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Highly efficient mixed-halide mixed-cation perovskite solar cells based on rGO-TiO2 composite nanofibers
摘要： In this investigation, the electrospun reduced graphene oxide-titanium oxide composite nanofibers as an electron transporting materials have been employed for the perovskite solar cells. The synthesized electron transporting materials have been used for the fabrication of mixed-cation lead mixed-halide (FAPbI3)0.85(MAPbBr3)0.15 perovskite solar cells. The influence of reduced graphene oxide on titanium oxide nanofibers and their morphological and electronic properties have been investigated in detail. The optimized device having FTO/Bl-TiO2/rGO4–TiO2/(FAPbI3)0.85(MAPbBr3)0.15/spiro-MeOTAD/Au configuration exhibited 17.66 % power conversion efficiency with an open circuit voltage of 1.070 V, short circuit current density of 22.16 mAcm-2 and fill factor of 0.754. This obtained efficiency is much higher than that of mesoporous- titanium oxide (14.39 %), pristine- titanium oxide nanofibers (15.82 %) and other reduced graphene oxide- titanium oxide composite nanofibers based electron transporting materials.
关键词： electron transporting materials,large grain size,high-efficiency,Perovskite solar cells,role of rGO in TiO2 nanofibers
更新于2025-09-19 17:13:59
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Bifunctional Ultrathin PCBM Enables Passivated Trap States and Cascaded Energy Level toward Efficient Inverted Perovskite Solar Cells
摘要： Inverted perovskite solar cells (PSCs) with C60 framework are known for their common drawback of low power conversion efficiency (PCE) < 20% because of non-radiative recombination and inefficient charge transport at their perovskite interfaces. Here, we report an ultra-thin [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as a cap layer on perovskite films to overcome this issue. Such a functional cap layer efficiently passivates trap states and establishes a gradient energy level alignment onto perovskite, facilitating the efficient charge transfer and extraction. The as-fabricated inverted PSCs capped with such ultra-thin PCBM exhibit a record PCE of 20.07%. After the storage under N2 atmosphere for more than 500 hours, the PCE of PSCs retains over 85% of its initial level. Our work provides an effective method to upgrade inverted PSCs with the C60 framework with improved efficiency and stability.
关键词： Defect passivation,Cascaded energy level,Interface Engineering,Inverted Perovskite solar cell,Ultra-thin PCBM,High efficiency
更新于2025-09-19 17:13:59
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High-Efficiency Nonfullerene Organic Solar Cells Enabled by 1000 nm Thick Active Layers with a Low Trap-State Density
摘要： The high-efficient organic solar cells (OSCs) with thicker active layers are potential candidates for large-area solar panels fabrication. The low charge carrier mobility of the photoactive materials has been identified as the major problem hindering photovoltaic performance of the thick-film OSCs. In this study, high performance of ultra-thick film organic solar cells employing a non-fullerene acceptor BTP-4Cl and a polymer donor PBDB-TF is demonstrated. Two blends (PBDB-TF:BTP-4Cl and PBDB-TF:IT-4F) show comparable mobilities and excellent photovoltaic characteristics in thin-film devices; while in the 1000-nm-thick devices, although they both exhibit desirable and balanced mobilities, the PBDB-TF:BTP-4Cl-based blend possesses lower trap-state density than the IT-4F-based counterpart, leading to lower trap-assist recombination, longer carrier lifetime, and thus a much higher short circuit current density in the device. As a result, the BTP-4Cl-based 1000-nm-thick OSC achieves a remarkable PCE of 12.1%, which greatly outperforms the IT-4F-based devices (4.72%). What is more, for a 1000-nm thick device with active area of 4 cm2, a promising efficiency of 10.1% was obtained, showing its great potential in future large-scale production.
关键词： trap-state density,ultra-thick active layers,high efficiency,non-fullerene organic solar cells,charge carrier mobility
更新于2025-09-19 17:13:59
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Triarylboron-based TADF emitters with perfluoro substituents: high-efficiency OLEDs with a power efficiency over 100 lmW <sup>a??1</sup>
摘要： We report boron-based thermally activated delayed fluorescence (TADF) emitters that can lead to high-efficiency organic light-emitting diodes (OLEDs) with high power efficiency and low driving voltage. Ortho-carbazole-appended triarylboron compounds (2–7), in which perfluoroalkyl (CF3 and C3F7) or perfluoroaryl (4-CF3C6F4) groups are attached as secondary acceptors, are prepared and characterized. The compounds exhibit a light greenish to yellow emission in toluene with high photoluminescence quantum yields up to 100%. The twisted donor (D)–acceptor (A) structure, as evidenced by both the X-ray crystal structures and theoretically optimized structures, leads to a small energy splitting (ΔEST < 0.1 eV) between the excited singlet and triplet states, giving rise to strong TADF. High-efficiency TADF-OLEDs are realized with the CF3- and 4-CF3C6F4-substituted compounds as emitters. The optimized OLEDs based on the CF3-substituted emitter (5) show a high external quantum efficiency of 29.9% with a low turn-on voltage of 2.35 V. In particular, the devices achieve an ultrahigh power efficiency (PE) of 123.9 lm W?1 without any light-outcoupling enhancement, which is among the best PE values for the reported TADF-OLEDs. The devices also maintain a high PE at the practical brightness, such as 100 cd m?2 (118.7 lm W?1) and 1,000 cd m?2 (82.3 lm W?1).
关键词： perfluoro substituents,OLED,TADF,high efficiency,Triarylboron
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW) - London, United Kingdom (2019.6.18-2019.6.21)] 2019 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW) - A Phase-controlled Stacked-transmitter Wireless Power Transfer System for Magnetic Field Beamforming
摘要： While rate–distortion optimized quantization (RDOQ) technique provides nontrivial coding gain in High Efficiency Video Coding (HEVC), it also involves considerable computations, whereby the complexity of quantization is significantly increased. In this paper, two schemes (the RDOQ bypass decision and the simplified level adjustment) are investigated to reduce the complexity of the quantization process in HEVC with RDOQ. The RDOQ bypass decision method initially selects the transform blocks for which the RDOQ is expected to give less/or no coding gain and enables the conventional uniform scalar quantization to be applied to these transform blocks instead of the RDOQ. The simplified level adjustment method only estimates the difference in rate–distortion costs among the candidate quantization levels to enable the encoder to select an optimal quantization level at a much reduced computational cost. Furthermore, the proposed simplified level adjustment scheme is designed so that it can be implemented in lookup tables. Experimental results show that the proposed fast method achieves 14.3% quantization complexity reduction in all intra main conditions, 15.2% in the random access main condition, and 14.9% in the low delay main condition on average with virtually no coding loss compared with the conventional quantization process with the RDOQ.
关键词： High Efficiency Video Coding (HEVC),Fast quantization,rate–distortion optimized quantization (RDOQ)
更新于2025-09-19 17:13:59
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Processing Friendly Slot-die Cast Non-Fullerene Organic Solar Cells with Optimized Morphology
摘要： The power conversion efficiencies (PCEs) of spin-coated organic solar cells (OSCs) have increased rapidly in recent years. However, spin-coating shows poor reproducibility for large-scale production. Slot-die coating, a lab-scale version of roll-to-roll fabrication, has been considered as the most suitable technique for the production of future large-area commercial devices. For this, highly efficient slot-die fabricated devices are required to approach the performance of spin cast OSCs. We present here, a non-fullerene OSC device utilizing PBDB-T:i-IEICO-4F blend, fabricated by slot-die coating without post treatment in the ambient conditions. Device showed an impressive PCE of 12.5%, which is one of the highest reported performance for slot-die coated OSC devices. Compared to spin-coated and blade-coated films with optimized thermal annealing time, the films fabricated by slot-die coating (without any treatment) exhibit not only the highest degree of crystallinity and face-on orientation, but also the smallest domain size and the purest phase, towards enhanced and balanced carrier mobilities. An enhanced excited state charge generation has been attributed from transient charge kinetics using ultrafast spectroscopic signatures. Optimized slot-die coated devices exhibit excellent tolerance for increased thickness of photoactive layer, attributing to favorable molecular packing. We used slot-die coating as one simple fabrication technique, being capable of yielding highly efficient OSCs.
关键词： processing friendly,high efficiency,slot-die coating,organic solar cells,thick film
更新于2025-09-19 17:13:59
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Insight into the Efficiency and Stability of All-Polymer Solar Cells Based on Two 2D-Conjugated Polymer Donors: Achieving High Fill Factor of 78%
摘要： Achieving high fill factor (FF) is a great challenge for the all polymer solar cells (all-PSCs) since the FF can be influenced by numerous complicated factors. In this work, two medium bandgap 2D-conjugated copolymers J61 and J71 with varied side chains were utilized as donor to construct efficient all-PSCs with the typical electron-withdrawing polymer N2200 as acceptor. Eventually, moderate photovoltaic performance was obtained for J61:N2200 device with power conversion efficiency (PCE) of 6.58% and FF of 60.18%. While the J71:N2200-based all-PSCs delivered an outstanding PCE of 9.31% with an unprecedented FF of 78.00%. To the best of our knowledge, such an FF of 78% represents a record value for binary all-PSCs systems, which demonstrates that the all-PSCs can realize excellent FF comparable to other PSCs systems. The favorable blends morphology, molecular orientation, balanced charge transport and suppressed recombination together contributed to the remarkable photovoltaic performance of J71:N2200 devices. In addition, relatively weak thickness-dependence of photovoltaic property and excellent long-term device stabilities (in N2 and air, respectively) were observed for the J71:N2200 all-PSCs. These results reveal that J71 with trialkylsilyl side chains is a promising polymer donor candidate for developing high performance all-PSCs for future practical application.
关键词： high efficiency,fill factor,stability,all-polymer solar cells,donor
更新于2025-09-19 17:13:59
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Highly efficient organic photovoltaics with enhanced stability through the formation of doping-induced stable interfaces
摘要： Flexible organic photovoltaics (OPVs) are promising power sources for wearable electronics. However, it is challenging to simultaneously achieve high efficiency as well as good stability under various stresses. Herein, we demonstrate the fabrication of highly efficient (efficiency, 13.2%) and stable OPVs based on nonfullerene blends by a single-step postannealing treatment. The device performance decreases dramatically after annealing at 90 °C and is fully recovered after annealing at 150 °C. Glass-encapsulated annealed OPVs show good environmental stability with 4.8% loss in efficiency after 4,736 h and an estimated T80 lifetime (80% of the initial power conversion efficiency) of over 20,750 h in the dark under ambient condition and T80 lifetime of 1,050 h at 85 °C and 30% relative humidity. This environmental stability is enabled by the synergetic effect of the stable morphology of donor/acceptor blends and thermally stabilized interfaces due to doping. Furthermore, the high efficiency and good stability are almost 100% retained in ultraflexible OPVs and minimodules which are mechanically robust and have long-term operation capability and thus are promising for future self-powered and wearable electronics.
关键词： nonfullerene acceptor,environmental stability,ultraflexible devices,organic photovoltaics,high efficiency
更新于2025-09-19 17:13:59
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Inverted Planar Perovskite Solar Cells Based on NiO <sub/>x</sub> Nano Film with Enhanced Efficiency and Stability
摘要： The organometal halide perovskite (OHP) materials have attracted much attention throughout the world due to their superb optoelectronic properties. Tremendous progress has been made in the OHP based solar cells with increased efficiency from 3.8% to 24.2% within the last decade, benefiting from efforts in the photovoltaic field. However, all the OHP solar cells with highest efficient are based on a normal mesoporous structure with TiO2 at the bottom, which needs high temperature process. The inverted planar structure OHP solar cells based on PEDOT:PSS suffer from low efficiency (lower than 15%) and inferior stability due to degradation of PEDOT:PSS in ambient air. Herein, we employed sol–gel method to fabricate a NiOx nano film as the hole transporting layer for inverted OHP solar cells. The device performance based on PEDOT:PSS and NiOx were systematically investigated. It was found that the perovskite films on NiOx film had larger grain size and thus lower defects’ density. The Capacitance–Voltage measurement indicated that the device based on NiOx exhibited larger built-in potential, which significantly enhanced the open-circuit potential of the OHP solar cells. Furthermore, the solar cell based on NiOx nano film exhibited excellent stability compared with the PEDOT:PSS based device, due to robust property of NiOx in ambient air.
关键词： Stability,Perovskite Solar Cell,Large Grain Size,NiOx Nano Film,High Efficiency
更新于2025-09-19 17:13:59
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PCE11-based polymer solar cells with high efficiency over 13% achieved by room-temperature processing
摘要： With the emergence and rapid development of new non-fullerene acceptors (NFAs), bulk-heterojunction polymer solar cells (BHJ-PSCs) have achieved high power conversion efficiencies (PCEs) over 16%. Developing effective methods to fabricate high-performance thick-film PSCs is important to meet the requirements of the future roll-to-roll commercial production. PffBT4T-2OD (PCE11) as the most promising temperature-dependent aggregation (TDA) donor with high crystallinity has achieved high performance at high film thickness, which, however, needs at high processing temperature and is detrimental for practical production of large-area PSCs. We designed NFAs, ZITI-N-CH3, ZITI-N-C8H17, and ZITI-N-EH containing different side chains. Because of the excellent miscibility of the TDA-polymer PffBT4T-2OD and ZITI-N-R, the devices can be fabricated at room temperature, achieving a medium PCE of 8.78% for ZITI-N-CH3-based PSC, a high PCE of 12.13% for ZITI-N-C8H17-based PSC and a superior PCE of 13.07% for ZITI-N-EH-based PSC, which is attributed to the smallest domain size and highest crystallization for PffBT4T-2OD:ZITI-N-EH blend. The PCE of 13.07% is the highest among the TDA polymer-based PSCs, which can be maintained at 12.35% at the high thickness of 200 nm. This work provides an important guideline to develop high-performance thick-film TDA-polymer-based non-fullerene PSCs at mild processing conditions.
关键词： temperature-dependent aggregation,room-temperature processing,polymer solar cells,high efficiency,non-fullerene acceptors
更新于2025-09-19 17:13:59