| 1. |
- Meethal, Sruthi Meledath, et al.
(författare)
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Asymmetric dual species copper(II/I) electrolyte dye-sensitized solar cells with 35.6% efficiency under indoor light
- 2024
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 12:2, s. 1081-1093
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Tidskriftsartikel (refereegranskat)abstract
- Indoor photovoltaics (IPV) using dye-sensitized solar cells (DSCs) is one among the most promising ambient energy harvesting technologies used to realize self-powered Internet of Things (IoT), consumer electronics and portable devices. The emergence of new generation Cu(II/I) redox electrolytes used with co-sensitized organic dyes enables DSCs to realize higher open circuit photovoltages (Voc) and power conversion efficiencies (PCE) under indoor/ambient illumination. Even though Cu(II/I) electrolytes are promising candidates, the recombination of electrons from the conduction band and sub-bandgap states to the oxidized Cu(II) species and slower regeneration of Cu(II) at the counter electrode limit their performance. Taking inspiration from the asymmetric redox behaviour exhibited by the conventional iodide/triiodide electrolyte, which is efficient in inhibiting the undesirable recombination process, we introduced an alternative strategy of modifying the coordination environment of Cu(II) metal center using the 2,9-dimethyl-1,10-phenanthroline (dmp) ligand. The resulting dual species [Cu(II)(dmp)2Cl]+/[Cu(I)(dmp)2]+ electrolyte exhibited an improved lifetime both under full sun and indoor illumination and better regeneration at the counter electrode. Employing this asymmetric dual species Cu(II)/Cu(I) electrolyte with the co-sensitized D35:XY1 dyes, we realized a record PCE of 35.6% under 1000 lux warm white CFL illumination.
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| 2. |
- Hao, Yan, et al.
(författare)
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Peripheral Hole Acceptor Moieties on an Organic Dye Improve Dye-Sensitized Solar Cell Performance
- 2015
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Ingår i: Advanced Science. - : Wiley-Blackwell. - 2198-3844. ; 2:11
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Tidskriftsartikel (refereegranskat)abstract
- Investigation of charge transfer dynamics in dye-sensitized solar cells is of fundamental interest and the control of these dynamics is a key factor for developing more efficient solar cell devices. One possibility for attenuating losses through recombination between injected electrons and oxidized dye molecules is to move the positive charge further away from the metal oxide surface. For this purpose, a metal-free dye named E6 is developed, in which the chromophore core is tethered to two external triphenylamine (TPA) units. After photoinduced electron injection into TiO2, the remaining hole is rapidly transferred to a peripheral TPA unit. Electron-hole recombination is slowed down by 30% compared to a reference dye without peripheral TPA units. Furthermore, it is found that the added TPA moieties improve the electron blocking effect of the dye, retarding recombination of electrons from TiO2 to the cobalt-based electrolyte.
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| 3. |
- Cao, Yiming, et al.
(författare)
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11% efficiency solid-state dye-sensitized solar cells with copper(II/I) hole transport materials
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Solid-state dye-sensitized solar cells currently suffer from issues such as inadequate nanopore filling, low conductivity and crystallization of hole-transport materials infiltrated in the mesoscopic TiO2 scaffolds, leading to low performances. Here we report a record 11% stable solid-state dye-sensitized solar cell under standard air mass 1.5 global using a hole-transport material composed of a blend of [Cu (4,4',6,6'-tetramethyl-2,2'-bipyridine)2(bis(trifluoromethylsulfonyl)imide)2 and [Cu (4,4',6,6'-tetramethyl-2,2'-bipyridine)2](bis(trifluoromethylsulfonyl)imide). The amorphous Cu(II/I) conductors that conduct holes by rapid hopping infiltrated in a 6.5 mm-thick mesoscopic TiO2 scaffold are crucial for achieving such high efficiency. Using time-resolved laser photolysis, we determine the time constants for electron injection from the photoexcited sensitizers Y123 into the TiO2 and regeneration of the Y123 by Cu(I) to be 25 ps and 3.2 μs, respectively. Our work will foster the development of low-cost solid-state photovoltaic based on transition metal complexes as hole conductors.
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| 4. |
- Choi, Hyeon-Seo, et al.
(författare)
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Oriented Crystal Growth during Perovskite Surface Reconstruction
- 2022
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:45, s. 51149-51156
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Tidskriftsartikel (refereegranskat)abstract
- Surface passivation has become a key strategy for an improvement in power conversion efficiency (PCE) of perovskite solar cells (PSCs) since PSCs experienced a steep increase in PCE and reached a comparably matured point. Recently, surface passivation using a mixed salt of fluorinated alkyl ammonium iodide and formamidinium bromide demon-strated a remarkable improvement in both performance and stability, which can be tuned by the length of the alkyl chain. Nevertheless, the role of the alkyl chain in manipulating surface-limited crystal growth was not fully understood, preventing a further progress in interface control. In this study, we found that the length of the fluorine-substituted alkyl chain governed the crystal formation dynamics by manipulating surface tensions of different crystal orientations. The overall enhancement of the (001) plane, being the most favored, commonly resulted from the surface reformation of the perovskite film regardless of the chain length, while the highly oriented (001) over (111) was monitored with a particular chain length. The enhanced crystal orientation during surface recrystallization was responsible for the low trap density and thus effectively suppressed charge recombination at the interface, resulting in a considerable increase in open-circuit voltage and fill factor.
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| 5. |
- Freitag, Marina, et al.
(författare)
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High-efficiency dye-sensitized solar cells with molecular copper phenanthroline as solid hole conductor
- 2015
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 8:9, s. 2634-2637
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Tidskriftsartikel (refereegranskat)abstract
- Copper phenanthroline complexes in the solid phase can act as efficient molecular hole transporting material (HTM) for hybrid solar cells. We prepared solid-state dye-sensitized solar cells with the organic dye LEG4 and bis(2,9-dimethyl-1,10-phenanthroline)copper(I/II) (Cu(dmp)(2)) and achieved power conversion efficiencies of more than 8% under 1000 W m(-2) AM1.5G illumination, with open-circuit potentials of more than 1.0 V. The successful application of a copper-complex based HTM paves the way for low-cost and efficient hybrid solar cells, as well as for other opto-electronic devices.
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| 6. |
- Kim, Minjin, et al.
(författare)
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Conformal quantum dot-SnO2 layers as electron transporters for efficient perovskite solar cells
- 2022
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375:6578, s. 302-306
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Tidskriftsartikel (refereegranskat)abstract
- Improvements to perovskite solar cells (PSCs) have focused on increasing their power conversion efficiency (PCE) and operational stability and maintaining high performance upon scale-up to module sizes. We report that replacing the commonly used mesoporous-titanium dioxide electron transport layer (ETL) with a thin layer of polyacrylic acid-stabilized tin(IV) oxide quantum dots (paa-QD-SnO2) on the compact-titanium dioxide enhanced light capture and largely suppressed nonradiative recombination at the ETL-perovskite interface. The use of paa-QD-SnO2 as electron-selective contact enabled PSCs (0.08 square centimeters) with a PCE of 25.7% (certified 25.4%) and high operational stability and facilitated the scale-up of the PSCs to larger areas. PCEs of 23.3, 21.7, and 20.6% were achieved for PSCs with active areas of 1, 20, and 64 square centimeters, respectively.
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| 7. |
- Krishna, Anurag, et al.
(författare)
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Mitigating the Heterointerface Driven Instability in Perovskite Photovoltaics
- 2023
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Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 8:8, s. 3604-3613
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Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskites have thepotential to revolutionizethefield of photovoltaics, though limited stability has impeded commercialexploitation. The soft heterointerface between the perovskite andcharge-transporting layer is one of the major bottlenecks that limitsoperational stability. Here, we present rationally designed molecularmodulators that synergistically improve the stability of the & alpha;-FAPbI(3)-based perovskite solar cells while retaining power conversionefficiency (PCE) of 24.0% with a high open-circuit voltage (V (OC)) of & SIM;1.195 V. The interfacially modifiedphotovoltaic cells exhibit high operational stability, whereby thechampion device retains & SIM;88% of initial performance after 2000h of maximum power point tracking at 40 & DEG;C and 1 sun illumination.The molecular origins of such enhanced stability and device performanceare corroborated by multiscale characterization techniques and modeling,providing insights into the origins of performance and stability enhancements.
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| 8. |
- Krishna, Anurag, et al.
(författare)
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Nanoscale interfacial engineering enables highly stable and efficient perovskite photovoltaics
- 2021
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 14:10, s. 5552-5562
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Tidskriftsartikel (refereegranskat)abstract
- We present a facile molecular-level interface engineering strategy to augment the long-term operational and thermal stability of perovskite solar cells (PSCs) by tailoring the interface between the perovskite and hole transporting layer (HTL) with a multifunctional ligand 2,5-thiophenedicarboxylic acid. The solar cells exhibited high operational stability (maximum powering point tracking at one sun illumination) with a stabilized T-S80 (the time over which the device efficiency reduces to 80% after initial burn-in) of approximate to 5950 h at 40 degrees C and a stabilized power conversion efficiency (PCE) over 23%. The origin of high device stability and performance is correlated to the nano/sub-nanoscale molecular level interactions between ligand and perovskite layer, which is further corroborated by comprehensive multiscale characterization. These results provide insights into the modulation of the grain boundaries, local density of states, surface bandgap, and interfacial recombination. Chemical analysis of aged devices showed that molecular passivation suppresses interfacial ion diffusion and inhibits the photoinduced I-2 release that irreversibly degrades the perovskite. The interfacial engineering strategies enabled by multifunctional ligands can expedite the path towards stable PSCs.
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| 9. |
- Nonomura, Kazuteru, et al.
(författare)
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Blocking the Charge Recombination with Diiodide Radicals by TiO2 Compact Layer in Dye-Sensitized Solar Cells
- 2019
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Ingår i: Journal of the Electrochemical Society. - : ELECTROCHEMICAL SOC INC. - 0013-4651 .- 1945-7111. ; 166:9, s. B3203-B3208
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Tidskriftsartikel (refereegranskat)abstract
- The addition of a compact titanium dioxide (TiO2) layer between the fluorine-doped tin oxide (FTO) coated glass substrate and the mesoporous TiO2 layer in the dye-sensitized solar cell (DSC) based on the iodide/triiodide redox couple (I-/I-3(-)) is known to improve its current-voltage characteristics. The compact layer decreases the recombination of electrons extracted through the FTO layer with I-3(-) around the maximum power point. Furthermore, the short-circuit photocurrent was improved, which previously has been attributed to the improved light transmittance and/or better contact between TiO2 and FTO. Here, we demonstrate that the compact TiO2 layer has another beneficial effect: it blocks the reaction between charge carriers in the FTO and photogenerated diiodide radical species (I-2(-center dot)). Using photomodulated voltammetry, it is demonstrated that the cathodic photocurrent found at bare FTO electrodes is blocked by the addition of a compact TiO2 layer, while the anodic photocurrent due to reaction with I-2(-center dot) is maintained.
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| 10. |
- Pradhan, Sourava Chandra, et al.
(författare)
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Probing photovoltaic performance in copper electrolyte dye-sensitized solar cells of variable TiO2 particle size using comprehensive interfacial analysis
- 2022
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 10:10, s. 3929-3936
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Tidskriftsartikel (refereegranskat)abstract
- Copper-based metal complex redox mediators proved to be an efficient, futuristic electrolyte for dye-sensitized solar cell (DSC) applications addressing many critical issues of conventional iodide/triiodide electrolytes. However, copper redox mediators being bulkier than conventional iodine electrolytes impose movement restrictions contributing to unfavourable charge transfer processes. In the present manuscript, we analyzed the impact of TiO2 particle size (20 nm and 30 nm) on the photovoltaic parameters of DSCs using an organic D35 dye and an alternate copper redox mediator, Cu[(tmby)(2)](2+/1+). DSC photoanodes with 20 nm TiO2 particles realized a lower power conversion efficiency (PCE) of 6.32 +/- 0.07% in comparison to 7.36 +/- 0.12% efficiency achieved using DSCs made with 30 nm TiO2 particles. The improved PCE using 30 nm TiO2 particles is associated with the enhancement in short circuit current density (J(sc)), open-circuit potential (V-oc) and the fill factor (FF). Furthermore, comprehensive analysis of various charge transfer processes at discrete interfaces in these devices reveals collective enhancement in light-harvesting, dye regeneration and charge collection efficiency that ultimately contributed to achieving 16% improvement in PCE using 30 nm TiO2 particles.
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