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Design and Synthesis of Non-Fullerene Acceptors Based on Quinoxalineimide Moiety as the Central Building Block for Organic Solar Cells
摘要： Two new non-fullerene acceptors, namely QIP-4F and QIP-4Cl, contain a novel imide-functionalized quinoxaline (QI) moiety fused with thienylthiophene unit as the central building block, and chlorinated or fluorinated 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile as end-capping groups, were designed and synthesized, respectively. An optimized device based on P2F-EHp:QIP-4Cl presented a power conversion efficiency of 13.3%, with an impressively high open-circuit voltage of 0.94 V. The results demonstrate the great potential of QI-containing fused units as central building blocks for high-performance acceptors.
关键词： quinoxalineimide,organic solar cells,power conversion efficiency,non-fullerene acceptors
更新于2025-09-23 15:19:57
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Liquid phase exfoliation of MoS2 and WS2 in aqueous ammonia and their application in highly efficient organic solar cells
摘要： Simple, scalable and cost-effective synthesis of quality two-dimensional (2D) transition metal dichalcogenides (TMDs) is critical for fundamental investigations but also for the widespread adoption of these low-dimensional materials to an expanding range of device applications. Here, we report on the liquid-phase exfoliation (LPE) of molybdenum disulfide (MoS2) and tungsten disulfide (WS2) in aqueous ammonia (NH3 (aq)) as a greener alternative to commonly used but less environmentally friendly solvents. The synthesized nanosheets can be prepared in high concentrations (0.5-1 mg mL-1) and exhibit excellent stoichiometric and structural quality with a semiconducting character. These characteristics makes them ideal for application in organic optoelectronics, where optical transparency and suitable energetics are two important prerequisites. When MoS2 and WS2 are used as the sole hole transport layer materials in organic photovoltaics, cells with power conversion efficiency of 14.9 and 15.6%, respectively, are obtained highlighting the potential of the aqueous ammonia-based LPE method for the preparation of high quality TMDs. The method could potentially be extended to other TMDs.
关键词： aqueous ammonia,MoS2,liquid-phase exfoliation,organic solar cells,WS2
更新于2025-09-23 15:19:57
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Higha??Performance Pseudoplanar Heterojunction Ternary Organic Solar Cells with Nonfullerene Alloyed Acceptor
摘要： The vast majority of ternary organic solar cells are obtained by simply fabricating bulk heterojunction (BHJ) active layers. Due to the inappropriate distribution of donors and acceptors in the vertical direction, a new method by fabricating pseudoplanar heterojunction (PPHJ) ternary organic solar cells is proposed to better modulate the morphology of active layer. The pseudoplanar heterojunction ternary organic solar cells (P-ternary) are fabricated by a sequential solution treatment technique, in which the donor and acceptor mixture blends are sequentially spin-coated. As a consequence, a higher power conversion efficiency (PCE) of 14.2% is achieved with a Voc of 0.79 V, Jsc of 25.6 mA cm?2, and fill factor (FF) of 69.8% compared with the ternary BHJ system of 13.8%. At the same time, the alloyed acceptor is likely formed between two the acceptors through a series of in-depth explorations. This work suggests that nonfullerene alloyed acceptor may have great potential to realize effective P-ternary organic solar cells.
关键词： ternary organic solar cells,sequential spin-coating,pseudoplanar heterojunctions,nonfullerene alloyed acceptors
更新于2025-09-23 15:19:57
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Boosting Performance of Nona??Fullerene Organic Solar Cells by 2D ga??C <sub/>3</sub> N <sub/>4</sub> Doped PEDOT:PSS
摘要： The power-conversion efficiency (PCE) of single-junction organic solar cells (OSCs) has exceeded 16% thanks to the development of non-fullerene acceptor materials and morphological optimization of active layer. In addition, interfacial engineering always plays a crucial role in further improving the performance of OSCs based on a well-established active-layer system. Doping of graphitic carbon nitride (g-C3N4) into poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as a hole transport layer (HTL) for PM6:Y6-based OSCs is reported, boosting the PCE to almost 16.4%. After being added into the PEDOT:PSS, the g-C3N4 as a Bronsted base can be protonated, weakening the shield effect of insulating PSS on conductive PEDOT, which enables exposures of more PEDOT chains on the surface of PEDOT:PSS core-shell structure, and thus increasing the conductivity. Therefore, at the interface between g-C3N4 doped HTL and PM6:Y6 layer, the charge transport is improved and the charge recombination is suppressed, leading to the increases of fill factor and short-circuit current density of devices. This work demonstrates that doping g-C3N4 into PEDOT:PSS is an efficient strategy to increase the conductivity of HTL, resulting in higher OSC performance.
关键词： hole-transport layers,PEDOT:PSS,organic solar cells,g-C3N4,non-fullerene acceptors
更新于2025-09-23 15:19:57
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The Role of Delocalization and Excess Energy in the Quantum Efficiency of Organic Solar Cells and the Validity of Optical Reciprocity Relations
摘要： The photon energy dependence of long-range charge separation is studied for two prototypical polymer:fullerene systems. The internal quantum efficiency (IQE) of PCDTBT:PC61BM is experimentally shown to be independent on the excitation energy. In contrast, for TQ1:PC71BM the IQE is strongly energy-dependent for excitation energies close to CT electroluminescence peak maximum while it becomes energy-independent at higher excitation energies. Kinetic Monte Carlo simulations reproduce the experimental IQE and reveal that the photon energy-dependence of the IQE is governed by charge delocalization. Efficient long-range separation at excitation energies corresponding to the CT electroluminescence peak maximum or lower requires an initial separation of the hole-electron pair by ～4-5nm, whereas delocalization is less important for charge separation at higher photon energies. Our modeling results suggest that a phenomenological reciprocity between CT electroluminescence and external quantum efficiency does not necessarily prove that commonly employed reciprocity relations between these spectra are valid from a fundamental perspective.
关键词： delocalization,optical reciprocity relations,quantum efficiency,organic solar cells,charge separation
更新于2025-09-23 15:19:57
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Enhanced Photovoltaic Performance by Synergistic Effect of Chlorination and Selenophene ??-Bridge
摘要： In the rapid innovation of organic solar cells, polymer donor plays a significant role in achieving high power conversion efficiencies (PCEs). The strong intermolecular interactions and deep highest occupied molecular orbitals (HOMOs) of donor polymers will facilitate the favorable phase separation and high open-circuit voltage (Voc), resulting in the dramatic improvement of device performance. Herein, combined chlorination of 4,8-bis(thiophene-2-yl)-benzo[1,2-b:4,5-b′]-dithiophene (T-BDT) and selenophene π-bridges, a new polymer donor, named PBBSe-Cl, is designed and synthesized. Compared to its parent polymer without chlorine substitution and π-bridge (named PBB), PBBSe-Cl exhibits much stronger absorption, better molecular planarity, and improved molecular aggregations. Moreover, PBBSe-Cl shows favorable phase separation and bicontinuous interpenetrating network when blending with acceptor Y6. As a result, the inverted device based on PBBSe-Cl achieves a decent PCE of 14.44%, with synchronously improved short-circuit current density (Jsc) of 24.07 mA cm?2 and fill factor (FF) of 73.16%. However, its parent polymers PBB and PBBSe-H only present a relatively low device performance. In addition, a very low energy loss (Eloss) of 0.51 eV is realized for PBBSe-Cl-based devices. This investigation proves that introducing chlorine atoms on the conjugated side chains and selenophene π-bridges will stepwise increase the polymer solar cell efficiency due to the simultaneous enhancement of device current density and fill factor. The proper usage of chlorination and selenophene π-bridge is a facile and efficient strategy for high-performance solar conversion materials.
关键词： selenophene π-bridges,organic solar cells,power conversion efficiencies,chlorination,polymer donor
更新于2025-09-23 15:19:57
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Hole-Transporting Poly(dendrimer)s as Electron Donors for Low Donor Organic Solar Cells with Efficient Charge Transport
摘要： Recent work on bulk-heterojunction organic solar cells has shown that photoexcitation of the electron acceptor followed by photoinduced hole transfer can play a significant role in photocurrent generation. To establish a clear understanding of the role of the donor in the photoinduced hole transfer process, we have synthesized a series of triphenylamine-based hole-transporting poly(dendrimer)s with mechanically flexible nonconjugated backbones via ring-opening metathesis polymerization and used them in low donor content solar cells. The poly(dendrimer)s were found to retain the hole transporting properties of the parent dendrimer, with hole mobilities of ～10?3 cm2/(V s) for solution processed neat films. However, when blended with [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM), the best performing poly(dendrimer) was found to form films that had balanced and relatively high hole/electron mobilities of ～5 × 10?4 cm2/(V s). In contrast, at the same concentration the parent dendrimer:PC70BM blend was found to have a hole mobility of 4 orders of magnitude less than the electron mobility. The balanced hole and electron mobilities for the 6 wt % poly(dendrimer):PC70BM blend led to an absence of second-order bimolecular recombination losses at the maximum power point and resulted in a fill factor of 0.65 and a PCE 2.1% for the devices, which was almost three times higher than the cells composed of the parent dendrimer:PC70BM blends.
关键词： photoinduced hole transfer,charge transport,organic solar cells,hole-transporting poly(dendrimer)s,low donor content
更新于2025-09-23 15:19:57
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Photochemical dynamics under incoherent illumination: Light harvesting in self-assembled molecular J-aggregates
摘要： Transport phenomena in organic, self-assembled molecular J-aggregates have long attracted a great deal of attention due to their potential role in designing novel organic photovoltaic devices. A large number of theoretical and experimental studies have been carried out describing excitonic energy transfer in J-aggregates under the assumption that excitons are induced by a coherent laser-light source or initialized by a localized excitation on a particular chromophore. However, these assumptions may not provide an accurate description to assess the efficiency of J-aggregates, particularly as building blocks of organic solar cells. Under natural conditions, J-aggregates would be subjected to an incoherent source of light (as is sunlight), which would illuminate the whole photosynthetic complex rather than a single molecule. In this work, we present the first study of the efficiency of photosynthetic energy transport in self-assembled molecular aggregates under incoherent sunlight illumination. By making use of a minimalistic model of a cyanine dye J-aggregate, we demonstrate that long-range transport efficiency is enhanced when exciting the aggregate with incoherent light. Our results thus support the conclusion that J-aggregates are, indeed, excellent candidates for devices where efficient long-range incoherently induced exciton transport is desired, such as in highly efficient organic solar cells.
关键词： incoherent illumination,exciton transport,organic solar cells,J-aggregates,photosynthetic energy transport
更新于2025-09-23 15:19:57
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Over 15% Efficiency in Ternary Organic Solar Cells by Enhanced Charge Transport and Reduced Energy Loss
摘要： In this study, an efficient ternary bulk-heterojunction (BHJ) organic solar cell (OSC) is demonstrated by incorporating two acceptors, PC61BM and ITC6-4F with a polymer donor (PM6). It reveals that the addition of PC61BM not only enhances the electron mobility of the derived BHJ blend but also facilitates the exciton dissociation, resulting in a more balanced charge transport alongside with reduced trap-assisted charge recombination. Consequently, as compared to the pristine PM6:ITC6-4F device, the optimal ternary OSC is revealed to deliver an improved power conversion efficiency (PCE) of 15.11% with boosted JSC, VOC and FF simultaneously. The resultant VOC and FF are among the highest values recorded in the literature for the ternary OSCs with PCE exceeding 15%. This result thus suggests that besides improving the charge transport characteristics in devices, incorporating fullerene derivative as part of the acceptor can also improve the resultant VOC, which can reduce the energy loss to realize efficient organic photovoltaic.
关键词： energy transfer,charge transport,fullerene derivative acceptor,open circuit voltage,ternary organic solar cells
更新于2025-09-23 15:19:57
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Delocalization boosts charge separation in organic solar cells
摘要： Organic solar cells (OSCs) utilizing π-conjugated polymers have attracted widespread interest over the past three decades because of their potential advantages, including low weight, thin film flexibility, and low-cost manufacturing. However, their power conversion efficiency (PCE) has been far below that of inorganic analogs. Geminate recombination of charge transfer excitons is a major loss process in OSCs. This paper reviews our recent progress in using transient absorption spectroscopy to understand geminate recombination in bulk heterojunction OSCs, including the impact of polymer crystallinity on charge generation and dissociation mechanisms in nonfullerene acceptor-based OSCs. The first example of a high PCE with a small photon energy loss is also presented. The importance of delocalization of the charge wave function to suppress geminate recombination is highlighted by this focus review.
关键词： Polymer crystallinity,Power conversion efficiency,Organic solar cells,Transient absorption spectroscopy,Dissociation mechanisms,Photon energy loss,π-conjugated polymers,Charge generation,Nonfullerene acceptor,Geminate recombination
更新于2025-09-23 15:19:57