| 1. |
- Glinka, Adam, et al.
(författare)
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Interface Modification and Exceptionally Fast Regeneration in Copper Mediated Solar Cells Sensitized with Indoline Dyes
- 2020
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 124:5, s. 2895-2906
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Tidskriftsartikel (refereegranskat)abstract
- The photovoltaic performance of solar cells sensitized with indoline D205 dye and its new derivative comprising an alkoxysilyl anchoring unit (D205Si) in the [Cu(tmby)(2)](TFSI)(2/1) (tmby = 4,4',6,6'-tetramethyl-2,2'-bipyridine, TFSI = bis(trifluoromethane)sulfonimide) redox couple mediated systems was studied in the presence of various titania/dye/electrolyte interface modifications. Cucurbit[7]uril (CB7) was employed to encapsulate dye molecules, creating an electronically insulating layer, suppressing electron interception by redox mediator, and leading to the increase in the electron lifetime in the titania conduction band. For example, the electron lifetime increased from 2.2 to 6.5 ms upon CB7 encapsulation of D205 cells at 0.9 V voltage. Further, molecular multicapping was optimized to minimize dye desorption and prevent electron recombination. As a result, photovoltaic performance was found to be enhanced by the interface modifications in most cases, especially when applied to the alkoxysilyl anchoring derivative. The charge transfer processes (dye regeneration, titania-dye and titania-redox mediator recombination) in the above-mentioned system and in the reference [Co(bpy)(3)](TFSI)(3/2) (bpy = 2,2'-bipyridine) redox couple mediated systems were investigated by means of small light perturbation electron lifetime measurements, electrochemical impedance spectroscopy, and nanosecond and femtosecond transient absorption spectroscopies. Indoline dyes were also found to be outstandingly fast regenerated by the Cu-based mediator (time constant shorter than 100 ns), which may open new opportunities for sensitizer improvements.
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| 2. |
- Michaels, Hannes, et al.
(författare)
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Dye-sensitized solar cells under ambient light powering machine learning : towards autonomous smart sensors for the internet of things
- 2020
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Ingår i: Chemical Science. - : ROYAL SOC CHEMISTRY. - 2041-6520 .- 2041-6539. ; 11:11, s. 2895-2906
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Tidskriftsartikel (refereegranskat)abstract
- The field of photovoltaics gives the opportunity to make our buildings "smart'' and our portable devices "independent", provided effective energy sources can be developed for use in ambient indoor conditions. To address this important issue, ambient light photovoltaic cells were developed to power autonomous Internet of Things (IoT) devices, capable of machine learning, allowing the on-device implementation of artificial intelligence. Through a novel co-sensitization strategy, we tailored dye-sensitized photovoltaic cells based on a copper(II/I) electrolyte for the generation of power under ambient lighting with an unprecedented conversion efficiency (34%, 103 mu W cm(-2) at 1000 lux; 32.7%, 50 mu W cm(-2) at 500 lux and 31.4%, 19 mu W cm(-2) at 200 lux from a fluorescent lamp). A small array of DSCs with a joint active area of 16 cm(2) was then used to power machine learning on wireless nodes. The collection of 0.947 mJ or 2.72 x 10(15) photons is needed to compute one inference of a pre-trained artificial neural network for MNIST image classification in the employed set up. The inference accuracy of the network exceeded 90% for standard test images and 80% using camera-acquired printed MNIST-digits. Quantization of the neural network significantly reduced memory requirements with a less than 0.1% loss in accuracy compared to a full-precision network, making machine learning inferences on low-power microcontrollers possible. 152 J or 4.41 x 10(20) photons required for training and verification of an artificial neural network were harvested with 64 cm(2) photovoltaic area in less than 24 hours under 1000 lux illumination. Ambient light harvesters provide a new generation of self-powered and "smart" IoT devices powered through an energy source that is largely untapped.
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| 3. |
- Mogensen, Josefine, et al.
(författare)
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Indenofluorene-Extended Tetrathiafulvalene Scaffolds for Dye-Sensitized Solar Cells
- 2020
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1434-193X .- 1099-0690. ; 2020:38, s. 6127-6134
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Tidskriftsartikel (refereegranskat)abstract
- Indenofluorene‐extended tetrathiafulvalenes (IF‐TTFs) comprise a class of π‐conjugated sensitizers that exhibit strong absorptions in the visible region and two reversible one‐electron oxidations. Herein we present the synthesis and optical as well as redox properties of novel IF‐TTF donor‐acceptor scaffolds that were integrated in dye‐sensitized solar cells (DSCs) via anchoring of a carboxylic acid end‐group on the scaffolds to TiO2. Synthetically, the scaffolds were constructed by Sonogashira coupling reactions between an iodo‐functionalized IF‐TTF and an acceptor moeity containing a terminal alkyne. These very first IF‐TTF based candidates for DSCs exhibited high performances, in particular a dye incorporating a benzothiadiazole acceptor moiety, showing a conversion efficiency of 6.4 %. This result signals that IF‐TTF derivatives present a promising class of compounds for further structural modifications. Such modifications will benefit from the readiness of the iodo‐funcitonalized IF‐TTF building block to undergo Pd‐catalyzed coupling reactions.
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| 4. |
- Tanaka, Ellie, et al.
(författare)
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Synergy of co-sensitizers in a copper bipyridyl redox system for efficient and cost-effective dye-sensitized solar cells in solar and ambient light
- 2020
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 8:3, s. 1279-1287
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Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized solar cells (DSSCs) have a great potential to expand the area of photovoltaics towards portable or indoor applications. Since the dye is one of the most costly components in the device, it is always of interest to find ways to lower its associated cost. Here, we propose the co-sensitization technique as a simple and effective solution towards this aim. A less-expensive pi-A dye (5T) was mixed with a better-performing D-A-pi-A dye (XY1) to fabricate the co-sensitized devices (XY1 + 5T). The dyes were combined with a Cu-I/II(tmby)(2) (tmby = (4,4 ',6,6 '-tetramethyl-2,2 '-bipyridine)) electrolyte and tested at 1 sun and 0.1 sun conditions. The XY1 + 5T devices showed similar power conversion efficiency (PCE) to that of the XY1-only devices at 1 sun (avg. 9.1%), and superior PCE at 0.1 sun (avg. 9.4% vs. 8.6%). The charge transport behaviour in the devices was investigated through a combination of photophysical measurements, which revealed complementary effects of both dyes during device operation. The performance of XY1 + 5T at lower light intensity was further assessed using artificial fluorescent lighting, which marked a PCE as high as 29.2% at 1000 lux, among the highest reported. Finally, the cost of dye was estimated to be reduced by ca. 30% if an XY1-only device is replaced by XY1 + 5T with no loss in efficiency. The cost-performance is thus improved 1.4 times. Our findings will revalue the co-sensitization method as a means to address the challenges of DSSC commercialization.
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| 5. |
- Yuan, Lin, et al.
(författare)
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Four-Terminal Tandem Solar Cell with Dye-Sensitized and PbS Colloidal Quantum-Dot-Based Subcells
- 2020
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Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 3:4, s. 3157-3161
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Tidskriftsartikel (refereegranskat)abstract
- In this work, high-performance four-terminal solution-processed tandem solar cells were fabricated by using dye-sensitized solar cells (DSSCs) as top-cells and lead sulfide (PbS) colloidal quantum dot solar cells (CQDSCs) as bottom-cells. For dye-sensitized top-cells, three different dye combinations were used while the titanium dioxide (TiO2) scattering layer was removed to maximize the transmission. For the PbS bottom-cells, quantum dots with different sizes were compared. Over 12% power conversion efficiency has been achieved by using the XL dye mixture and 890 nm PbS QDs, which shows a significant efficiency enhancement when compared to single DSSC or CQDSC subcells.
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