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Electrospray deposited MoS2 nanosheets as an electron transporting material for high efficiency and stable perovskite solar cells
摘要： For perovskite solar cells (PSCs), the development of low cost, stable and e?cient electron transport materials (ETMs) is of prime consideration. Here, we have introduced a scalable electrospraying technique for the direct deposition of hydrotermally synthesized two-dimensional (2D) MoS2 nanosheets ETMs, onto the ?uorine-doped tin oxide (FTO) glass susbtarte to use in PSCs with reduces hysteresis, improved ambient stability and high e?ciency. The PSCs fabricated with electrospray deposited MoS2 nanosheets demonstrate the maximum power conversion e?ciency (PCEmax) of 16.17%, that is comparable to the PCEs achieved from compact SnO2 and TiO2 ETM based PSCs. The current ?ndings present a new route for the construction of stable and e?cient PSCs based on a low-cost and solution- processed MoS2 nanosheets ETMs.
关键词： Thin ?lms,Electrospray,Perovskite solar cells,Hysteresis-free,MoS2 nanosheets
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE International Electron Devices Meeting (IEDM) - San Francisco, CA, USA (2018.12.1-2018.12.5)] 2018 IEEE International Electron Devices Meeting (IEDM) - Demonstration of High-speed Hysteresis-free Negative Capacitance in Ferroelectric Hf<inf>0.5</inf>Zr<inf>0.5</inf>O<inf>2</inf>
摘要： We report the experimental observation of hysteresis-free negative capacitance (NC) in thin ferroelectric Hf0.5Zr0.5O2 (HZO) films through high-speed pulsed charge-voltage measurements. Hysteretic switching is suppressed by the addition of thin Al2O3 layers on top of the HZO to prevent the screening of the polarization. We observe an S-shaped polarization-electric field dependence without hysteresis in agreement with Landau theory, which enables direct extraction of NC modeling parameters for ferroelectric HZO. Hysteresis-free NC is demonstrated down to 100 ns pulse widths limited only by our measurement setup. These results give critical insights into the physics of ferroelectric NC and practical NC device design using ferroelectric HZO.
关键词： hysteresis-free,Hf0.5Zr0.5O2,ferroelectric,negative capacitance,pulsed measurements,Landau theory
更新于2025-09-19 17:15:36
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Doped but stable: spirobisacridine hole transporting materials for hysteresis-free and stable perovskite solar cells
摘要： Four spirobisacridine (SBA) hole-transporting materials were synthesized and employed in perovskite solar cells (PSC). The molecules bear electronically inert alkyl chains of different length and bulkiness, attached to in-plane N-atoms of nearly orthogonal spiro-connected acridines. Di-p-methoxyphenylamine (DMPA) substituents tailored to the central SBA-platform define electronic properties of the materials mimicking the structure of the benchmark 2,2’,7,7’-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9’-spirobifluorene (spiro-MeOTAD), while the alkyl pending groups affect molecular packing in thin film and affect long-term performance of PSCs. Devices with SBA-based hole transporting layers (HTL) attain efficiencies on par with spiro-MeOTAD. More importantly, solar cells with the new HTMs are hysteresis-free and demonstrate good operational stability, despite being doped as spiro-MeOTAD. The best performing MeSBA-DMPA retained 88% of the initial efficiency after 1000 h ageing test under a constant illumination. The results clearly demonstrate: SBA-based compounds are potent candidates for a design of new HTMs for PSCs with improved longevity.
关键词： perovskite solar cells,hysteresis-free,spirobisacridine,operational stability,hole-transporting materials
更新于2025-09-12 10:27:22
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Hysteresis-Free Hexagonal Boron Nitride Encapsulated 2D Semiconductor Transistors, NMOS and CMOS Inverters
摘要： Graphene and subsequently discovered layered semiconducting transition metal dichalcogenides (TMDCs) exhibit numerous exotic physical properties and broad potential device applications. These 2D semiconducting TMDCs have become particularly interesting in next-generation electronic device applications due to their atomic thickness and nonzero bandgap. However, as there is no bulk volume, the 2D nature makes the electronic transport in these crystals highly sensitive to the environmental conditions, such as humidity, adsorbates, and trapped charges in neighboring dielectrics. Due to this environmental sensitivity, 2D-based circuits and devices suffer from a large and undesirable environment-induced hysteresis, which must be eliminated for reliable operation and computation. By mechanically assembling van der Waals (vdWs) heterostructures and edge-contacted graphite electrodes, the 2D semiconducting channel is sealed completely and protected. Here, hexagonal boron nitride (hBN) encapsulated high-performance, hysteresis-free 2D semiconductor transistors, n-type metal-oxide semiconductor, and complementary metal-oxide semiconductor inverters are fabricated. The hBN encapsulation provides excellent protection of semiconducting n-MoS2 and p-WSe2 from environmental factors, resulting in hysteresis-free 2D electronics characteristics that are necessary for the realization of 2D electronics and computing.
关键词： hysteresis-free,van der Waals (vdWs) heterostructures,inverters,2D materials,transistors
更新于2025-09-09 09:28:46