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Concentration quenching resistant donor-acceptor molecular structure for high efficiency and long lifetime thermally activated delayed fluorescent organic light-emitting diodes via suppressed non-radiative channel
摘要： A molecular design having t-butyl groups surrounding a donor-acceptor type core structure was developed as an approach to obtain high external quantum efficiency by suppressing concentration quenching effect caused by strong intermolecular interaction. The donor-acceptor type core structure was surrounded by six t-butyl groups to separate the donor-acceptor core structure between molecules. A heptazine acceptor and a diphenylamine donor based thermally activated delayed fluorescent emitter protected by the multiple t-butyl units achieved maximum external quantum efficiency of 32.6% at 1% doping concentration and 23.0% even at a high doping concentration of 20% by reducing concentration quenching effect. Furthermore, the lifetime of the thermally activated delayed fluorescent devices was also improved relative to that of the previous emitter with the same acceptor. The external quantum efficiency and device lifetime are better than any other results reported in the orange TADF OLEDs.
关键词： Thermally activated delayed fluorescence,Lifetime,T-butyl,Organic light-emitting diodes,High efficiency
更新于2025-09-23 15:21:01
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Effect of PbS quantum dot-doped polysulfide nanofiber gel polymer electrolyte on efficiency enhancement in CdS quantum dot-sensitized TiO2 solar cells
摘要： Quantum dot-sensitized solar cells (QDSSCs) are among the most promising low cost third generation solar cells. Semiconductor quantum dots have unique properties such as high molar extinction coefficients, tunable energy gap by the quantum confinement effect and the ability of multiple exciton generation. In this study, stable CdS QDSSCs were fabricated by using polysulfide liquid electrolytes and also by using cellulose acetate nanofiber-based gel electrolytes. Incorporation of PbS Q dots to the liquid or gel electrolyte showed a significant enhancement in solar cell efficiency. Under the simulated light of 100 mW cm-1 the efficiency of the polysulfide liquid electrolyte based CdS QD solar cells increased from 1.19% to 1.51% and the efficiency of the nanofibre gel electrolyte based CdS QD solar cells increased from 0.94 % to 1.46% due to the incorporation of 5% (wt/wt) PbS Q dots into the respective electrolytes. The efficiency increase has been attributed to the increase in short circuit photocurrent density due to increased sulfide ion (S2-) conductivity evidently caused by indirect ionic dissociation facilitated by PbS QDs.
关键词： Sulfide ion conductivity,Nanofibre gel electrolyte,Efficiency enhancement,Quantum dot sensitized solar cells,Quantum dot doped electrolyte
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Dynamic Real-Time Simulation Approach to Power Management Modelling for CubeSat Applications
摘要： As green communication becomes an inevitable trend for future 5G wireless networks, how to maximize the energy efficiency (EE) of device-to-device (D2D) communication has drawn extensive attention recently. However, most of existing works only optimize the EE in the single-cell scenario, while little attention is paid to maximizing the EE of the whole cellular network underlaid with D2D communication with randomly distributed users on multiple bands. In this paper, we first consider the whole cellular network underlaid with D2D communication on multiple bands and derive the exact expressions of the successful transmission probabilities, the average sum rate and the EE based on stochastic geometry theory. Then, we formulate the optimization problem of maximizing the EE subject to four constraints regarding to transmission power and outage probabilities, and the non-convexity of this problem is also verified. After that, by exploiting the objective function property of being the sum of several functions, we propose a derivative-based algorithm to solve this non-convex optimization problem. Our theoretical analysis shows that the computational complexity of the proposed algorithm is significantly lower than that of the conventional branch and bound algorithm. Finally, simulation results demonstrate that the proposed algorithm can achieve the near-optimal EE with much better performance than the conventional algorithm.
关键词： 5G,D2D communication,energy efficiency,stochastic geometry
更新于2025-09-23 15:21:01
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Development of Combinatorial Pulsed Laser Deposition for Expedited Device Optimization in CdTe/CdS Thin-Film Solar Cells
摘要： A combinatorial pulsed laser deposition system was developed by integrating a computer controlled scanning sample stage in order to rapidly screen processing conditions relevant to CdTe/CdS thin-film solar cells. Using this system, the thickness of the CdTe absorber layer is varied across a single sample from 1.5 ??m to 0.75 ??m. The effects of thickness on CdTe grain morphology, crystal orientation, and cell efficiency were investigated with respect to different postprocessing conditions. It is shown that the thinner CdTe layer of 0.75 ??m obtained the best power conversion efficiency up to 5.3%. The results of this work shows the importance that CdTe grain size/morphology relative to CdTe thickness has on device performance and quantitatively exhibits what those values should be to obtain efficient thin-film CdTe/CdS solar cells fabricated with pulsed laser deposition. Further development of this combinatorial approach could enable high-throughput exploration and optimization of CdTe/CdS solar cells.
关键词： combinatorial pulsed laser deposition,power conversion efficiency,grain morphology,CdTe/CdS thin-film solar cells,device optimization,crystal orientation
更新于2025-09-23 15:21:01
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Ternary Organic Solar Cells Based on two Non-fullerene Acceptors with Complimentary Absorption and Balanced Crystallinity
摘要： The ternary blend structure has been demonstrated as an effective approach to increase the power conversion efficiency of organic solar cells. An effective approach to enhance the power conversion efficiency of ternary solar cells is based on two non-fullerene acceptors with complimentary absorption range and balanced crystalinity. In this work, by introducing a high crystallinity small-molecule acceptor, named C8IDTT-4Cl with appropriate alkyl side chains into a low crystalline blend of conjugated polymer donor PBDT-TPD and fused-ring electron acceptor ITIC-4F. A ternary device based on the blend PBDT-TPD:ITIC-4F:C8IDTT-4Cl exhibits a best power conversion efficiency of 9.51% with a simultaneous improvement of the short-circuit current density to 18.76 mA cm-2 and the fill factor up to 67.53%. The absorption onset for C8IDTT-4Cl is located at 900 nm, so that the well complementary light absorption is beneficial to the photocurrent. In addition, the existence of high crystallinity C8IDTT-4Cl in the ternary device is found helpful to modulate crystallinity, improve heterojunction morphologies and stacking structure, therefore to realize higher charge mobility and better performance.
关键词： Non-fullerene Acceptors,Ternary Organic Solar Cells,Power Conversion Efficiency,Complimentary Absorption,Balanced Crystallinity
更新于2025-09-23 15:21:01
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Large-Area Perovskite Solar Cells
摘要： Perovskite solar cells (PSCs) have been attracting much attention during the past years due to the advantages of perovskite materials such as high light absorption coefficient, excellent charge mobility, long charge diffusion length, tunable direct band gap, low cost, etc., exhibiting great potential as the next-generation photovoltaic technology [1-3]. The certificated power conversion efficiency (PCE) as high as 25.2% has been achieved for single-junction PSCs with an active area of 0.0937 cm2 (https://www.nrel.gov/pv/assets/pdfs/best-research-cell-efficiencies.20200128.pdf). However, the state-of-the-art PCE of the large-area PSCs with the active area larger than 10 cm2 (minimodules) is 18.04% (19.276 cm2) (http://solar.in-en.com/html/solar-2352538.shtml), which is still much lower than the value of 79 cm2 silicon solar cell with the PCE of 26.7%. Fig. 1 shows nearly 50 published papers during the past years about the research progress on the PCEs of mesoporous and planar (normal and inverted) structural large-area PSC minimodules, of which the typical active area is from 10 to 100 cm2, and the five cases with the size larger than 100 cm2 are labelled. It should be mentioned that the reported results from companies are not included in Fig. 1 because the detailed device information is not clear. PSC minimodules were first reported in 2014, and much progress has been achieved subsequently. At present, it could normally achieve mesoporous or planar structural PSC minimodules with the PCEs between 15% and 18%. Meanwhile, stability is another very important factor that directly determines the actual applications of PSCs [2,4]. In order to accelerate the commercialization of PSCs, it is highly desired to further develop large-area PSCs and modules with high efficiency and good stability.
关键词： Stability,Perovskite solar cells,Commercialization,Large-area,Efficiency
更新于2025-09-23 15:21:01
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Numerical analysis of earth-abundant Cu2ZnSn(SxSe1-x)4 solar cells based on Spectroscopic Ellipsometry results by using SCAPS-1D
摘要： Mixed chalcogenide CZTSSe with earth abundant elements, inexpensive, environmental-friendly and impressive photovoltaic performance is a promising absorber material for kesterite thin film solar cells of third generation. In this work, a numerical simulation of p-CZTSSe/n-CdS heterojunction solar cells have been presented using one dimensional Solar Capacitance Simulator. The influence of composition, absorber thickness, defect density and working temperature on Voc, Jsc, FF and power conversion efficiency has been investigated. The optimized cell shows 23.16% efficiency with a Voc ~ 0.724 V corresponding to 40% of the ratio.
关键词： Composition and Spectroscopic Ellipsometry,Absorption coefficient,CZTSSe,Thin film solar cell,Third generation,SCAPS,Efficiency
更新于2025-09-23 15:21:01
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Aggregation-induced Emission Polymers for High Performance PLEDs with Low Efficiency Roll-off
摘要： As the congener of organic light-emitting diodes, polymeric light-emitting diodes (PLEDs) possess a number of distinct merits such as low-cost wet fabrication process, which enable them applicable in large-area flexible display and lighting fields. However, most emissive polymers used in PLEDs suffer from the aggregation-caused quenching (ACQ) effect, which makes the device show large efficiency roll-off. In this work, two polymers of pTPE-TPA-Cz and pTPE-TPA-Flu featuring aggregation-induced emission (AIE) characteristics were facilely synthesized through Suzuki-Miyaura polycoupling reaction by incorporating the AIE unit of TPE-TPA in their main chains. The resultant polymers possess good film-forming ability, excellent thermal stability and high photoluminescence quantum yields (PLQY) in their film states, facilitating the fabrication of PLEDs through solution process. Indeed, the PLEDs using pTPE-TPA-Cz and pTPE-TPA-Flu as emitting layers (EMLs) could achieve a maximum external quantum efficiency (EQE) of 3.26% (doped EML) and current efficiency of 3.69 cd A-1 (non-doped EML). Notably, all the devices exhibit a quite low efficiency roll-off. This work indicates that AIE polymers are ideal candidates for the construction high performance PLEDs with low efficiency roll-off.
关键词： Aggregation-induced emission,Photoluminescence quantum yields,Solution process,Efficiency roll-off,Polymeric light-emitting diodes
更新于2025-09-23 15:21:01
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Thiazolo[5,4- <i>d</i> ]thiazole-based organic sensitizers with improved spectral properties for application in greenhouse-integrated dye-sensitized solar cells
摘要： Organic photosensitizers especially designed for producing semitransparent dye-sensitized solar cells (DSSCs) for greenhouse integration were prepared by introduction of different heterocyclic moieties into the thiazolo[5,4-d]thiazole-molecular scaffold. The aim was that of improving their light absorption capability in the green part of the visible spectrum while maintaining a good transparency in the blue and red regions, where the photosynthetic response is maximized. A short and efficient synthetic approach, featuring two consecutive C-H activation reactions in a one-pot procedure as key steps, was used. Based on their spectroscopic and electrochemical characterization, two of dyes prepared appeared especially suitable for greenhouse-integrated photovoltaics. The corresponding semitransparent DSSCs yielded 5.6-6.1% power conversion efficiencies, which were largely superior to those provided by other organic dyes previously proposed for the same application.
关键词： organic photosensitizers,light absorption,photovoltaic efficiency,dye-sensitized solar cells,greenhouse integration,thiazolo[5,4-d]thiazole,transparency
更新于2025-09-23 15:21:01
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An inverted ZnO/P3HT:PbS bulk-heterojunction hybrid solar cell with a CdSe quantum dot interface buffer layer
摘要： An inverted bulk-heterojunction (BHJ) hybrid solar cell having the structure ITO/ZnO/P3HT:PbS/Au was prepared under ambient conditions and the device performance was further enhanced by inserting an interface buffer layer of CdSe quantum dots (QDs) between the ZnO and the P3HT:PbS BHJ active layer. The device performance was optimized by controlling the size of the CdSe QDs and the buffer layer thickness. The buffer layer, with an optimum thickness and QD size, has been found to promote charge leading to an increased open-circuit voltage (VOC), extraction and reduces interface recombinations, short circuit current density (JSC), fill factor (FF) and power conversion efficiency (PCE). About 40% increase in PCE from 1.7% to 2.4% was achieved by the introduction of the CdSe QD buffer layer, whose major contribution comes from a 20% increase of VOC.
关键词： CdSe quantum dots,inverted bulk-heterojunction,interface buffer layer,hybrid solar cell,power conversion efficiency
更新于2025-09-23 15:21:01