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Exploring a fused 2-(thiophen-2-yl)thieno[3,2-b]thiophene (T-TT) building block to construct n-type polymer toward high performance all-polymer solar cells
摘要： In the field of all-polymer solar cells (all-PSCs), exploring new electron-donating units (D) to match with electron-accepting units (A) is an important subject to promote the performance of D-A type polymer acceptors. Herein, we developed a fused D unit 2-(thiophen-2-yl)thieno[3,2-b]thiophene (T-TT) derivated from the famous 2-(2-(thiophen-2-yl)vinyl)thiophene (TVT) unit. With classical naphthalene diimide (NDI) as A unit, the new D-A polymer PNDI-T-TT exhibits enhanced absorption coefficient, electron mobility and miscibility with donor polymer in comparison with the analogous PNDI-TVT polymer. These advantages can be attributed to the enlarged conjugation and reduced rotamers due to the fused T-TT unit, leading to stronger intermolecular interaction. When blending with the donor polymer PBDB-T, both NDI-based polymers can form better interpenetrating nanostructures than the corresponding blend films with donor polymer J71. Finally, PBDB-T:PNDI-T-TT device obtains a power conversion efficiency (PCE) of 6.1%, which is much higher than that of PBDB-T:PNDI-TVT device (4.24%). These results demonstrate that n-type polymer based on fused T-TT unit can ameliorate the absorption coefficient, molecular aggregation and charge carrier mobility and consequently achieve improved photovoltaic performance in comparison with classic TVT unit.
关键词： All-polymer solar cells,2-(2-(thiophen-2-yl)vinyl)thiophene,PBDB-T,naphthalene diimide,photovoltaic
更新于2025-09-19 17:13:59
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Achieving Optimal Bulk Heterojunction in All-Polymer Solar Cells by Sequential Processing with Nonorthogonal Solvents
摘要： Developing efficient all-polymer solar cells (all-PSCs) has always been a long-standing challenge due to the unfavorable morphology caused by conventional blend-casting (BC). Here we first employ the methodology of sequential processing (SP) with nonorthogonal solvents to fabricate facilely all-PSCs. A highly crystalline polymer donor PBDB-T is used to construct a well-organized underlying film, while a new polymer FPDI-BT1 is selected as the acceptor to be intercalated into the amorphous or semicrystalline regions of PBDB-T during the secondary deposition. By tuning the solvent composition for FPDI-BT1 processing, a bulk heterojunction-like configuration, rather than a traditional bilayer device, is obtained facilely without the need of further processing treatment. The extremely boosted power conversion efficiency of 7.15% from SP device is achieved, which is more than twice as efficient as the BC analogue (3.57%). The results demonstrate that SP is a promising strategy to fabricate high-performance all-PSCs with tunable configurations of active layers.
关键词： perylene diimide,non-fullerene acceptor,sequential processing,all-polymer solar cells,morphological control
更新于2025-09-19 17:13:59
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Modifying the nanostructures of PEDOT:PSS/Ti3C2TX composite hole transport layers for highly efficient polymer solar cells
摘要： Two-dimensional (2D) transition metal carbides MXene, typically represented by Ti3C2TX, have shown great promise in optoelectronic devices due to their metallic electrical conductivity, large surface area, superior hydrophilicity and excellent transparency. Herein, to improve the conductivity of polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film, we incorporate solution-processable 2D Ti3C2Tx nanosheets into PEDOT:PSS to fabricate PEDOT:PSS/Ti3C2TX composite layers, and polymer solar cells (PSCs) with PEDOT:PSS/Ti3C2TX composite films as hole transport layers (HTLs) are fabricated for the first time. The nanostructures and the corresponding hole injection properties of PEDOT:PSS/Ti3C2TX composite layers are systematically evaluated. Based on the non-fullerene PBDB-T:ITIC system, a power conversion efficiency (PCE) of 11.02% is obtained for the device with PEDOT:PSS/Ti3C2TX as HTL, which is improved by 13.5% than that of the control device with pure PEDOT:PSS as HTL (9.72%). When using the PM6:Y6 system as the active layer, the PCE of the device based on PEDOT:PSS/Ti3C2TX is improved to 14.55% from 13.10% for the PEDOT:PSS reference device. 2D Ti3C2TX nanoflakes with higher conductivity constructing additional charge transfer pathways between the PEDOT nanocrystals and inducing conformational transition of PEDOT from a coil to a liner/expanded-coil structure, leading to the conductivity and device performance improvement. Interestingly, PEDOT:PSS/Ti3C2TX based devices also exhibit enhanced long-term stability than PEDOT:PSS based device. These results show that PEDOT:PSS/Ti3C2TX composite film has a promising prospect in high efficiency organic optoelectronics.
关键词： PEDOT:PSS/Ti3C2Tx composite film,hole injection property,improved conductivity,polymer solar cells,hole transport layer
更新于2025-09-19 17:13:59
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High-Performance Ambient-Condition-Processed Polymer Solar Cells and Organic Thin-Film Transistors
摘要： Large-scale commercial synthesis of bulk-heterojunction (BHJ) solar cell materials is very challenging and both time and energy consuming. Synthesis of π-conjugated polymers (CPs) with uniform batch-to-batch molecular weight and low dispersity is a key requirement for better reproducibility of high-efficiency polymer solar cells. Herein, a conjugated polymer (CP) PTB7-Th, well known for its high performance, has been synthesized with high molecular weight and low dispersity in a closed microwave reactor. The microwave reaction procedure is known to be more controlled and consumes less energy. The precursors were strategically reacted for different reaction time durations to obtain the optimum molecular weight. All different CPs were well characterized using 1H NMR, gel permeation chromatography (GPC), UV?vis, photoluminescence (PL), electron spin resonance (ESR), and Raman spectroscopy, whereas the film morphology was extensively studied via atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXRD) techniques. The effect of molecular weight on a conventional BHJ solar cell with PC71BM acceptor was investigated to derive systematic structure?property relationships. The CP obtained after 35 min of reaction time and integrated into BHJ devices under ambient conditions provided the best performance with a power conversion efficiency (PCE) of 8.09%, which was quite similar to the results of CPs synthesized via a thermal route. An enhanced PCE of 8.47% was obtained for the optimized polymer (35 min microwave reaction product) when device fabrication was carried out inside a glovebox. The organic thin-film transistor (OTFT) device with the microwave-synthesized CP displayed better hole mobility (0.137 cm2 V?1 s?1) as compared to that with the thermally synthesized CP. This study also proved that the device stability and reproducibility of the microwave-synthesized CP were much better and more consistent than those of the thermally developed CP.
关键词： microwave reactor,π-conjugated polymers,organic thin-film transistors,polymer solar cells,bulk-heterojunction
更新于2025-09-19 17:13:59
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EFFECTIVENESS OF ANNEALING TREATMENT AND POLYMER BLENDS ON I-V CHARACTERISTSICS OF POLYMER SOLAR CELL
摘要： This research reports on a fabrication of polymer solar cells based on blends of two widely used polymeric semiconductors i.e. poly(2-methoxy-5-(3,7-dimethyloctyloxy)-para phenylene vinylene) (MDMO-PPV) and the soluble fullerene C60 derivative [6,6 phenyl C61-butyric acid methyl ester] (PCBM). The devices were fabricated on an indium tin oxide (ITO) coated glass substrate. After cleaned and dried, a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in H2O was spin coated onto the freshly prepared substrate and then dried in a vacuum oven at 120°C for 60 minutes. A blend of MDMO-PPV and PCBM in chlorobenzene was spin coated on the top and dried in a nitrogen ambient at room temperature for 24 hours. The devices were transferred to a sputtering system where an aluminum was coated. Some of the devices then were annealed in a vacuum oven at 60°C for 60 minutes. Finally, the devices were encapsulated by placing a sealant between the back of the devices and glass slides and then cured in a vacuum oven at temperature 100°C for 10 minutes. For characterization, the devices were illuminated with a xenon lamp at the intensity of 27 mW/cm2 and the temperature at approximately 25°C. The influence of the annealing treatment and polymer blends on the photovoltaic performance of the devices was also discussed here. The best performance was obtained from the device with a blend ratio of 1:1 MDMO-PPV/PCBM without annealing treatment. The typical power efficiency was 0.01% with open circuit voltage of 0.347 V, short circuit current of 0.064 mA, and maximum power of 0.006 mW.
关键词： polymer solar cells,annealing,polymeric semiconductor
更新于2025-09-19 17:13:59
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A nona??fullerene acceptor with chlorinated thienyl conjugated side chains for higha??performance polymer solar cells via toluene processing
摘要： Small molecular acceptors (SMAs) BTC-2F and BTH-2F, based on heptacyclic benzodi(cyclopentadithiophene) electron-donating core (CBT) with chlorinated-thienyl conjugated and thienyl conjugated side chains, respectively, are designed and synthesized. Relative to non-chlorine acceptor BTH-2F, BTC-2F exhibits slightly blue-shifted absorption spectra, similar the lowest unoccupied molecular orbital (LUMO) (-3.91 eV), deeper highest occupied molecular orbital (HOMO) energy level and higher electron mobility than that of BTH-2F. PM6, a wide bandgap polymer, is selected as the donor material to construct bulk heterojunction polymer solar cells processed with nonhalogenated solvent toluene. The optimized PM6:BTC-2F-based device presents a 12.9% power conversion efficiency (PCE), while the PCE of PM6:BTH-2F-based device is only 11.3%. The results suggest that it is an effective strategy to optimize the photoelectric properties of SMAs by incorporating chlorine atom into the conjugated side chains.
关键词： small molecular acceptors,narrow bandgap,power conversion efficiency,chlorinated-thienyl,polymer solar cells
更新于2025-09-19 17:13:59
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Twoa??Dimension Conjugated Acceptors Based on Benzodi(cyclopentadithiophene) Core with Thiophenea??Fused Ending Group for Efficient Polymer Solar Cells
摘要： The previously reported nonfullerene small molecule ITIC-SF achieved via side chain tuning, promotes the power conversion efficiency of polymer solar cells (PSCs) with PBDB-T-SF as the donor from 10.1% and ITIC2 acceptors up to 12.2% for ITIC-SF acceptors. To further this research, benzene end groups of molecules are herein substituted with thiophene rings, obtaining two new molecules BDTCH-IC with alkylthio substituents, and BDTSF-IC with alkylthio and fluorine substituents on their thiophene-conjugated side chains. The absorption edges of BDTCH-IC and BDTSF-IC are red-shifted to 824 and 793 nm, respectively. Strengthened molecular crystallinity, promoted charge extraction, and upgraded morphology endorse the advancement of photovoltaic performance of the small molecular acceptors. Using donor PM6, the two small molecule acceptors show good photovoltaic performance, although the highest occupied molecular orbit energy offsets are small between donor and acceptor materials. As a combination of side-chain and end-group engineering, the photovoltaic performance of the PSCs is increased to 13.1%, together with the best short-circuit current (JSC) and fill factor reported thus far for this series of molecules. The results indicate that the modification of side chain and end groups is an effective way to improve the photovoltaic performance of small molecule acceptors.
关键词： small molecules acceptors,nonfullerenes,end groups,side-chain engineering,polymer solar cells
更新于2025-09-19 17:13:59
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Asymmetric Siloxane-Functional Side Chains Enable High-Performance Donor Copolymers for Photovoltaic Applications
摘要： In this work, three benzodithiophene (BDT)-benzotriazole (BTA) alternated wide bandgap (WBG) copolymers attaching symmetric or asymmetric conjugated side chains, namely PDBTFBTA-2T, PBDTFTBA-TSi and PBDTFBTA-2Si, were developed for efficient nonfullerene polymer solar cells. The symmetry effect of the side chains was investigated in detail on the overall properties of these donor polymers. The results demonstrated that the introduced siloxane functional groups showed less effect on the absorptions and frontier orbital levels of the prepared polymers but had significant effect on the miscibility between these polymer donors and nonfullerene acceptor. If increasing the content of siloxane functional groups, the miscibility of the polymer donors and Y6 would be improved, leading to the decreased domain size and more mixed domains. Interestingly, the active blend based on PBDTFTBA-TSi with asymmetric side chains exhibited more balanced miscibility, carrier mobility and phase separation, benefiting exciton diffusion and dissociation. Therefore, a champion power conversion efficiency (PCE) of 14.18% was achieved finally in PBDTFTBA-TSi devices, which was 20.6% and 19.0% higher than the symmetric counterparts of PBTFBTA-2T devices (PCE = 11.76%) and PBDTFBTA-2Si devices (PCE = 11.92%), respectively. This work highlights that the asymmetric side chain engineering based on siloxane functional groups is a promising design strategy for high-performance polymer donor semiconductors.
关键词： molecular design strategy,nonfullerene polymer solar cells,siloxane functional group,wide bandgap copolymers,asymmetric side chains
更新于2025-09-19 17:13:59
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Insight into the Efficiency and Stability of All-Polymer Solar Cells Based on Two 2D-Conjugated Polymer Donors: Achieving High Fill Factor of 78%
摘要： Achieving high fill factor (FF) is a great challenge for the all polymer solar cells (all-PSCs) since the FF can be influenced by numerous complicated factors. In this work, two medium bandgap 2D-conjugated copolymers J61 and J71 with varied side chains were utilized as donor to construct efficient all-PSCs with the typical electron-withdrawing polymer N2200 as acceptor. Eventually, moderate photovoltaic performance was obtained for J61:N2200 device with power conversion efficiency (PCE) of 6.58% and FF of 60.18%. While the J71:N2200-based all-PSCs delivered an outstanding PCE of 9.31% with an unprecedented FF of 78.00%. To the best of our knowledge, such an FF of 78% represents a record value for binary all-PSCs systems, which demonstrates that the all-PSCs can realize excellent FF comparable to other PSCs systems. The favorable blends morphology, molecular orientation, balanced charge transport and suppressed recombination together contributed to the remarkable photovoltaic performance of J71:N2200 devices. In addition, relatively weak thickness-dependence of photovoltaic property and excellent long-term device stabilities (in N2 and air, respectively) were observed for the J71:N2200 all-PSCs. These results reveal that J71 with trialkylsilyl side chains is a promising polymer donor candidate for developing high performance all-PSCs for future practical application.
关键词： high efficiency,fill factor,stability,all-polymer solar cells,donor
更新于2025-09-19 17:13:59
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Influences of the terminal groups on the performances of asymmetric small molecule acceptors-based polymer solar cells
摘要： By altering the end-capping groups from 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile to 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile and 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile, three asymmetric non-fullerene electron-acceptors (T-TT, T-TT-4F, and T-TT-4Cl) containing thiophene–phenylene–thieno[3,2-b]thiophene fused-ring as the electron-donating core were synthesized. Although the three asymmetric molecules all have bent geometries, the di-fluorinated and di-chlorinated acceptors show bathochromically-shifted spectra, enhanced molar extinct coefficients, deepened molecular energy levels, and reduced dipole moments. When blending with a wide-bandgap polymer PM6 in inverted solar cells, the T-TT-based device exhibits the highest open-circuit voltage (VOC) of 0.966 V, while the T-TT-4Cl-based device has the biggest short-circuit current density (JSC) of 19.00 mA cm?2, and the T-TT-4F-based device possesses the best fill factor (FF) of 66.1%, a moderate VOC (0.859 V), and a medium JSC (18.48 mA cm?2). As a result of the above properties and parameters, the T-TT-4F- and T-TT-4Cl-based solar cells successfully achieved high power conversion efficiencies of 10.49% and 10.16%, in comparison with that of 9.70% for the T-TT-based device, illustrating the importance of the influences of the terminal groups on the performances of asymmetric small molecular acceptors-based polymer solar cells.
关键词： Polymer solar cells,Dipole moment,Asymmetric non-fullerene small molecules,End-capping group modifications
更新于2025-09-19 17:13:59