| 11. |
- Wang, Linqin, et al.
(författare)
-
A crosslinked polymer as dopant-free hole-transport material for efficient n-i-p type perovskite solar cells
- 2021
-
Ingår i: Journal of Energy Chemistry. - : Elsevier BV. - 2095-4956 .- 2096-885X. ; 55, s. 211-218
-
Tidskriftsartikel (refereegranskat)abstract
- A new crosslinked polymer, called P65, with appropriate photo-electrochemical, opto-electronic, and thermal properties, has been designed and synthesized as an efficient, dopant-free, hole-transport material (HTM) for n-i-p type planar perovskite solar cells (PSCs). P65 is obtained from a low-cost and easily synthesized spiro[fluorene-9,9′-xanthene]-3′,6′-diol (SFX-OH)-based monomer X65 through a free-radical polymerization reaction. The combination of a three-dimensional (3D) SFX core unit, hole-transport methoxydiphenylamine group, and crosslinked polyvinyl network provides P65 with good solubility and excellent film-forming properties. By employing P65 as a dopant-free hole-transport layer in conventional n-i-p type PSCs, a power conversion efficiency (PCE) of up to 17.7% is achieved. To the best of our knowledge, this is the first time a 3D, crosslinked, polymeric dopant-free HTM has been reported for use in conventional n-i-p type PSCs. This study provides a new strategy for the future development of a 3D crosslinked polymeric dopant-free HTM with a simple synthetic route and low-cost for commercial, large-scale applications in future PSCs.
|
|
| 12. |
- Wang, Linqin, et al.
(författare)
-
Design and synthesis of dopant-free organic hole-transport materials for perovskite solar cells
- 2018
-
Ingår i: Chemical Communications. - : ROYAL SOC CHEMISTRY. - 1359-7345 .- 1364-548X. ; 54:69, s. 9571-9574
-
Tidskriftsartikel (refereegranskat)abstract
- Two novel dopant-free hole-transport materials (HTMs) with spiro[dibenzo[c,h]xanthene-7,9-fluorene] (SDBXF) skeletons were prepared via facile synthesis routes. A power conversion efficiency of 15.9% in perovskite solar cells is attained by using one HTM without dopants, which is much higher than undoped Spiro-OMeTAD-based devices (10.8%). The crystal structures of both new HTMs were systematically investigated to reveal the reasons behind such differences in performance and to indicate the design principles of more advanced HTMs.
|
|
| 13. |
- Yang, Xia, et al.
(författare)
-
Integrated assessment of indoor and outdoor ventilation in street canyons with naturally-ventilated buildings by various ventilation indexes
- 2020
-
Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 169
-
Tidskriftsartikel (refereegranskat)abstract
- The integrated assessments of indoor and outdoor ventilation are still rare so far. As a novelty, this paper aims to quantify the influence of street aspect ratios (building height/street width, H/W = 0.5–5) and window sizes (1 m × 1 m, 1.5 m × 1.5 m) on indoor-outdoor ventilation in two-dimensional streets with single-sided naturally-ventilated buildings. Numerical simulations with RNG k-ε model are validated against experimental data and the grid independence are tested as well. Air change rates per hour (ACH, h−1) are adopted for assessing indoor-outdoor ventilation by mean flows (ACHmean) and turbulent fluctuations (ACHturb) respectively. Age of air(τ), purging flow rate (PFR) and its corresponding ACHPFR are used to evaluate overall ventilation capacities.Shallower streets experience better indoor-outdoor ventilation. Outdoor ACHPFR drop from 14.69 to 17.55 h−1 to 3.96–3.97 h−1 as H/W rises from 0.5 to 3. In extremely deep canyon (H/W = 5), two-counter-rotating vortices produce much smaller velocity at low-level regions (U/Uref~10−3-10−5), resulting in small ACHPFR for outdoor (~0.76–0.91 h−1) and indoor in 1–13th floors (~0.03–0.61 h−1). When H/W = 0.5–1, leeward 5–6th floors experience smaller ACHPFR(e.g.~1.13–1.40 h−1 as H/W = 1) than the other floors (e.g. ~1.54–9.52 h−1 as H/W = 1). Particularly, as H/W = 2–3, leeward-side indoor ACHPFR in the middle floors (except the first and top two floors) are nearly constants (~1.02–1.69 h−1) and much smaller than windward-side ACHPFR(~1.41–4.35 h−1) which increase toward upper floors. Besides, the smaller window size reduces indoor ACHPFR by 19.38%~88.28%, but hardly influences outdoor ventilation. Moreover, both outdoor and indoor ACHPFR are greater than ACHmean but smaller than ACHmean + ACHturb. Although further investigations are still required, this paper provides an insight and scientific foundation on integrated indoor-outdoor ventilation evaluation with various effective ventilation indexes.
|
|
| 14. |
- Zhang, Biaobiao, et al.
(författare)
-
Defective and "c-Disordered" Hortensia-like Layered MnOx as an Efficient Electrocatalyst for Water Oxidation at Neutral pH
- 2017
-
Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 7:9, s. 6311-6322
-
Tidskriftsartikel (refereegranskat)abstract
- The development of a highly active manganese-based water oxidation catalyst in the design of an ideal artificial photosynthetic device operating under neutral pH conditions remains a great challenge, due to the instability of pivotal Mn3+ intermediates. We report here defective and "c-disordered" layered manganese oxides (MnOx-300) formed on a fluorine-doped tin oxide electrode by constant anodic potential deposition and subsequent annealing, with a catalytic onset (0.25 mA/cm(2)) at an overpotential (eta) of 280 mV and a benchmark catalytic current density of 1.0 mA/cm(2) at an overpotential (eta) of 330 mV under neutral pH (1 M potassium phosphate). Steady current density above 8.2 mA/cm(2) was obtained during the electrolysis at 1.4 V versus the normal hydrogen electrode for 20 h. Insightful studies showed that the main contributing factors for the observed high activity of MnOx-300 are (i) a defective and randomly stacked layered structure, (ii) an increased degree of Jahn-Teller distorted Mn3+ in the MnO6 octahedral sheets, (iii) effective stabilization of Mn3+, (iv) a high surface area, and (v) improved electrical conductivity. These results demonstrate that manganese oxides as structural and functional models of an oxygen-evolving complex (OEC) in photosystem II are promising catalysts for water oxidation in addition to Ni/Co-based oxides/hydroxides.
|
|
| 15. |
- Zhang, Biaobiao, et al.
(författare)
-
Electrocatalytic Water Oxidation Promoted by 3 D Nanoarchitectured Turbostratic Δ-MnOx on Carbon Nanotubes
- 2017
-
Ingår i: ChemSusChem. - : Wiley-VCH Verlag. - 1864-5631 .- 1864-564X. ; 10:22, s. 4472-4478
-
Tidskriftsartikel (refereegranskat)abstract
- The development of manganese-based water oxidation electrocatalysts is desirable for the production of solar fuels, as manganese is earth-abundant, inexpensive, non-toxic, and has been employed by the Photosystem II in nature for a billion years. Herein, we directly constructed a 3 D nanoarchitectured turbostratic δ-MnOx on carbon nanotube-modified nickel foam (MnOx/CNT/NF) by electrodeposition and a subsequent annealing process. The MnOx/CNT/NF electrode gives a benchmark catalytic current density (10 mA cm−2) at an overpotential (η) of 270 mV under alkaline conditions. A steady current density of 19 mA cm−2 is obtained during electrolysis at 1.53 V for 1.0 h. To the best of our knowledge, this work represents the most efficient manganese-oxide-based water oxidation electrode and demonstrates that manganese oxides, as a structural and functional model of oxygen-evolving complex (OEC) in Photosystem II, can also become comparable to those of most Ni- and Co-based catalysts.
|
|
| 16. |
- Zhang, Wei, et al.
(författare)
-
The Central Role of Ligand Conjugation for Properties of Coordination Complexes as Hole-Transport Materials in Perovskite Solar Cells
- 2019
-
Ingår i: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 2:9, s. 6768-6779
-
Tidskriftsartikel (refereegranskat)abstract
- Two zinc-based coordination complexes Y3 and Y4 have been synthesized and characterized, and their performance as hole-transport materials (HTMs) for perovskite solar cells (PSCs) has been investigated. The complex Y3 contains two separate ligands, and the molecular structure can be seen as a disconnected porphyrin ring. On the other hand, Y4 consists of a porphyrin core and therefore is a more extended conjugated system as compared to Y3. The optical and redox properties of the two different molecular complexes are comparable. However, the hole mobility and conductivity of Y4 as macroscopic material are remarkably higher than that of Y3. Furthermore, when employed as hole-transport materials in perovskite solar cells, cells containing Y4 show a power conversion efficiency (PCE) of 16.05%, comparable to the Spiro-OMeTAD-based solar cells with an efficiency around 17.08%. In contrast, solar cells based on Y3 show a negligible efficiency of about 0.01%. The difference in performance of Y3 and Y4 is analyzed and can be attributed to the difference in packing of the nonplanar and planar building blocks in the corresponding materials.
|
|
| 17. |
- Zhang, Xin, et al.
(författare)
-
Minimizing the Interface-Driven Losses in Inverted Perovskite Solar Cells and Modules
- 2023
-
Ingår i: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 8:6, s. 2532-2542
-
Tidskriftsartikel (refereegranskat)abstract
- The inverted p-i-n perovskite solar cells hold high promise for scale-up toward commercialization. However, the interfaces between the perovskite and the charge transport layers contribute to major power conversion efficiency (PCE) loss and instability. Here, we use a single material of 2-thiopheneethylammonium chloride (TEACl) to molecularly engineer both the interface between the perovskite and fullerene-C60 electron transport layer and the buried interface between the perovskite and NiOx-based hole transport layer. The dual interface modification results in optimized band alignment, suppressed nonradiative recombination, and improved interfacial contact. A PCE of 24.3% is demonstrated, with open-circuit voltage (Voc) and fill factor (FF) of 1.17 V and 84.6%, respectively. The unencapsulated device retains >97.0% of the initial performance after 1000 h of maximum power point tracking under illumination. Moreover, a PCE of 22.6% and a remarkable FF of 82.4% are obtained for a mini-module with an active area of 3.63 cm2.
|
|
| 18. |
- Abramoff, Rose Z., et al.
(författare)
-
How much carbon can be added to soil by sorption?
- 2021
-
Ingår i: Biogeochemistry. - : Springer Nature. - 0168-2563 .- 1573-515X. ; 152:2-3, s. 127-142
-
Tidskriftsartikel (refereegranskat)abstract
- Quantifying the upper limit of stable soil carbon storage is essential for guiding policies to increase soil carbon storage. One pool of carbon considered particularly stable across climate zones and soil types is formed when dissolved organic carbon sorbs to minerals. We quantified, for the first time, the potential of mineral soils to sorb additional dissolved organic carbon (DOC) for six soil orders. We compiled 402 laboratory sorption experiments to estimate the additional DOC sorption potential, that is the potential of excess DOC sorption in addition to the existing background level already sorbed in each soil sample. We estimated this potential using gridded climate and soil geochemical variables within a machine learning model. We find that mid- and low-latitude soils and subsoils have a greater capacity to store DOC by sorption compared to high-latitude soils and topsoils. The global additional DOC sorption potential for six soil orders is estimated to be 107 ± 13 Pg C to 1 m depth. If this potential was realized, it would represent a 7% increase in the existing total carbon stock.
|
|
| 19. |
- Chen, Haorui, et al.
(författare)
-
Forecasting the human and climate impacts on groundwater resources in the irrigated agricultural region of North China Plain
- 2023
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 37:3
-
Tidskriftsartikel (refereegranskat)abstract
- Climate change has caused significant impacts on water resource redistribution around the world and posed a great threat in the last several decades due to intensive human activities. The impacts of human water use and management on regional water resources remain unclear as they are intertwined with the impacts of climate change. In this study, we disentangled the impact of climate-induced human activities on groundwater resources in a typical region of the semi-arid North China Plain based on a process-oriented groundwater modelling approach accounting for climate-human-groundwater interactions. We found that the climate-induced human effect is amplified in water resources management ('amplifying effect') for our study region under future climate scenarios. We specifically derived a tipping point for annual precipitation of 350 mm, below which the climate-induced human activities on groundwater withdrawal will cause significant 'amplifying effect' on groundwater depletion. Furthermore, we explored the different pumping scenarios under various climate conditions and investigated the pumping thresholds, which the pumping amount should not exceed (4 x 10(7) m(3)) in order to control future groundwater level depletion. Our results highlight that it is critical to implement adaptive water use practices, such as water-saving irrigation technologies in the semi-arid regions, in order to mitigate the negative impacts of groundwater overexploitation, particularly when annual precipitation is anomalously low.
|
|
| 20. |
- Chen, Jiajia, et al.
(författare)
-
Characterization of Longitudinal Thermal Conductivity of Graphene Film
- 2021
-
Ingår i: 2021 22nd International Conference on Electronic Packaging Technology, ICEPT 2021.
-
Konferensbidrag (refereegranskat)abstract
- The chase of high performance by chip manufacturers has greatly increased the power consumption of integrated circuits, which brings great challenges to the heat dissipation of electronics systems. It has also slowed down following up of the Moore's Law, and it is expected to hit the wall soon [1]. Graphene film with high in-plane thermal conductivity is one of the key materials to make it possible for electronics industry to continue to follow the Moore's Law. However, there are few studies focusing on the longitudinal thermal conductivity of graphene films. The purpose of this study is to investigate the longitudinal thermal conductivity of graphene films according to ASTM D5470 [2]. The results show that the longitudinal thermal conductivity of the pressed graphene film is greater than that of the unpressurized graphene film. The longitudinal thermal conductivity is 10.6 W/m· K for the unpressurized graphene film and 20.6 W/m· K for the pressed graphene film.
|
|
