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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
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Thienyl Sidechain Substitution and Backbone Fluorination of Benzodithiophene-Based Donor Polymers Concertedly Minimize Carrier Losses in ITIC-Based Organic Solar Cells
摘要： Non-fullerene acceptor (NFA) based organic solar cells have outperformed fullerene-based devices, yet their photophysics is less well understood. Herein, changes in the donor polymer backbone side-chain substitution and backbone fluorination in benzodithiophene (BDT)-thiophene copolymers are linked to the photophysical processes and performance of bulk heterojunction (BHJ) solar cells, using ITIC as NFA. Increased geminate recombination is observed when the donor polymer is alkoxy-substituted in conjunction with faster non-geminate recombination of free charges, limiting both the short circuit current and device fill factor. In contrast, thienyl-substitution reduces geminate recombination, albeit non-geminate recombination remains significant, leading to improved short circuit current density, yet not fill factor. Only the combination of thienyl-substitution and polymer backbone fluorination yields both efficient charge separation and significantly reduced non-geminate recombination, resulting in fill factors (FFs) in excess of 60 %. Time-delayed collection field measurements ascertain that charge generation is field-independent in the thienyl-substituted donor polymer:ITIC systems, while weakly field dependent in the alkoxy-substitued polymer:ITIC blend, indicating the low FFs are primarily caused by non-geminate recombination. This work provides insight into the interplay of donor polymer structure, BHJ photophysics, and device performance for a prototypical NFA, namely ITIC. More specifically, it links the donor polymer chemical structure to quantifiable changes of kinetic parameters and the yield of individual processes in ITIC-based BHJ blends.
关键词： non-fullerene acceptor,ultrafast spectroscopy,bulk heterojunction,charge generation,organic photovoltaics
更新于2025-09-23 15:19:57
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A Trifluoromethyl Group Modified Non-fullerene Acceptor Towards Improved Power Conversion Efficiency Over 13% in Polymer Solar Cells
摘要： Herein, we report a new molecule structure modification strategy for non-fullerene small molecule electron acceptors (NFAs) for solar cells through trifluoromethylation of end-capping groups. The synthesized trifluoromethylated acceptor ITCF3 exhibits narrower band gap, stronger light absorption, lower molecular energy levels and better electron transport property comparing to the reference NFA without trifluoromethyl group (ITIC). Bulk heterojunction solar cells based on ITCF3 combined with PM6 polymer donor exhibit a significantly improved power conversion efficiency of 13.3% comparing with ITIC-based device (8.4%). This work reveals great potential of trifluoromethylation in design of efficient photovoltaic acceptor materials.
关键词： power conversion efficiency,non-fullerene acceptor,trifluoromethyl group,organic solar cell,polymer
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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With PBDB-T as the Donor, the PCE of Non-Fullerene Organic Solar Cells Based on Small Molecule INTIC Increased by 52.4%
摘要： At present, most high-performance non-fullerene materials are centered on fused rings. With the increase in the number of fused rings, production costs and production difficulties increase. Compared with other non-fullerenes, small molecule INTIC has the advantages of easy synthesis and strong and wide infrared absorption. According to our previous report, the maximum power conversion efficiency (PCE) of an organic solar cell using PTB7-Th:INTIC as the active layer was 7.27%. In this work, other polymers, PTB7, PBDB-T and PBDB-T-2F, as the donor materials, with INTIC as the acceptor, are selected to fabricate cells with the same structure to optimize their photovoltaic performance. The experimental results show that the optimal PCE of PBDB-T:INTIC based organic solar cells is 11.08%, which, thanks to the open voltage (VOC) increases from 0.80 V to 0.84 V, the short circuit current (JSC) increases from 15.32 mA/cm2 to 19.42 mA/cm2 and the fill factor (FF) increases from 60.08% to 67.89%, then a 52.4% improvement in PCE is the result, compared with the devices based on PTB7-Th:INTIC. This is because the PBDB-T:INTIC system has better carrier dissociation and extraction, carrier transportation and higher carrier mobility.
关键词： polymer solar cells (PSCs),synthesize easily,carrier transportation and extraction,carrier mobility,strong and wide infrared absorption,non-fullerene small molecule acceptor
更新于2025-09-23 15:19:57