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Over 14% Efficiency Nonfullerene All-Small-Molecule Organic Solar Cells Enabled by Improving the Ordering of Molecular Donor via Side-Chains Engineering
摘要： Improving the short current density (Jsc) is a big challenge for gaining highly efficient nonfullerene all-small-molecule organic solar cells (NFASM-OSCs). Herein, a novel small molecular donor, BT-2F which is derived from previously reported BTEC-2F, was designed and synthesized. The shortened alkyl-chains with higher regularity endow BT-2F with more ordered packing arrangement and more compact lamellar stacking as evidenced by the characterization of differential scanning calorimetry and grazing incidence X-ray diffraction. By blending BT-2F with Y6 or N3, BT-2F based devices showed impressive power conversion efficiencies (PCEs) of 13.80% and 14.09% respectively, much higher than the reported PCE of 13.34% for BTEC-2F:Y6. Besides, the efficiency of 14.09% is also among the highest PCE value reported so far for NFASM-OSCs. The distinctly improved Jsc devoted major efforts to enhancing the PCE values, meanwhile both BT-2F:Y6 and BT-2F:N3 still keep the high fill factors over 70%, which are ascribed to the good balance between high crystallinity and proper phase separation.
关键词： Morphology control,Crystallinity,Highly efficient nonfullerene organic solar cells,Molecular packing arrangement,Molecule design
更新于2025-09-23 15:19:57
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Experimental investigation on the machining characteristics of fixed-free abrasive combined wire sawing PV polycrystalline silicon solar cell
摘要： At present, the fixed abrasive wire sawing (FAWS) technology is gradually used in the photovoltaic industry to cut polycrystalline silicon slices. However, there are obvious directional wire marks, parallel grooves, and amorphous silicon layer on the surface of the slices formed by the FAWS, which leads to a high optic reflectivity of the textured surface obtained after the mature acid etching texturization technology. So the slices cannot meet the requirements of the photovoltaic cell. In the paper, a novel fixed-free abrasive combined wire sawing (FFACWS) technology for cutting PV polycrystalline silicon is presented to solve this problem, by adding loose SiC abrasives to cooling lubricant during the fixed abrasive wire sawing. A single-factor and orthogonal experimental study on sawing characteristics was carried out. The effect of size and mass fraction of SiC abrasives in the slurry, workpiece feed speed and wire speed on the surface morphology, roughness, and kerf loss were studied. The results show that within the range of the processing parameters in the paper studied, the obvious wire marks, parallel grooves, and ductile layers on the surface of the slices can be removed by the FFACWS. The surface roughness of the slices along the wire movement direction and the workpiece feed direction increases with the increase of the mass fraction of SiC abrasives in the slurry and workpiece feed speed and it decreases with the increase of wire speed. But the effect of the size of SiC abrasives is related to the matching of the protruding height of the fixed abrasives on the wire surface along the workpiece feed direction. In the wire movement direction, it increases with the size of SiC abrasives. The kerf loss increases with the increase of size and mass fraction of SiC abrasives in the slurry and the wire speed but has little effect with the change of workpiece feed speed.
关键词： Fixed-free abrasive combined wire sawing,Surface morphology,Surface roughness,Kerf loss,Photovoltaic polycrystalline silicon
更新于2025-09-23 15:19:57
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Morphological characteristics of nanoholes induced by single-shot femtosecond laser ablation of borates and aluminate silicates
摘要： Single-shot femtosecond laser ablation experiments with linearly and circularly polarized light were conducted in order to investigate the morphological characteristics of surface nanostructures in lithium borate crystals and glasses, a strontium borate crystal, lanthanide containing borate crystals, and aluminate silicate crystals: Li2B4O7 (LTB) and LiB3O5 (LBO) crystals and Li2O?2B2O3 (LTB) and Li2O?3B2O3 (LBO) glasses; SrB4O7 (SBO) crystal; Li6Gd(BO3)3 (LGB) and LaSc3(BO3)4 (LSB) crystals; and Ca2Al2SiO7 (CAS) and CaSrAl2SiO7 (CSAS) crystals. In the present study, the material and laser polarization dependance of the morphology of nanoholes was examined in these crystals and glasses. A single nanohole or two holes (a primary hole and a secondary hole) were observed in the borate and aluminate silicate crystals. The size of the nanohole is not restricted by the diffraction limit but instead is dependent on the laser fluence and the materials. It is suggested that the formation of these secondary nanoholes in the studied crystals is attributed to a spontaneous reshaping of the incoming Gaussian pulse into a Gaussian–Bessel pulse. In the LTB and LBO crystals, nanoholes (both primary and secondary holes) with subwavelength sides exhibit a quadrilateral (approximately square or rectangular) morphology, regardless of linear or circular polarization. The sides of the quadrilateral nanoholes lie approximately in the {h h 0} planes on the LTB crystal and in the ({h 0 0} and {0 0 l}) planes on the LBO crystal. We found that the nanohole morphology did not reflect the spatial distribution of the laser intensity. These phenomena were the first observations on the anisotropic morphology of nanoholes. These morphologies do not correspond to the circular symmetric pattern of the Gaussian intensity distribution of the incoming laser beam. This is contrary to the expectations based on the generally accepted laser ablation mechanism. The quadrilateral nanoholes could be an inherent morphology in the LTB and LBO crystals. The morphology of the network structure in their quadrilateral holes in the LTB and LBO crystals is considered to reflect the continuous BO3 and/or BO4 3? 5? respective tetragonal or orthorhombic unit cells, in which self-tapped excitons are formed in an initial process under multiphoton excitation. In contrast, the SBO, LGB, LSB, CAS, and CSAS crystals and the LTB and LBO glasses exhibit circular nanoholes with subwavelength diameters independent of the laser polarization, the structure, or the composition. The isotropic morphology of nanoholes in these samples reflects the circular pattern of the Gaussian intensity profile of the focused laser beam.
关键词： borate,single pulse,aluminosilicate,scanning electron microscopy,crystal structure,nanohole morphology,femtosecond laser ablation,nanostructuring
更新于2025-09-23 15:19:57
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Significance of Dopant/Component Miscibility to Efficient N-Doping in Polymer Solar Cells
摘要： The uncertain dopant location in the bulk heterojunction (BHJ) film hinders the wide application of molecular doping in polymer solar cells (PSCs) as is in other organic devices. It is known that the interaction between dopant and component governs the dopant distribution in the BHJ film, and thus largely controls the effectiveness of molecular doping. After excluding the strong dopant/component interaction by forming the charge-transfer complex in solution, we estimate the dopant/component miscibility by calculating the difference of Hansen’s total solubility parameters (δi-Hansen) and prove its correctness by contact angle measurements, and two model systems of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophe-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl -5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione))] (PBDB)/poly{[N,N’-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5’-(2,2’-bithiophene)} (N2200) and poly[4,8-bis(5-(2-ethylhexyl)-thiophene-2-yl)benzo[1,2-b;4,5-b’]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl]] (PCE10)/N2200 are selected to reveal the miscibility-photovoltaic performance relations. Only the material combination with large δi-Hansen between n-dopant (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl) phenyl) dimethylamine (N-DMBI) and the donor polymer achieves enhanced photovoltaic performance. After that, we examine the doped morphology of polymer blends. Since the polymers’ crystallizations are negatively affected by N-DMBI addition, we ensure the significance of n-doping on the enhanced device performance. Besides the dopant/polymer interaction, the solvent/polymer and solvent/dopant interactions are also considered to evaluate the kinetic effect on N-DMBI distribution by drawing the ternary phase diagram. We conclude that the kinetic morphological evolution doesn’t change the miscibility governed N-DMBI distribution in the BHJ film. Finally, we provide a direct relationship between the N-DMBI position and the device property by fabricating the bi-layer devices. The enhancement of photovoltaic performances is observed in both of material systems only if the N-DMBI distributes in N2200. Our work outlines a basis for using the dopant/component interaction and ternary phase diagram to predict the dopant distribution before extensive experiments. It significantly reduces the trial-to-error work and increases the reliability of molecularly doped PSCs.
关键词： n-doping,polymer solar cell,doped morphology,ternary phase diagram,Molecular doping
更新于2025-09-23 15:19:57
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High-Performance Ternary Organic Solar Cells with Controllable Morphology via Sequential Layer-by-Layer Deposition
摘要： Ternary blending of light harvesting materials has been proven to be a potential strategy to improve the efficiency of solution processed organic solar cells (OSCs). However, the optimization of ternary system is usually more complicated than the binary one as the morphology of conventional ternary blend films is very difficult to control, thus undermining the potential of ternary OSCs. Herein, we report a general strategy for better control of the morphology of ternary blend films composed of a polymer donor and two non-fullerene small molecule acceptors for high-performance OSCs using sequential layer-by-layer (LbL) deposition method. The resulted LbL films form bicontinuous interpenetrating network structure with high crystallinity of both the donor and acceptor materials, showing efficient charge generation, transport and collection properties. In addition, the power conversion efficiencies (PCEs) of the ternary LbL OSCs are less sensitive to the blending ratio of the third component acceptor, providing more room to optimize the device performance. As a result, optimal PCEs of over 11%, 13 % and 16 % were achieved for the LbL OSCs composed of PffBT4T-2OD/IEICO-4F:FBR, PBDB-T-SF/IT-4F:FBR and PM6/Y6:FBR, respectively. Our work provides useful and general guidelines for the development of more efficient ternary OSCs with better controlled morphology.
关键词： sequential layer-by-layer deposition,non-fullerene acceptor,ternary organic solar cell,high performance,morphology control
更新于2025-09-23 15:19:57
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Nanoscaled Fractal Superstructures via Laser Patterninga??A Versatile Route to Metallic Hierarchical Porous Materials
摘要： A laser-based procedure for the preparation of metallic hierarchical porous materials is introduced and exemplified on tin, copper, silicon, titanium, and tungsten surfaces to demonstrate its general applicability. The impact of suitably tuned nanosecond laser pulses triggers a process in which laser-induced metal ablation and instantaneous recondensation of partially oxidized metals lead to cauliflower-like superstructures comprising a hybrid micro-/nanopatterning. Repeated scanning with the intense focused beam over the surface creates microstructures of hierarchically tunable porosity in a layer-by-layer design. The 3D morphology of these superstructures is analyzed using tomographic data based on focused ion-beam scanning electron microscopy to return a fractal dimension of Df = 2.79—practically identical to a natural cauliflower (Df ≈ 2.8), even though the plant is four orders of magnitude larger than the superstructures generated through the laser process. The high Df value signifies a complex morphology that boasts a huge external surface. The introduced concept enables convenient access to a variety of metallic hierarchical porous materials, which are key to performance in environmentally and technologically relevant areas like energy generation, storage, and conversion, as well as sensing and catalysis.
关键词： fractal morphology,cauliflower-like superstructures,porous nanostructures,self-organizing microstructures,scalable patterning
更新于2025-09-23 15:19:57
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Experimentally Calibrated Kinetic Monte Carlo Model Reproduces Organic Solar Cell Currenta??Voltage Curve
摘要： Kinetic Monte Carlo simulations are used to describe the current-voltage characteristics of an organic bulk heterojunction solar cell. Excellent agreement between model and experiment is obtained by calibrating the injection barriers, the blend morphology and the charge transfer recombination rate with data from independent measurement techniques.
关键词： organic photovoltaics,charge recombination,Kinetic Monte Carlo simulations,morphology,charge injection
更新于2025-09-23 15:19:57
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A New Benzodithiophene Based Donor-Acceptor ??-Conjugated Polymer for Organic Solar Cells
摘要： A new benzodithiophene based donor-acceptor π-conjugated polymer (P1) is designed and explored as the photoactive donor for organic solar cells (OSCs). The synthesized donor polymer, P1 displays a wide absorption profile ranging from 300-750 nm with optical band gap of 1.61 eV and moderate ionization potential of -5.30 eV. It has good solubility in non-halogenated and halogenated organic solvents. Next, we fabricated OSCs with P1 by blending with PC71BM, the pristine polymer processed from chlorobenzene showed PCE of 2.79%. Upon addition of external additive diphenyl ether to the blend showed a dramatic improvement in PCE with maximum of 5.33%. DPE tailored the active layer morphology and showed two times higher PCE than pristine films. These results clearly indicate that the new polymer has a great potentiality for enhancing efficiency upon solvent additives, which will provide new routes for the development of new class of polymers for high-performance air-stable OSCs.
关键词： benzodithiophene based π-conjugated polymer,organic solar cell,morphology,octyl side chain
更新于2025-09-23 15:19:57
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Dual Function of Surface Alkali-Gas Erosion on SnO <sub/>2</sub> for Efficient and Stable Perovskite Solar Cells
摘要： The electrical character and interface contact of electron transport layer (ETL) play a critical role on high efficiency planar perovskite solar cells (PSCs). Here, a dual functional surface alkali-gas erosion (SAE) method is proposed based on the unique chemical properties of the amphoteric oxide. Firstly, during the SAE process, the SnO2 can react with alkaline gas slightly and the chemical reaction mechanism is elucidated, which leads to the crystal fusion of the SnO2 surface, bringing an improved electron mobility and an excellent interface contact between SnO2 ETL and perovskite layer. Secondly, SAE method introduced -NH2 group on SnO2 surface chemically can provide nuclear site of perovskite crystal and promote the growth of perovskite film, meanwhile, the -NH2 group connected chemically with SnO2 also serves as a bridge-link by replacing the organic cation at the perovskite/SnO2 interface, which effectively enhances the interfacial charge transport and the perovskite crystallinity. As a consequence, devices with SAE achieve a champion PCE of 21.10% and the average PCE is increased from 18.07% to 20.30%, which mainly results from the increase of short-circuit current density from 22.34 mA/cm2 to 24.19 mA/cm2. Moreover, the optimized devices retain 86% of its initial PCE (compared with 41% of control device) after 60 days at room temperature with 40%–50% humidity.
关键词： Interfacial bonding,Perovskite solar cells,Crystal nucleation,Surface alkali-gas erosion,Surface morphology modulation
更新于2025-09-23 15:19:57
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Mesoscopic study of thermal behavior, fluid dynamics and surface morphology during selective laser melting of Ti-based composites
摘要： A mesoscopic simulation based on the randomly packed powder bed model was developed to study the thermal behaviors during selective laser melting (SLM) of Ti-based composites. Effects of processing parameters on the thermal behavior, fluid dynamics and surface morphology evolution within the molten pool were investigated. The obtained results revealed that the operating temperature, cooling rate and melt lifetime were highly enhanced as the laser power was increased. Meanwhile, the increased molten pool dimensions, the turbulent fluid flows, the improved escaping rate of the entrapped gas and the efficient rearrangement of reinforcing particles within the molten pool appeared at the application of the high laser power. At the optimized processing parameters, the peak of the operating temperature profile located in the laser and powder interaction area was apparently disappeared with the formation of the maximum temperature of 3300 K and, the mean operating temperature of the platform caused by the heat accumulation was as high as 1300 K. Moreover, the surface morphology of the molten pool predicted by the simulation showed a variation from continuous pores to fragments, then to the typical and regular liquid front, and finally to the turbulent liquid front and spatter and balling phenomenon as the laser power increased. At the laser power of 200 W and laser energy density of 140 J/m, the maximum velocity was located in the front and rear region and, the velocity vector located in the melt advanced front pointed to the rear region of the molten pool, indicating that the melt from the irradiation region would complete the efficient melt supplement and avoid the formation of residual pores and therefore, a good and flat surface with few spatters was obtained with the clear liquid front. The simulated surface morphology was found to be consistent with the experimental measurements.
关键词： Surface morphology,Thermodynamics,Mesoscopic simulation,Selective laser melting,Titanium matrix composite
更新于2025-09-23 15:19:57