were X-Ray Di?ractometer (XRD) testing to determine the crystal structure formed, Fourier Transform Infrared Spectroscopy (FTIR) testing to determine the functional groups formed on DSSC, Scanning Electron Microscopy (SEM) testing to determine the surface morphological characteristics of the DSSC layer, and testing the e?ciency using AM 1.5 G solar simulator (1000 W/m2) to determine the e?ciency changes that occur in DSSC. From the XRD test results by increasing the concentration of cow brain protein in DSSC, the structure of amino acid crystals also increased and the crystal size increased with the largest crystal size of 42.25 nm at the addition of 75% of cow brain protein. FTIR test results show that the addition of cow brain protein will form functional protein-forming amino groups on DSSC. FTIR analysis shows the sharp absorption of energy by protein functional groups in the FTIR spectrum with increasing concentration of cow brain protein in DSSC. The SEM test results show that the concentration of additional molecules of protein deposited into TiO2 increases and the cavity or pore between the TiO2 molecules decreases. The reduction of cavities in the layers indicates that protein molecules ?ll cavities that exist between TiO2 molecules. From the results of testing using AM 1.5 G solar simulator (1000 W/m2), the highest e?ciency value is 1.465% with the addition of 75% brain protein concentration.
关键词： DSSC,efficiency improvement,clathrin protein,zwitterions effect,TiO2,Dye-Sensitized Solar Cell,cow brain
更新于2025-09-19 17:13:59
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Effects of 1,2-ethanedithiol concentration on performance improvement of quantum-dot LEDs
摘要： We report systematic e?ciency variations of green-emitting CdSe@ZnS quantum-dot (QD) LEDs (QLEDs) in response to in situ treatments with 1,2-ethanedithiol (EDT) solutions at various concentrations. The main e?ect of in situ EDT treatment on a QD layer spin-coated onto a ZnO layer was vacuum-level shift due to dipole moments on the surface of the QD layer and at the interface between QD and ZnO layers. Competing contributions of these dipole moments were responsible for changes in energy level con?gurations and, accordingly, electron and hole barriers that resulted in discrepancies in electron- and hole-current variations. QLED e?ciency was best when treated with an EDT solution of 4 mM, attributable to the largest increase in the hole- to electron current ratio. The maximum luminous yield of the 4 mM EDT-treated QLED was 5.43 cd A(cid:1)1, which is 10 times higher than that of an untreated device. Furthermore, the luminous yield of this treated device remained as high as 2.56 cd A(cid:1)1 at a luminance of 500 cd m(cid:1)2.
关键词： efficiency improvement,vacuum-level shift,dipole moments,quantum-dot LEDs,1,2-ethanedithiol
更新于2025-09-16 10:30:52
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Annual Energy Harvesting of Passively Cooled Hybrid Thermoelectric Generator-Concentrator Photovoltaic Modules
摘要： Approximately 60% of the incident energy is dissipated as heat in conventional concentrator photovoltaic modules. The hybridization with thermoelectric generators (TEGs) aims to recover part of the waste heat and transform it to electricity. Recently, the feasibility of passively cooled designs has been assessed for small sized solar cells (3 mm × 3 mm). It is expected that novel prototypes will be developed according to this concept. However, the existing feasibility studies are based on reference operating conditions, while the behavior of the hybrid modules under changing atmospheric conditions remains unknown. In this article, real atmospheric data of Jaén, Southern Spain, including irradiance, temperature, and spectral data, are used to analyze the behavior of four designs of TEG-concentrator photovoltaic modules: low ZT-low temperature (A), low ZT-high temperature (B), high ZT-low temperature (C), and high ZT-high temperature (D). This behavior is compared with that of a typical concentrator photovoltaic-only module. Results show that, while the global ef?ciency at reference conditions can be enhanced up to 4.75%, the annual averaged global ef?ciency can only be increased up to 4.30%. The results of this article will help to understand the impact of the atmospheric conditions on the real behavior of these structures.
关键词： concentrator photovoltaics (CPV),efficiency improvement,Annual energy,thermoelectric generator (TEG),hybrid system,passive cooling
更新于2025-09-16 10:30:52
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Large Area 23%-Efficient Monolithic Perovskite/Homo-Junction-Silicon Tandem Solar Cell With Enhanced UV Stability Using Down-Shifting Material
摘要： UV induced degradation and parasitic ultraviolet (UV) absorption by the 'sun-facing' carrier transport layer in a perovskite cell hinders stability and electrical performance when the perovskite cell is a top cell for a Si-based tandem. In this work, we tackle these issues by applying textured polydimethylsiloxane (PDMS) films that incorporate a down-shifting material (Ba,Sr)2SiO4:Eu2+ micron phosphor on the front of monolithic perovskite/silicon tandem cells. This film serves multiple purposes: antireflective control for the top cell, light trapping in the Si cell as well as absorbing UV and re-emitting green light with high quantum yield. When applied onto a 4 cm2 monolithic perovskite/silicon tandem solar cell, the power conversion efficiency was improved from 20.1% (baseline device without any anti-reflective film) to 22.3% (device with anti-reflective film but without the phosphors) and to 23.1% (device with down-shifting and antireflective film). The steady-state efficiency of 23.0% and a high FF of 81% achieved by the champion device are the highest values to date for a monolithic perovskite/Si tandem that uses homo-junction-silicon bottom cell. Moreover, results of continuous UV irradiation test show that this composite down-shifting antireflection film significantly enhances the UV stability for the tandem device. This work demonstrates an elegant approach for improving the efficiency and stability for larger area perovskite/silicon tandems.
关键词： perovskite/silicon tandem solar cells,down-shifting material,efficiency improvement,polydimethylsiloxane (PDMS),UV stability
更新于2025-09-16 10:30:52
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[IEEE 2019 3rd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT) - Ankara, Turkey (2019.10.11-2019.10.13)] 2019 3rd International Symposium on Multidisciplinary Studies and Innovative Technologies (ISMSIT) - Use of Hybrid Photovoltaic-Thermoelectric (PV-TE) solar module for Enhancing Overall System Efficiency
摘要： The improvement of the efficiency of the photovoltaic (PV) modules is the focus nowadays of so many researchers. Many test and research were conducted in order to reach that goal. That’s how they came with the idea of a hybrid. Combining the PV module with the thermoelectric module is an innovative approach to improve the efficiency. Thus, not only a part of the solar spectral is exploited as for the PV alone, but a larger spectrum is exploited because the heat too is used. It allows the cooling of the panel and provide an additional power. It was seen also that combining the hybrid with a heat-exchanger (HW) increase the efficiency as well, by changing individually either the PV or the sink of the thermoelectric to reach much better outputs. A comprehensive review on these previous research studies are presented here. Many methods and approaches to enhance the performance of the PV/TE systems are discussed along with mathematical models used. The gaps in existing literature are identified and recommendations for future research are precisely outlined. It is emphasized here that only few experimental studies on PV/TE systems are exist. Therefore, it is highly recommended here that comprehensive experimental studies under real atmospheric conditions should be done with these systems, without neglecting effects of shapes and arrangements of TE materials.
关键词： PV-TE efficiency,PV-TE efficiency improvement,PV-TE hybrid,PV-TE feasibility
更新于2025-09-12 10:27:22
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Simulation of Multilayer Energy Efficient OLEDs for Flexible Electronics Applications
摘要： Organic light emitting (OLEDs) work on electro luminescence principles and these OLEDs are commercially available and can be used in display because of the low power consumption. Proposed research deals with the design of high-efficiency OLEDs, including electrical and optical design of OLEDs. The Luminescent efficiency of bilayer and Triple layer OLED experiment and analysis was done using the Silvaco TCAD tool in this research work. The simulation of electronics and optical features such luminescence power versus anode voltage, anode voltage versus anode current characteristics and exciton state of both bilayer and Triple layer OLEDs were discussed. The physical design, processes as well as principles of OLED has been discussed and operational distribution of Langevin recombination inside proposed structures were acquired and discussed.
关键词： Efficiency Improvement,Organic Light emitting diode (OLEDs),Multilayer,TCAD
更新于2025-09-12 10:27:22
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Perovskite Quantum Dots Exhibiting Strong Hole Extraction Capability for Efficient Inorganic Thin Film Solar Cells
摘要： Inorganic semiconductor Sb2(S,Se)3 possesses a suitable bandgap, environmentally benign elemental composition, and excellent stability, offering ample promise for next-generation low-cost solar cells. Here, we demonstrate that perovskite quantum dots (QDs), including CH3NH3PbBr3 and CsPbBr3, can serve as highly efficient and air-stable hole extraction materials in Sb2(S,Se)3 solar cells. Through a proper pre-treatment of the colloidal QDs, a 25-nm-thick QD film can be obtained with excellent uniformity and charge transport properties. Spectroscopic and photoelectrochemical analysis show that perovskite QDs can effectively extract holes from Sb2(S,Se)3 with suppressed carrier recombination. The perovskite QDs/Sb2(S,Se)3 heterojunction also establishes an increased built-in potential so that open-circuit voltage is pronouncedly enhanced. Finally, the device based on perovskite QDs/Sb2(S,Se)3 heterojunction boosts the efficiency from 4.43% to 7.82%, setting a record value, to the best of our knowledge, in Sb2(S,Se)3 solar cells. Our research manifests another application of perovskite materials and practical strategy toward efficiency improvement of Sb2(S,Se)3 solar cells.
关键词： efficiency improvement,inorganic thin film solar cells,Perovskite quantum dots,Sb2(S,Se)3,hole extraction
更新于2025-09-12 10:27:22
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Efficiency improvement of planar inverted perovskite solar cells by introducing F8BT into PTAA as mixed hole transport layer
摘要： Hole-transport layer (HTL) is a crucial component to influence the crystallization of the perovskite layer which has close photovoltaic efficiency and stability of perovskite relationship with the photovoltaic efficiency and stability of perovskite solar cells (PVSCs). In this work, planar inverted PVSCs employing polytriarylamine (PTAA) HTL mixed with a polymeric material of poly(9,9-dioctyfluorene-co-benzothiazole) (F8BT) are fabricated, and the effect of mixed polymer HTL on the device performance was investigated. After the variation of the F8BT ratio in the mixed HTL, the average power conversion efficiency (PCE) of 14.88 % with negligible hysteresis was achieved and the champion device exhibits a PCE of 15.41 % due to the increased charge carrier extraction and optimized crystallization properties of perovskite. Unsealed planar p-i-n PVSCs with mixed polymer HTL show a 28.8 % incensement in average PCE (14.88 % vs 11.55 %) and over 30 % enhancement in stability at ambient condition for two weeks with respect to control due to the improvement in the crystallinity of perovskite layer and conductivity of polymer layer. This work provides an effective strategy for the development of highly efficient planar PVSC fabricated on mixed polymer HTL.
关键词： Planar perovskite solar cell,F8BT,PTAA,Mixed polymer HTL,Efficiency improvement
更新于2025-09-12 10:27:22