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Electrona??Deficient and Quinoid Central Unit Engineering for Unfused Ringa??Based A <sub/>1</sub> a??Da??A <sub/>2</sub> a??Da??A <sub/>1</sub> a??Type Acceptor Enables High Performance Nonfullerene Polymer Solar Cells with High <i>V</i> <sub/>oc</sub> and PCE Simultaneously
摘要： Here, a pair of A1–D–A2–D–A1 unfused ring core-based nonfullerene small molecule acceptors (NF-SMAs), BO2FIDT-4Cl and BT2FIDT-4Cl is synthesized, which possess the same terminals (A1) and indacenodithiophene unit (D), coupling with different fluorinated electron-deficient central unit (difluorobenzoxadiazole or difluorobenzothiadiazole) (A2). BT2FIDT-4Cl exhibits a slightly smaller optical bandgap of 1.56 eV, upshifted highest occupied molecular orbital energy levels, much higher electron mobility, and slightly enhanced molecular packing order in neat thin films than that of BO2FIDT-4Cl. The polymer solar cells (PSCs) based on BT2FIDT-4Cl:PM7 yield the best power conversion efficiency (PCE) of 12.5% with a Voc of 0.97 V, which is higher than that of BO2FIDT-4Cl-based devices (PCE of 10.4%). The results demonstrate that the subtle modification of A2 unit would result in lower trap-assisted recombination, more favorable morphology features, and more balanced electron and hole mobility in the PM7:BT2FIDT-4Cl blend films. It is worth mentioning that the PCE of 12.5% is the highest value in nonfused ring NF-SMA-based binary PSCs with high Voc over 0.90 V. These results suggest that appropriate modulation of the quinoid electron-deficient central unit is an effective approach to construct highly efficient unfused ring NF-SMAs to boost PCE and Voc simultaneously.
关键词： nonfullerene organic solar cells,unfused ring small molecular acceptors,polymer solar cells,electron-deficient central segment,difluorobenzothiadiazole
更新于2025-09-23 15:21:01
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Over 14% Efficiency Nonfullerene All-Small-Molecule Organic Solar Cells Enabled by Improving the Ordering of Molecular Donor via Side-Chains Engineering
摘要： Improving the short current density (Jsc) is a big challenge for gaining highly efficient nonfullerene all-small-molecule organic solar cells (NFASM-OSCs). Herein, a novel small molecular donor, BT-2F which is derived from previously reported BTEC-2F, was designed and synthesized. The shortened alkyl-chains with higher regularity endow BT-2F with more ordered packing arrangement and more compact lamellar stacking as evidenced by the characterization of differential scanning calorimetry and grazing incidence X-ray diffraction. By blending BT-2F with Y6 or N3, BT-2F based devices showed impressive power conversion efficiencies (PCEs) of 13.80% and 14.09% respectively, much higher than the reported PCE of 13.34% for BTEC-2F:Y6. Besides, the efficiency of 14.09% is also among the highest PCE value reported so far for NFASM-OSCs. The distinctly improved Jsc devoted major efforts to enhancing the PCE values, meanwhile both BT-2F:Y6 and BT-2F:N3 still keep the high fill factors over 70%, which are ascribed to the good balance between high crystallinity and proper phase separation.
关键词： Morphology control,Crystallinity,Highly efficient nonfullerene organic solar cells,Molecular packing arrangement,Molecule design
更新于2025-09-23 15:19:57
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Flexible Alla??Solutiona??Processed Organic Solar Cells with Higha??Performance Nonfullerene Active Layers
摘要： All-solution-processed organic solar cells (from the bottom substrate to the top electrode) are highly desirable for low-cost and ubiquitous applications. However, it is still challenging to fabricate efficient all-solution-processed organic solar cells with a high-performance nonfullerene (NF) active layer. Issues of charge extraction and wetting are persistent at the interface between the nonfullerene active layer and the printable top electrode (PEDOT:PSS). In this work, efficient all-solution-processed NF organic solar cells (from the bottom substrate to the top electrode) are reported via the adoption of a layer of hydrogen molybdenum bronze (HXMoO3) between the active layer and the PEDOT:PSS. The dual functions of HXMoO3 include: 1) its deep Fermi level of ?5.44 eV can effectively extract holes from the active layer; and 2) the wetting issues of the PEDOT:PSS on the hydrophobic surface of the NF active layer can be solved. Importantly, fine control of the HXMoO3 composition during the synthesis is critical in obtaining processing orthogonality between HXMoO3 and the PEDOT:PSS. Flexible all-solution-processed NF organic solar cells with power conversion efficiencies of 11.9% and 10.3% are obtained for solar cells with an area of 0.04 and 1 cm2, respectively.
关键词： nonfullerene organic solar cells,all-solution-processed,hydrogen molybdenum bronze,charge extraction,wetting
更新于2025-09-23 15:19:57
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17% Efficient Organic Solar Cells Based on Liquid Exfoliated WS <sub/>2</sub> as a Replacement for PEDOT:PSS
摘要： The application of liquid-exfoliated 2D transition metal disulfides (TMDs) as the hole transport layers (HTLs) in nonfullerene-based organic solar cells is reported. It is shown that solution processing of few-layer WS2 or MoS2 suspensions directly onto transparent indium tin oxide (ITO) electrodes changes their work function without the need for any further treatment. HTLs comprising WS2 are found to exhibit higher uniformity on ITO than those of MoS2 and consistently yield solar cells with superior power conversion efficiency (PCE), improved fill factor (FF), enhanced short-circuit current (JSC), and lower series resistance than devices based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and MoS2. Cells based on the ternary bulk-heterojunction PBDB-T-2F:Y6:PC71BM with WS2 as the HTL exhibit the highest PCE of 17%, with an FF of 78%, open-circuit voltage of 0.84 V, and a JSC of 26 mA cm?2. Analysis of the cells’ optical and carrier recombination characteristics indicates that the enhanced performance is most likely attributed to a combination of favorable photonic structure and reduced bimolecular recombination losses in WS2-based cells. The achieved PCE is the highest reported to date for organic solar cells comprised of 2D charge transport interlayers and highlights the potential of TMDs as inexpensive HTLs for high-efficiency organic photovoltaics.
关键词： liquid exfoliation,2D transition metal disulfides,nonfullerene organic solar cells,hole transport layers,MoS2,WS2
更新于2025-09-19 17:13:59
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A New Wide Bandgap Donor Polymer for Efficient Nonfullerene Organic Solar Cells with a Large Open‐Circuit Voltage
摘要： Significant progress has been made in nonfullerene small molecule acceptors (NF-SMAs) that leads to a consistent increase of power conversion efficiency (PCE) of nonfullerene organic solar cells (NF-OSCs). To achieve better compatibility with high-performance NF-SMAs, the direction of molecular design for donor polymers is toward wide bandgap (WBG), tailored properties, and preferentially ecofriendly processability for device fabrication. Here, a weak acceptor unit, methyl 2,5-dibromo-4-fluorothiophene-3-carboxylate (FE-T), is synthesized and copolymerized with benzo[1,2-b:4,5-b′]-dithiophene (BDT) to afford a series of nonhalogenated solvent processable WBG polymers P1-P3 with a distinct side chain on FE-T. The incorporation of FE-T leads to polymers with a deep highest occupied molecular orbital (HOMO) level of ?5.60?5.70 eV, a complementary absorption to NF-SMAs, and a planar molecular conformation. When combined with the narrow bandgap acceptor ITIC-Th, the solar cell based on P1 with the shortest methyl chain on FE-T achieves a PCE of 11.39% with a large Voc of 1.01 V and a Jsc of 17.89 mA cm?2. Moreover, a PCE of 12.11% is attained for ternary cells based on WBG P1, narrow bandgap PTB7-Th, and acceptor IEICO-4F. These results demonstrate that the new FE-T is a highly promising acceptor unit to construct WBG polymers for efficient NF-OSCs.
关键词： complementary absorption,wide bandgap,donor polymers,nonfullerene organic solar cells,nonhalogenated solvents
更新于2025-09-19 17:13:59
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Influence of Polymer Aggregation and Liquid Immiscibility on Morphology Tuning by Varying Composition in PffBT4Ta??2DT/Nonfullerene Organic Solar Cells
摘要： The temperature-dependent aggregation behavior of PffBT4T polymers used in organic solar cells plays a critical role in the formation of a favorable morphology in fullerene-based devices. However, there is little investigation into the impact of donor/acceptor ratio on morphology tuning, especially for nonfullerene acceptors (NFAs). Herein, the influence of composition on morphology is reported for blends of PffBT4T-2DT with two NFAs, O-IDTBR and O-IDFBR. The monotectic phase behavior inferred from differential scanning calorimetry provides qualitative insight into the interplay between solid–liquid and liquid–liquid demixing. Transient absorption spectroscopy suggests that geminate recombination dominates charge decay and that the decay rate is insensitive to composition, corroborated by negligible changes in open-circuit voltage. Exciton lifetimes are also insensitive to composition, which is attributed to the signal being dominated by acceptor excitons which are formed and decay in domains of similar size and purity irrespective of composition. A hierarchical morphology is observed, where the composition dependence of size scales and scattering intensity from resonant soft X-ray scattering (R-SoXS) is dominated by variations in volume fractions of polymer/polymer-rich domains. Results suggest an optimal morphology where polymer crystallite size and connectivity are balanced, ensuring a high probability of hole extraction via such domains.
关键词： PffBT4T-2DT,nonfullerene organic solar cells,liquid immiscibility,O-IDTBR,polymer aggregation,O-IDFBR,morphology tuning
更新于2025-09-16 10:30:52
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Solution-Processable All-Small-Molecule for High-Performance Nonfullerene Organic Solar Cells with High Crystallinity Acceptor
摘要： In this work, two small molecule acceptors (IDIC and IDIC-4F) with different crystallinity and energy level have been successfully applied in nonfullerene-based all-small molecule organic solar cells (NFASM-OSCs). The donor of DFDT(DPP)2 was chosen because of complementary absorption with IDIC and IDIC-4F. As acceptor, IDIC-4F exhibited a higher PCE than IDIC due to better crystallinity. This work not only shows us how to balance the relationship between Voc and Jsc, but also suggests us how to get a good phase separation morphology. Moreover, Increased crystallinity helps to inhibit bimolecular recombination and increase charge mobility. By optimizing device preparation conditions, the best PCE of 9.43% for DFDT(DPP)2 : IDIC-4F as active layer was achieved with excitable Jsc (16.83 mA cm-2) and FF (0.65). The FF and Jsc of resultant device show a significant increased which is among the top efficiencies based on DPP as terminal acceptor groups of NFSM-OSCs reported in document up to now.
关键词： crystallinity,small molecule acceptors,phase separation morphology,nonfullerene organic solar cells,charge mobility
更新于2025-09-11 14:15:04
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Chalcogen‐Fused Perylene Diimides‐Based Non‐Fullerene Acceptors for High Performance Organic Solar Cells: Insight into the Effect of O, S and Se
摘要： Three perylene diimide tetramers annulated by oxygen (O), sulfur (S) and selenium (Se), named as SF-4PDI-O, SF-4PDI-S and SF-4PDI-Se, are designed, synthesized and paired with polymeric donor PDBT-T1 to construct OSCs. The heteroatoms’ effect on photoelectric properties, chemical geometry, charge transport, active-layer morphology, and photovoltaic performance are investigated in detail. These PDI acceptors exhibit similar absorption profile; while HOMOs and LUMOs are simultaneously upshifted when heteroatoms are altered from O, S to Se due to the gradually weakening electronegativity. Alongside PDBT-T1, SF-4PDI-O achieved the outstanding PCE of 8.904% with a high FF of 0.706, outcompeting its S-annulated and Se-annulated counterparts. The superiority of PDBT-T1: SF-4PDI-O system lies in stronger crystallinity, more balanced hole and electron mobilities, weaker bimolecular recombination, coupled with more efficient charge transfer and collection. These results shed light on the invention of high-performance PDI acceptors by oxygen-decorated methodology.
关键词： chalcogen,nonfullerene,organic solar cells,perylene diimides,small molecule acceptors
更新于2025-09-11 14:15:04