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Barrier-Free Charge Separation Enabled by Electronic Polarization in High-Efficiency Non-Fullerene Organic Solar Cells
摘要： The separation of charge-transfer (CT) states into free charges at the donor/acceptor (D/A) interfaces plays a central role for organic solar cells (OSCs). Because of strong Coulomb attraction, the separation mechanisms are elusive, particularly for the high-efficiency non-fullerene (NF) OSCs with low exciton-dissociation driving forces. Here, we demonstrate that the Coulomb barriers can be substantially overcome by electronic polarization for OSCs based on a series of A-D-A acceptors (ITIC, IT-4F, and Y6). In contrast to fullerene-based D/A heterojunctions, the polarization energies for both donor holes and acceptor electrons are remarkably increased from the interfaces to pure regions in the NF heterojunctions owing to strong stabilization on electrons but destabilization on holes by electrostatic interactions in the A-D-A acceptors. Especially, upon incorporating fluorine substituents and electron-poor cores to ITIC, the increased polarization energies can completely compensate the Coulomb attraction in the IT-4F and Y6 based Heterojunctions, leading to barrierless charge separation.
关键词： electrostatic interaction,induction effect,charge generation,organic photovoltaics,non-fullerene acceptors
更新于2025-09-23 15:19:57
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Constructing Higha??Performance Organic Photovoltaics via Emerging Nona??Fullerene Acceptors and Tandema??Junction Structure
摘要： In consideration of the unique advantages of new non-fullerene acceptors and the tandem-junction structure, organic photovoltaics (OPVs) based on them are very promising. Studies related to this emerging area began in 2016 with achieved power conversion efficiencies (PCEs) of 8–10%, which have now been boosted to 17%. In this essay, the construction of high-performance OPVs is discussed, with a focus on combining the advantages of new non-fullerene acceptors and the tandem-junction structure. In order to achieve higher PCEs, methods to enable high short-circuit current density, open-circuit voltage, and fill factor are discussed. In addition, the stability and reproducibility of high-efficiency OPVs are also addressed. Herein, it is forecast that the new non-fullerene acceptors-based tandem-junction OPVs will become the next big wave in the field and achieve high PCEs over 20% in the near future. Some promising research directions on this emerging hot topic are proposed which may further push the field into the 25% high efficiency era and considerably advance the technology beyond laboratory research.
关键词： non-fullerene acceptors,organic solar cells,organic photovoltaics,tandem solar cells
更新于2025-09-23 15:19:57
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Tuning the optoelectronic properties of Benzo Thiophene (BT-CIC) based Non-Fullerene Acceptor Organic Solar Cell
摘要： Organic solar cells have become a center of attention in the field of research and technology due to its remarkable features. In current research work, we designed Benzo Thiophene (BT-CIC) based non-fullerene acceptor organic solar cell having A-D-A novel structure. The designed structures D1-D4 were derived from BT-CIC (non-fullerene acceptor) by replacing 2-(5,6-dichloro-2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene)acetonitrile of reference molecule R with different electron withdrawing end-capper acceptor moieties. The e?ect of end acceptor groups on absorption, energy level, charge transport, morphology, and photovoltaic properties of the designed molecules (D1-D4) were investigated by TD-DFT B3LYP/6-31G basic level of theory and compared with reference molecule R. Among all novel structures, D3 exhibited maximum absorption (λmax) of 701.7nm and 755.2 nm in gaseous state and chloroform respectively. The red shift in D3 was due presence of strong electron withdrawing acceptor moiety and more extended conjugation as compared to other structures. D3 also displayed lowest values of energy band gap (1.97 eV), λe (0.0063 eV) and λh (0.0099 eV) and which signify its ease electron mobility. Lowest value of binding energy 1.20 eV of D3 suggested that this molecule could be easily dissociated into charge carriers TDM results revealed that easy exciton dissociation occurred in D3. Overall, designed structure D3 was found to be more effective and efficient acceptor molecule for SMOSCs. The findings provide novel information for the development of non-fullerene acceptors for OPVs.
关键词： theoretical studies,opto-electronic properties,benzothiophene,organic solar cells,Non-Fullerene Acceptor
更新于2025-09-23 15:19:57
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Quantification of Photophysical Processes in Alla??Polymer Bulk Heterojunction Solar Cells
摘要： Combined data of transient optical and electro-optical experiments reveals the efficiency-determining processes in all-polymer solar cells and allows precisely quantifying their yields. For the test system presented here, field-dependent charge separation is shown to limit the fill factor and thus the performance by comparing the experimentally-measured current-voltage characteristics to those reproduced by drift-diffusion simulations using the spectroscopically-determined kinetic parameters.
关键词： all-polymer solar cells,bulk heterojunction,non-fullerene acceptors,transient absorption,organic photovoltaics
更新于2025-09-23 15:19:57
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Employing a Narrow-bandgap Mediator in Ternary Solar Cells for Enhanced Photovoltaic Performance
摘要： Ternary organic solar cells (OSCs) provide a convenient and effective means to further improve the power conversion efficiency (PCE) of binary ones via composition control. However, the role of the third component remains to be explored in specific binary systems. Herein, we report ternary blend solar cells by adding the narrow-bandgap donor PCE10 as the mediator into the PBDB-T:IDTT-T binary blend system. The extended absorption, efficient fluorescence resonance energy transfer, enhanced charge dissociation and induced tighter molecular packing of the ternary blend films enhance the photovoltaic properties of devices and deliver a champion PCE of 10.73% with an impressively high open-circuit voltage (VOC) of 1.03 V. Good miscibility and similar molecular packing behavior of the components guarantee the desired morphology in the ternary blend films, leading to solar cell devices with over 10% PCEs at a range of compositions. Our results suggest ternary systems with properly aligned energy levels and overlapping absorption amongst the components hold great promises to further enhance performance of corresponding binary ones.
关键词： ternary solar cell,energy transfer,induced crystallization property,non-fullerene acceptors,molecular mediator
更新于2025-09-23 15:19:57
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Efficient Exciton Dissociation Enabled by the End Group Modification in Non-Fullerene Acceptors
摘要： For organic photovoltaic (OPV) cells, in order to overcome the larger Coulombic binding energy between holes and electrons, an extra driving force is required for efficient exciton dissociation. Here, we report two non-fullerene acceptors named IO-4H and IO-4F for OPV cells. By employing the polymer PBDB-TF as a donor, PBDB-TF:IO-4H-based device only shows a power conversion efficiency (PCE) of 0.30% with a charge dissociation probability (Pdiss) of 13.3%. On the contrary, PBDB-TF:IO-4F-based device demonstrates a PCE of 7.85%, with a Pdiss of 81.3%. The photoelectric processes demonstrate that both devices have similar charge transport and charge recombination properties. The limitation of photovoltaic performance is the low exciton dissociation efficiency in the PBDB-TF:IO-4H-based device. The theoretical studies show the electrostatic potential (ESP) of IO-4H is negative in the end groups and similar to the ESP of PBDB-TF, while ESP of IO-4F is positive. PBDB-TF and the IO-4F may form a strong intermolecular electric field to assist the exciton dissociation. Our results suggest that increasing the ESP difference between donor and acceptor may be beneficial to promote exciton dissociation, thus improving photovoltaic performance.
关键词： organic photovoltaic,electrostatic potential,power conversion efficiency,exciton dissociation,non-fullerene acceptors
更新于2025-09-23 15:19:57
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Development of Block Copolymers with Poly(3-hexylthiophene) Segments as Compatibilizers in Non-Fullerene Organic Solar Cells
摘要： P3HT-segment-based block copolymers have been reported to deliver an effective compatibilizer function in the P3HT:PC61BM bulk-heterojunction (BHJ) system to simultaneously improve performance and stability. However, as limited by the deficient optophysic properties of the P3HT:PC61BM system, the resultant power conversion efficiency (PCE) of compatibilizer-mediated devices is low despite the optimized chemical structures of the P3HT-segment-based block copolymers. To better shed light on such compatibilizer effect, the compatibilizer function of the P3HT-segment-based block copolymers is herein investigated in the emerging non-fullerene acceptor (NFA)-based BHJ systems. A P3HT analogue, poly[(4,4′-bis(2-butyloctoxycarbonyl-[2,2′-bithiophene]-5,5-diyl)-alt-(2,2′-bithiophene-5,5′-diyl)] (PDCBT), is used as the polymer donor since it shares the same backbone as P3HT to afford good compatibility with the P3HT-segment-based block copolymers and it has been proven to deliver a higher PCE than P3HT in the NFA BHJ systems. The P3HT-segment-based block copolymers (P1-P4) are manifested to offer similar compatibilizer function for the PDCBT-based NFA BHJ systems and the importance of their structural design is also revealed. As a result, addition of P4 delivers the largest enhancement in PCE: from 5.30% to 7.11% for the PDCBT:ITIC blend and from 6.21% to 8.04% for the PDCBT:IT-M blend. Moreover, it can also enhance device’s thermal stability, which can maintain 77% of initial PCE after annealing at 85 oC for 120 h (for the PDCBT:ITIC blend), outperforming the pristine binary device (66% preservation). More importantly, all the compatibilizer-mediated device exhibits an improved Voc. Such reduced potential loss can be attributed to the improved interfacial compatibility between the photoactive components, the most important function of a compatibilizer.
关键词： compatibilizer,poly(3-hexylthiophene) segment,non-fullerene acceptor,organic solar cells,Block copolymers
更新于2025-09-23 15:19:57
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Higher open circuit voltage caused by chlorinated polymers endows improved efficiency of binary organic solar cell
摘要： Organic solar cell (OSC) has achieved great progress in the past few years. Power conversion efficiency (PCE) has stepped into a new stage due to the evolution of non-fullerene acceptors (NFAs). The gap between lowest unoccupied molecular orbit of acceptor and highest occupied molecular orbit of donor (|ELUMOA-EHOMOD|) is proportional to the value of open circuit voltage (VOC). Applying two similar polymeric donors with different energy levels offers possibility of changing VOC without significantly impacting short circuit current (JSC) and fill factor (FF). Here we chose halogenated polymers PM6 and PM7 as donors to cope with a newly design asymmetric molecule TPIC-4Cl derived from IT-4Cl. As a result, the PM7:TPIC-4Cl device achieved a PCE of 15.1% than its PM6:TPIC-4Cl counterparts (14.4%), wherein the improvement of VOC from 0.855V to 0.885V contributed most. Our work proves the feasibility of improving photovoltaic performance of NFA OSCs by utilizing polymeric donors with similar structure yet different HOMOs. Besides, the PCE over 15% of OSCs involving no Y6 or its derivatives sheds light on another direction of OSC research.
关键词： gap tuning,power conversion efficiency,non-fullerene acceptor
更新于2025-09-23 15:19:57
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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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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