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Naphthalene Diimide-Based Terpolymers with Controlled Crystalline Properties for Producing High Electron Mobility and Optimal Blend Morphology in All-Polymer Solar Cells
摘要： We report a series of new n-type random copolymers (P(NDI2OD-Se-Th x) where x = 0, 0.5, 0.7, 0.8, 0.9, 1.0) consisting of naphthalene diimide (NDI), selenophene-2,2’-thiophene (Se-Th), and seleno[3,2-b]thiophene (SeTh) to demonstrate their use in producing efficient all-polymer solar cells (all-PSCs) and organic field-effect transistors (OFETs). To investigate the effect of polymer crystallinity on the performance of all-PSCs and OFETs, we tuned the composition of the Se-Th and SeTh moieties in the P(NDI2OD-Se-Th x) polymers, resulting in enhanced crystalline properties with higher Se-Th ratio. Thus, the OFET electron mobility was increased with higher Se-Th ratio, exhibiting the highest value of 1.38×10?1 cm2 V?1 s?1 with P(NDI2OD-Se-Th 1.0). However, the performance of all-PSCs based on PBDB-T:P(NDI2OD-Se-Th x) showed a non-linear trend relative to the Se-Th ratio and the performance was optimized with P(NDI2OD-Se-Th 0.8) exhibiting the highest power coversion efficiency of 8.30%. This is attributed to the stronger crystallization-driven phase separation in all-polymer blends for higher Se-Th ratio. At the optimal crystallinity of P(NDI2OD-Se-Th 0.8) in all-PSCs, the degree of phase separation, domain purity and the electron mobility were optimized, resulting in enhanced charge generation and transport. Our works describe structure-property-performance relationships to design effective n-type polymers in terms of crystalline and electrical properties suitable for both efficient OFETs and all-PSCs.
关键词： organic field-effect transistors,seleno[3,2-b]thiophene,polymer crystallinity,n-type random copolymers,selenophene-2,2’-thiophene,charge generation,all-polymer solar cells,charge transport,naphthalene diimide
更新于2025-09-19 17:13:59
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π–π Stacking Distance and Phase Separation Controlled Efficiency in Stable All-Polymer Solar Cells
摘要： The morphology of the active layer plays a crucial role in determining device performance and stability for organic solar cells. All-polymer solar cells (All-PSCs), showing robust and stable morphologies, have been proven to give better thermal stability than their fullerene counterparts. However, outstanding thermal stability is not always the case for polymer blends, and the limiting factors responsible for the poor thermal stability in some All-PSCs, and how to obtain higher efficiency without losing stability, still remain unclear. By studying the morphology of poly [2,3-bis (3-octyloxyphenyl) quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl](TQ1)/poly[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl]] (PCE10)/PNDI-T10 blend systems, we found that the rearranged molecular packing structure and phase separation were mainly responsible for the poor thermal stability in devices containing PCE10. The TQ1/PNDI-T10 devices exhibited an improved PCE with a decreased π–π stacking distance after thermal annealing; PCE10/PNDI-T10 devices showed a better pristine PCE, however, thermal annealing induced the increased π–π stacking distance and thus inferior hole conductivity, leading to a decreased PCE. Thus, a maximum PCE could be achieved in a TQ1/PCE10/PNDI-T10 (1/1/1) ternary system after thermal annealing resulting from their favorable molecular interaction and the trade-off of molecular packing structure variations between TQ1 and PCE10. This indicates that a route to efficient and thermal stable All-PSCs can be achieved in a ternary blend by using material with excellent pristine efficiency, combined with another material showing improved efficiency under thermal annealing.
关键词： morphology,device stability,crystallinity,all-polymer solar cells,thermal annealing,molecular packing structure
更新于2025-09-19 17:13:59
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Two-Dimensional Bi <sub/>2</sub> O <sub/>2</sub> Se with High Mobility for High-Performance Polymer Solar Cells
摘要： Carrier mobility is a critical factor for power conversion efficiency (PCE) of polymer solar cells (PSCs), and the low charge carrier mobility still limits performance improvement of PSCs. Adding high mobility material into the active layer is one of the better ways to enhance the PCE of PSCs. Two-dimensional (2D) Bi2O2Se can be an ideal additive material for improving the carrier mobility of PSCs because its ultrahigh mobility and high thermal stability. In this work, the Bi2O2Se few-layer 2D nanoflakes are fabricated by combining lithium intercalation with shear force-assisted liquid phase exfoliation and applied as an additive to promote charge transport in PSCs for the first time. The 2D Bi2O2Se nanoflakes, when introduced into the active layer, not only provide new interface between donor and acceptor and efficient charge transfer pathways but also induce crystallization of photosensitive layer and form the continuous interpenetrating networks, which promotes the exciton separation and charge transfer in photosensitive layer. As a result, the PCE of device based on PBDB-T:ITIC is increased from 10.09% (0 wt%) to 12.22% (2 wt%). Meanwhile, the PCE of device based on PM6:Y6 is also increased from 14.59% for binary device to 16.28% for optimized ternary device (2 wt%). Moreover, the optimized ternary device shows excellent air stability by suppressing the mixing of the two phases. This work supplies a good method to enhance the PCE of PSCs, also shows the Bi2O2Se material has a good prospect in photovoltaic devices.
关键词： crystallinity,charge recombination,Polymer solar cells,stability,carrier mobility,2D Bi2O2Se flakes
更新于2025-09-19 17:13:59
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Thermally Stable Aua??BaTiO <sub/>3</sub> Nanoscale Hybrid Metamaterial for High-Temperature Plasmonic Applications
摘要： The thermal stability of the Au?BaTiO3 nanocomposite thin film as a hybrid metamaterial deposited by a one-step pulsed laser deposition (PLD) method has been investigated via both ex situ annealing followed by TEM analysis and an in situ heating study in TEM. For the ex situ annealing study, the XRD analysis shows good crystallinity for both as-deposited and annealed films after being annealed at 600 °C for different time periods (i.e. 1, 3, 6, and 30 hours). The optical measurements including transmittance/reflectance, ellipsometry, and Raman spectroscopy demonstrate excellent optical properties of the hybrid metamaterial films by exhibiting the static localized surface plasmon resonance (LSPR) peak and hyperbolic dispersion in the visible to near-infrared regime. Both TEM results of the ex situ annealed samples and in situ heating TEM results reveal no obvious microstructure change after the extensive high-temperature annealing and suggest the high thermal stability of the Au?oxide hybrid materials for their future high-temperature plasmonic applications.
关键词： crystallinity,localized surface plasmon resonance,in situ,hyperbolic dispersion,hybrid metamaterial,thermal stability,ex situ
更新于2025-09-19 17:13:59
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All-Small-Molecule Organic Solar Cells with an Ordered Liquid Crystalline Donor
摘要： A new small-molecule donor, namely BTR-Cl, which possesses a strong liquid crystalline property and high crystallinity, works well with the non-liquid crystalline acceptor Y6 and gives a record-high power conversion efficiency (PCE) of 13.6% in single-junction all-small-molecule organic solar cells. The BTR-Cl:Y6-based device was certified at the National Institute of Metrology, certifying a PCE of 13.0%.
关键词： All-small-molecule organic solar cells,Phase separation,Liquid crystalline donor,Power conversion efficiency,High crystallinity
更新于2025-09-19 17:13:59
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Tailoring morphology compatibility and device stability by adding PBDTTPD-COOH as third component to fullerene-based polymer solar cells
摘要： The crystallinity and morphology of polymer and fullerene have a profound influence on the performance of bulk heterojunction (BHJ) organic photovoltaic devices. The poor compatibility of donor and acceptor molecules in the BHJs hinders the further improvement of the device performance and stability in organic solar cells. In this work, the conjugated polymer PBDTTPD-COOH is introduced as a third component into BHJ films of PTB7-Th:PC71BM and PffBT4T-2OD:PC71BM to improve the crystallinity and morphology. The crystallinity of both donor polymers is enhanced and more face-on orientated crystals are observed in the corresponding films, which is correlated with the improvement of the current density of the related solar cells. Also, the improved BHJ morphology leads to an increased fill factor. Furthermore, the device stability significantly increases by the addition of the third component PBDTTPD-COOH. The T80 lifetime value is enhanced 10 times in the doped devices as compared with the binary solar cells in the case of the PTB7-Th:PC71BM series.
关键词： stability,crystallinity,organic photovoltaic,additive,face-on orientation
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Determination of Crystallinity, Composition, and Thermal stability of Ethylene Vinyl Acetate Encapsulant used for PV Module Lamination
摘要： Ethylene Vinyl Acetate (EVA) Copolymer is a most commonly used encapsulant for PV module lamination. Using cured and uncured EVA, several key characteristics of EVA have been determined. The glass transition temperature, peak melting point, degree of crystallinity has been determined with the help of Differential scanning calorimeter (DSC) analysis. Thermogravimetric analysis (TGA) is done to determine the Vinyl Acetate content and the thermal stability based on degradation onset temperature. This work will help to understand the thermal behavior and initial VA content estimation of the unknown grade of EVA encapsulant, which greatly affects the final module reliability.
关键词： encapsulant,crystallinity,thermal stability,ethylene vinyl acetate,photovoltaics
更新于2025-09-19 17:13:59
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Hydrothermal growth of n-ZnO films on a patterned p-GaN epilayer and its application in heterojunction light-emitting diodes
摘要： The hydrothermal growth (HTG) of crystalline n-ZnO ?lms on both the nonpatterned and patterned p-GaN epilayers with a honeycomb array of etched holes is demonstrated, and its application in n-ZnO/p-GaN heterojunction light-emitting diodes (HJ-LEDs) is reported. The results reveal that an HTG n-ZnO ?lm on a patterned p-GaN layer exhibits a high-quality single crystal with FWHMs of 0.463 and 0.983° obtained from a ω-rocking curve and a ?-scan pattern, respectively, which are much better than those obtained on a nonpatterned p-GaN layer. In addition, the n-ZnO/patterned p-GaN HJ-LED exhibited a much better rectifying diode behavior owing to having a higher n-ZnO ?lm crystallinity quality and an improved interface with the p-GaN layer. Strong violet and violet-blue lights emitted from the n-ZnO/patterned p-GaN HJ-LED at around 405, 412, and 430 nm were analyzed.
关键词： crystallinity quality,n-ZnO films,heterojunction light-emitting diodes,hydrothermal growth,p-GaN epilayer
更新于2025-09-19 17:13:59
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Effect of polymer donor aggregation on active layer morphology of amorphous polymer acceptor-based all-polymer solar cells
摘要： Most of polymer acceptors for all-polymer solar cells (all-PSCs) are semi-crystalline. Amorphous polymer acceptors containing B←N unit represent a new kind of acceptor materials and possess unique phase separation behaviours in all-PSCs. In this work, to study their phase separation morphology and all-PSC device performance, we select three polymer donors with identical polymer backbone but different side chains to blend with an amorphous polymer acceptor (rr-PBN). Among the three polymer donors, J91 exhibits the strongest aggregation tendency in solution and moderate crystallinity in thin film. The J91:rr-PBN blend shows the most optimal phase separation morphology and the best all-PSC device performance. In comparison, J51 shows the least aggregation tendency in solution and the highest crystallinity in thin film. The all-PSC device of J51:rr-PBN blend exhibits sub-optimal active layer morphology and poor photovoltaic performance. These results indicate that the aggregation tendency in solution of polymer donor is the dominant factor in the phase separation of semi-crystalline polymer donor/amorphous polymer acceptor blend in all-PSCs.
关键词： crystallinity,morphology,all-polymer solar cells,aggregation in solution,phase separation
更新于2025-09-19 17:13:59
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Unraveling the Structure-Property Relationship of Molecular Hole Transporting Materials for Perovskite Solar Cells
摘要： Clarifying the structural basis and microscopic mechanism lying behind electronic properties of molecular semiconductors is of paramount importance in further materials design to enhance the performance of perovskite solar cells. In this paper, three conjugated quasi-linear segments of 9,9-dimethyl-9H-fluorene, 9,9-dimethyl-2,7-diphenyl-9H-fluorene, and 2,6-diphenyldithieno[3,2-b:2',3'-d]thiophene are end-capped with two bis(4-methoxyphenyl)amino groups for structurally simple molecular semiconductors Z1, Z2, and Z3, which crystalline in the monoclinic, triclinic, and monoclinic space groups, respectively. The modes and energies of intermolecular noncovalent interactions in various closely packed dimers extracted from single crystals are computed based on the quantum theory of atoms in molecules and energy decomposition analysis. Transfer integrals, reorganization energies, and center-of-mass distances in these dimers as well as band structures of single crystals are also calculated to define the theoretical limit of hole transport and microscopic transport pictures. Joint X-ray diffraction and space-charge limiting current measurements on solution-deposited films suggest the dominant role of crystallinity in thin film hole mobility. Photoelectron spectroscopy and photoluminescence measurements show that an enhanced interfacial interaction between perovskite and Z3 could attenuate the adverse impact of reducing the energetic driving force of hole extraction. Our comparative studies show that molecular semiconductor Z3 with a properly aligned HOMO energy level and a high thin film mobility can be employed for efficient perovskite solar cells, achieving a good power conversion efficiency of 20.84%, which is even higher than that of 20.42% for spiro-OMeTAD control.
关键词： charge recombination,perovskite solar cell,molecular crystal,noncovalent interaction,crystallinity,charge transport,organic semiconductor
更新于2025-09-16 10:30:52