| 1. |
- Feng, Guitao, et al.
(författare)
-
“Double-Cable” Conjugated Polymers with Linear Backbone toward High Quantum Efficiencies in Single-Component Polymer Solar Cells
- 2017
-
Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 139:51, s. 18647-18656
-
Tidskriftsartikel (refereegranskat)abstract
- A series of "double-cable" conjugated polymers were developed for application in efficient single-component polymer solar cells, in which high quantum efficiencies could be achieved due to the optimized nanophase separation between donor and acceptor parts. The new double-cable polymers contain electron-donating poly(benzodithiophene) (BDT) as linear conjugated backbone for hole transport and pendant electron-deficient perylene bisimide (PBI) units for electron transport, connected via a dodecyl linker. Sulfur and fluorine substituents were introduced to tune the energy levels and crystallinity of the conjugated polymers. The double-cable polymers adopt a "face-on" orientation in which the conjugated BDT backbone and the pendant PBI units have a preferential pi-pi stacking direction perpendicular to the substrate, favorable for interchain charge transport normal to the plane. The linear conjugated backbone acts as a scaffold for the crystallization of the PBI groups, to provide a double-cable nanophase separation of donor and acceptor phases. The optimized nanophase separation enables efficient exciton dissociation as well as charge transport as evidenced from the high-up to 80%-internal quantum efficiency for photon-to-electron conversion. In single-component organic solar cells, the double-cable polymers provide power conversion efficiency up to 4.18%. This is one of the highest performances in single-component organic solar cells. The nanophase-separated design can likely be used to achieve high-performance single-component organic solar cells.
|
|
| 2. |
- Li, Weiwei, et al.
(författare)
-
Tailoring side chains of low band gap polymers for high efficiency polymer solar cells
- 2010
-
Ingår i: Polymer. - : Elsevier Science B.V., Amsterdam.. - 0032-3861 .- 1873-2291. ; 51:14, s. 3031-3038
-
Tidskriftsartikel (refereegranskat)abstract
- High efficiency organic solar cells (OSCs) require conjugated polymers with a low band gap, broad absorption in visible and IR region, high carrier mobility, and relatively high molecular weight as p-type donor materials. Flexible side chains on the rigid polymer backbone are crucial for the solubility of conjugated polymers. In this work, four polymers with the main chain structure of fluorene-thiophene-benzothiadiazole-thiophene and flexible side chains located on fluorene, thiophene, and benzothiadiazole moiety, respectively, have been synthesized by Suzuki-Miyaura-Schluter polycondensation. Photovoltaic device measurements with a device configuration of ITO/polymer:PC71BM blends/LiF/Al show that P1 carrying octyloxy chains on benzothiadiazole rings gives the best performance, with a power conversion efficiency of 3.1%.
|
|
| 3. |
- Zhang, Ben, et al.
(författare)
-
Rapid solidification for green-solvent-processed large-area organic solar modules with >16% efficiency
- 2024
-
Ingår i: Energy & Environmental Science. - : ROYAL SOC CHEMISTRY. - 1754-5692 .- 1754-5706.
-
Tidskriftsartikel (refereegranskat)abstract
- Enabling green-solvent-processed large-area organic solar cells (OSCs) is of great significance to their industrialization. However, precisely controlling the temperature-dependent fluid mechanics and evaporation behavior of green solvents with high-boiling points is challenging. Controlling these parameters is essential to prevent the non-uniform distribution of active layer components and severe molecule aggregation, which collectively degrade the power conversion efficiency (PCE) of large-scale devices. In this study, we revealed that the temperature gradient distribution across a wet film is the root of the notorious Marangoni effect, which leads to the formation of a severely non-uniform active layer on a large scale. Thus, a rapid solidification strategy was proposed to accelerate the evaporation of toluene, a green solvent, at room temperature. This strategy simultaneously inhibits the Marangoni effect and suppresses molecular aggregation in the wet film, allowing the formation of a nano-scale phase separation active layer with uniform morphology. The resultant toluene-processed 15.64-cm2 large-area OSC module achieves an outstanding PCE of 16.03% (certified: 15.69%), which represents the highest reported PCE of green-solvent-processed OSC modules. Notably, this strategy also exhibits a weak scale dependence on the PCE, and we successfully achieved a state-of-the-art PCE of 14.45% for a 72.00-cm2 OSC module. A rapid solidification strategy was developed for simultaneously avoiding the Marangoni effect and suppressing molecular aggregation. The resultant 15.64 cm2 large-area OSC module exhibited a record power conversion efficiency of 16.03%.
|
|
| 4. |
- Chen, Haiyang, et al.
(författare)
-
Heterogeneous Nucleating Agent for High-Boiling-Point Nonhalogenated Solvent-Processed Organic Solar Cells and Modules
- 2024
-
Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095.
-
Tidskriftsartikel (refereegranskat)abstract
- High-boiling-point nonhalogenated solvents are superior solvents to produce large-area organic solar cells (OSCs) in industry because of their wide processing window and low toxicity; while, these solvents with slow evaporation kinetics will lead excessive aggregation of state-of-the-art small molecule acceptors (e.g. L8-BO), delivering serious efficiency losses. Here, a heterogeneous nucleating agent strategy is developed by grafting oligo (ethylene glycol) side-chains on L8-BO (BTO-BO). The formation energy of the obtained BTO-BO; while, changing from liquid in a solvent to a crystalline phase, is lower than that of L8-BO irrespective of the solvent type. When BTO-BO is added as the third component into the active layer (e.g. PM6:L8-BO), it easily assembles to form numerous seed crystals, which serve as nucleation sites to trigger heterogeneous nucleation and increase nucleation density of L8-BO through strong hydrogen bonding interactions even in high-boiling-point nonhalogenated solvents. Therefore, it can effectively suppress excessive aggregation during growth, achieving ideal phase-separation active layer with small domain sizes and high crystallinity. The resultant toluene-processed OSCs exhibit a record power conversion efficiency (PCE) of 19.42% (certificated 19.12%) with excellent operational stability. The strategy also has superior advantages in large-scale devices, showing a 15.03-cm2 module with a record PCE of 16.35% (certificated 15.97%). The heterogeneous nucleating agent (BTO-BO) is developed to suppress the excessive aggregation of L8-BO in high-boiling-point nonhalogenated solvents processing, achieving the active layer with high crystallinity and nano-scaled phase separation morphology. The resultant OSCs achieve record power conversion efficiencies of 19.42% (0.062-cm2) and 16.35% (15. 03-cm2) with excellent operational stabilities. image
|
|
| 5. |
- Chen, Weiwei, et al.
(författare)
-
Lane departure warning systems and lane line detection methods based on image processing and semantic segmentation : A review
- 2020
-
Ingår i: Journal of Traffic and Transportation Engineering (English Edition). - : Elsevier BV. - 2095-7564. ; 7:6, s. 748-774
-
Forskningsöversikt (refereegranskat)abstract
- Recently, the development and application of lane line departure warning systems have been in the market. For any of the systems, the key part of lane line tracking, lane line identification, or lane line departure warning is whether it can accurately and quickly detect lane lines. Since 1990s, they have been studied and implemented for the situations defined by the good viewing conditions and the clear lane markings on road. After then, the accuracy for particular situations, the robustness for a wide range of scenarios, time efficiency and integration into higher-order tasks define visual lane line detection and tracking as a continuing research subject. At present, these kinds of lane marking line detection methods based on machine vision and image processing can be divided into two categories: the traditional image processing and semantic segmentation (includes deep learning) methods. The former mainly involves feature-based and model-based steps, and which can be classified into similarity- and discontinuity-based ones; and the model-based step includes different parametric straight line, curve or pattern models. The semantic segmentation includes different machine learning, neural network and deep learning methods, which is the new trend for the research and application of lane line departure warning systems. This paper describes and analyzes the lane line departure warning systems, image processing algorithms and semantic segmentation methods for lane line detection.
|
|
| 6. |
- Du, Chun, et al.
(författare)
-
9-Alkylidene-9H-Fluorene-Containing Polymer for High-Efficiency Polymer Solar Cells
- 2011
-
Ingår i: Macromolecules. - : American Chemical Society. - 0024-9297 .- 1520-5835. ; 44:19, s. 7617-7624
-
Tidskriftsartikel (refereegranskat)abstract
- A novel donor-acceptor copolymer containing 9-alkylidene-9H-fluorene unit in the main chain, poly[9-(1-hexylheptylidene)-2,7-fluorene-alt-5, 5-(4,7-di-2-thienyl-5,6-dialkoxy-2,1,3-benzothiadiazole)] (PAFDTBT), has been synthesized and evaluated in bulk heterojunction polymer solar cells (BHJ PSCs). The polymer possesses a low band gap of 1.84 eV, a low-lying HOMO energy level (5.32 eV), and excellent solubility in common organic solvents. PSCs based on PAFDTBT and (6,6)-phenyl-C(71)-butyric add methyl ester (PC(71)BM) demonstrate a power conversion efficiency (PCE) of 6.2% with a high fill factor (FF) of 0.70, which indicates that 9-alkylidene-9H-fluorene can be a very useful building block for constructing narrow band gap conjugated polymers for high-efficiency BHJ PSCs.
|
|
| 7. |
- Guo, Yiting, et al.
(författare)
-
Effect of Side Groups on the Photovoltaic Performance Based on Porphyrin-Perylene Bisimide Electron Acceptors
- 2018
-
Ingår i: ACS Applied Materials and Interfaces. - : AMER CHEMICAL SOC. - 1944-8244 .- 1944-8252. ; 10:38, s. 32454-32461
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we developed four porphyrin-based small molecular electron acceptors for non-fullerene organic solar cells, in which different side groups attached to the porphyrin core were selected in order to achieve optimized performance. The molecules contain porphyrin as the core, perylene bisimides as end groups, and the ethynyl unit as the linker. Four side groups, from 2,6-di(dodecyloxy)phenyl to (2-ethylhexyl)thiophen-2-yl, pentadecan-7-yl, and 3,5-di(dodecyloxy)phenyl unit, were applied into the electron acceptors. The new molecules exhibit broad absorption spectra from 300 to 900 nm and high molar extinction coefficients. The molecules as electron acceptors were applied into organic solar cells, showing increased power conversion efficiencies from 1.84 to 5.34%. We employed several techniques, including photoluminescence spectra, electroluminescence spectra, atomic force microscopy, and grazing-incidence wide-angle X-ray to probe the blends to find the effects of the side groups on the photovoltaic properties. We found that the electron acceptors with 2,6-di(dodecyloxy)phenyl units show high-lying frontier energy levels, good crystalline properties, and low nonradiative recombination loss, resulting in possible large phase separation and low energy loss, which is responsible for the low performance. Our results provide a detailed study about the side groups of non-fullerene materials, demonstrating that porphyrin can be used to design electron acceptors toward near-infrared absorption.
|
|
| 8. |
- Huang, Jianqing, et al.
(författare)
-
A detailed study on the micro-explosion of burning iron particles in hot oxidizing environments
- 2022
-
Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180. ; 238
-
Tidskriftsartikel (refereegranskat)abstract
- As a promising carbon-free fuel, iron powder can directly combust with air and has great potential to provide clean and high-grad heat for various applications. The combustion characteristics of iron particles are of great significance for developing iron combustion model, designing efficient combustor, and optimizing combustion technologies. In this work, the micro-explosion behavior of burning iron particles was experimentally investigated based on optical diagnostics. With two high-speed cameras operating at 10,000 frames per second, the three-dimensional (3D) motion and mean surface temperature of burning iron particles during the micro-explosion process were measured using the stereo imaging technique and two-color pyrometry, respectively. The probability of micro-explosions in different oxidizing environments were statistically studied. Three distinct micro-explosion modes have been observed. The results showed that the micro-explosion of burning iron particles heavily depended on oxygen concentration. The micro-explosion would slightly reduce the particle surface temperature by 30–70 K within 0.5 ms, since a lot of smaller fragments were produced. In addition, the 3D velocity of most fragments would sharply increase to 2–6 times within 0.2 ms after the micro-explosion occurred. Regarding the mechanism of the micro-explosion, three types of potential gas sources inside the particle were discussed. The sharp gradients of gas temperature and oxygen concentration may facilitate the rapid increase of the internal pressure in the particle, which eventually causes the micro-explosion.
|
|
| 9. |
- Huang, Jianqing, et al.
(författare)
-
Clustering-based particle detection method for digital holography to detect the three-dimensional location and in-plane size of particles
- 2021
-
Ingår i: Measurement Science and Technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 32:5
-
Tidskriftsartikel (refereegranskat)abstract
- Digital holography (DH) has been extensively applied in particle field measurements due to its promising ability to simultaneously provide the three-dimensional location and in-plane size of particles. Particle detection methods are crucial in hologram data processing to determine particle size and particle in-focus depth, which directly affect the measurement accuracy and robustness of DH. In this work, inspired by clustering algorithms, a new clustering-based particle detection (CBPD) method was proposed for DH. To the best of our knowledge this is the first time that clustering algorithms have been applied in processing holograms for particle detection. The results of both simulations and experiments confirmed the feasibility of our proposed method. This data-driven method features automatic recognition of particles, particle edges and background, and accurate separation of overlapping particles. Compared with seven conventional particle detection methods, the CBPD method has improved accuracy in measuring particle positions and displacements.
|
|
| 10. |
- Huang, Jianqing, et al.
(författare)
-
Quantification of the size, 3D location and velocity of burning iron particles in premixed methane flames using high-speed digital in-line holography
- 2021
-
Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180. ; 230
-
Tidskriftsartikel (refereegranskat)abstract
- Due to its low emission and high energy density, iron powder has been proposed as a promising recyclable metal fuel for a future low-carbon society. The comprehensive understanding of combustion behavior of iron particles is crucial for studying fundamental mechanisms, developing suitable combustion technologies, and designing efficient iron powder combustor. In this work, iron particles are combusted in a modified Bunsen burner with a stable metal powder supplying system. As a versatile three-dimensional (3D) imaging technique, high-speed digital in-line holography (DIH) is employed to reconstruct the 3D particle field and simultaneously quantify the size, 3D location and velocity of burning iron particles. The statistical results of three cases with oxygen volume fraction varying from 24% to 40% are obtained and compared at different heights above the burner. Along the height, some typical features of the burning iron particles were observed. The violent combustion of iron particles accelerates the ejection of the particles radially outward from the central region of the flame, resulting in non-uniform spatial distribution of the particles and reducing the particle number density in the measurement volume. Such trend is enhanced with increased oxygen concentration. Besides, the observed particle size enlarged as the height increases, which validates the swelling phenomenon of iron particle oxidation. The results demonstrate that DIH is a powerful tool for in-situ, quantitative characterization of particle dynamics in flames.
|
|
