Photonic technologies continue to drive the quest for new optical materials with unprecedented responses. A major frontier in this field is the exploration of nonlocal (spatially dispersive) materials, going beyond th...
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Electron transport materials (ETM) play an important role in the improvement of efficiency and stability for inverted perovskite solar cells (PSCs). This work reports an efficient ETM, named PDI‐C 60 , by the combina...
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Electron transport materials (ETM) play an important role in the improvement of efficiency and stability for inverted perovskite solar cells (PSCs). This work reports an efficient ETM, named PDI‐C 60 , by the combination of perylene diimide (PDI) and fullerene. Compared to the traditional PCBM, this strategy endows PDI‐C 60 with slightly shallower energy level and higher electron mobility. As a result, the device based on PDI‐C 60 as electron transport layer (ETL) achieves high power conversion efficiency (PCE) of 18.6 %, which is significantly higher than those of the control devices of PCBM (16.6 %) and PDI (13.8 %). The high PCE of the PDI‐C 60 ‐based device can be attributed to the more matching energy level with the perovskite, more efficient charge extraction, transport, and reduced recombination rate. To the best of our knowledge, the PCE of 18.6 % is the highest value in the PSCs using PDI derivatives as ETLs. Moreover, the device with PDI‐C 60 as ETL exhibits better device stability due to the stronger hydrophobic properties of PDI‐C 60 . The strategy using the PDI/fullerene hybrid provides insights for future molecular design of the efficient ETM for the inverted PSCs.
Cryogel based encapsulation was attempted to entrap oil phase (containing curcumin) with a ternary system of colloidal chitosan, κ-carrageenan, and carboxy methylcellulose sodium salt (NaCMC). The cryotropic gel form...
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Cryogel based encapsulation was attempted to entrap oil phase (containing curcumin) with a ternary system of colloidal chitosan, κ-carrageenan, and carboxy methylcellulose sodium salt (NaCMC). The cryotropic gel formation was investigated by varying the cooling rate during freezing and type of polymer suspension. The microstructure of the resulting curcumin cryogels revealed oil droplets entrapped in the cryogel matrix. The encapsulation yield for two types of suspension was found to vary from 83.89 to 99.37%. Controlled release of the curcumin in an aqueous system could be maintained for 4 days, and the released amount of curcumin was found to vary from 41.1-59.9%. The encapsulation yield as well as the released pattern and amount of curcumin were influenced by the cooling protocol used during freezing. The release patterns were found to be sensitive to the ambient aqueous pH and, interestingly, either a burst release or a first order release was achievable simply by changing the freezing condition. These results suggested that freezing could modify the gel formation of the present cryogel, and the resulting structural modification evidently controlled the oil encapsulation manner. The present ternary system (chitosan, κ- carrageenan, and NaCMC) is an interesting matrix for designing controlled release system in a food system.
This paper introduces a new cantilever type multi-source energy harvester generating electric power from both ambient heat and vibration. Harvesting energy from vibration was realized by electromagnetic conversion, wh...
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This paper introduces a new cantilever type multi-source energy harvester generating electric power from both ambient heat and vibration. Harvesting energy from vibration was realized by electromagnetic conversion, whereas the energy generation from heat was supplied by making use of Seebeck effect of Cr–Al thermocouples implemented on the microcantilevers. The measured average Seebeck coefficient is 12 μV/K per thermocouple. A total voltage of 3.3 mV was generated from the thermoelectric part and 13.4 mV from the electromagnetic part of the device. Measured total power from the fabricated chip is 1.91 nW (1.12 nW from vibration, 0.79 nW from thermoelectric).
This paper presents a new mechanical frequency up-conversion (FUC) mechanism for harvesting energy from external low frequency vibrations. The structure consists of a magnet placed on a support, a polystyrene cantilev...
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This paper presents a new mechanical frequency up-conversion (FUC) mechanism for harvesting energy from external low frequency vibrations. The structure consists of a magnet placed on a support, a polystyrene cantilever carrying a pick-up coil, and a mechanical barrier which converts low frequency vibrations to a higher frequency, hence increasing the efficiency of the system. The tested structure proved to give 20.3 mV and 68.7 ¿W RMS power output by up-converting 10 Hertz external vibration to 643 Hertz. The tests with different magnet configurations and cantilever lengths showed that horizontal cascading of the magnets improve the performance whereas an optimum cantilever length exits for the maximum generated power. An analytical model is also developed for the system, supporting the test results. The proposed structure is a good candidate to be realized by using microfabrication techniques in terms of generated voltage and power levels.
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