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- 摘要
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Significant influence of the benzothiophene ring substitution position on the photovoltaic performance of benzodithiophene-based donor polymers
摘要： In order to investigate the e?ects of the substitution position on the photovoltaic performance of donor polymers, two benzothiophene ring substituted benzo(1,2-b:4,5-b0)dithiophene (BDT)-based conjugated polymers (PBDTBTs-BDD and PBDTTBs-BDD) are designed and synthesized. The variation in the substitution position has small influences on the photophysical properties but has a great e?ect on the intramolecular p–p stack structure, charge transport and photovoltaic properties. PBDTBTs-BDD (with the 6-position of the benzothiophene substituent) exhibited a smaller p–p stacking distance of 3.67 ? compared to 4.11 ? seen for PBDTTBs-BDD (with the 2-position of the benzothiophene substituent). And the charge mobilities of PBDTBTs-BDD-based devices are higher and more balanced than those of PBDTTBs-BDD-based devices, which are highly beneficial for reducing recombination of free carriers and then lead to a higher short-circuit current density (JSC) and fill factor (FF) of devices. With ITIC or Y6 as non-fullerene acceptors, PBDTBTs-BDD-based devices exhibit power conversion efficiencies (PCE) of 7.76% and 12.07%, respectively, which are higher than those of PBDTTBs-BDD-based devices (5.04% and 5.81%). This work demonstrates that the photovoltaic properties of donor polymers can be highly tunable through slight modifications of their side chain structures.
关键词： benzothiophene,donor polymers,photovoltaic performance,power conversion efficiencies,non-fullerene acceptors
更新于2025-09-19 17:13:59
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Nonfullerene acceptors with an N-annulated perylene core and two perylene diimide units for efficient organic solar cells
摘要： We have designed and synthesized a series of perylene based A-D-A type chromophores, which are composed of two electron deficient perylene diimides (PDI) and one electron rich N-annulated perylene (NP). By virtue of the bi-axial rigid skeleton of the flat NP unit, the intermolecular aggregation is efficiently suppressed, leading to a very small red-shift of absorption being observed in going from solutions to films. In addition, the molar extinction coefficients have been significantly elevated in case of sulfur or selenium annulation at the bay positions of the PDI units. Quantum calculation is employed for the geometry optimization to further understand the contributions of different excitations to the UV-vis absorption spectra. Morphology studies demonstrate that the twisted conformations of these acceptors are favorable for the formation of suitable phase separation in the as-cast films. The heteroatom annulation could force the PDI plane to take on a more planar conformation, which is favorable to have closer π?π stacking for efficient electron transportation. Finally, the as-cast devices based on PBDB-T:NP-diPDI-Se display a power conversion efficiency (PCE) of 6.25% with a Voc of 0.98 V, a Jsc of 11.73 mA/cm2 and an FF of 54.13%.
关键词： N-annulated perylene,Nonfullerene acceptors,Organic solar cells,Power conversion efficiency,Perylene diimide
更新于2025-09-19 17:13:59
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Effect of Side Substituents Incorporated into <i>??</i> a??Bridges of Quinoxalinea??Based Sensitizers for Dyea??Sensitized Solar Cells
摘要： ZW003, has been synthesized and applied in dye-sensitized solar cells (DSSCs). Both dyes have broad absorption and large molar absorption coefficients. The sensitizer with the HQ core effectively restrains intermolecular aggregation owing to steric hindrance of numerous alkyl chains. A thienyl unit with or without a hexyl branch is used as a π-bridge. Incorporation of only thienyl groups as a π-bridge into the sensitizer increases the dye-loading amount on TiO2 film owing to the smaller molecular size. Using the ZW002 dye with the Co (II/III) redox couple results in DSSCs that exhibits a high photovoltaic conversion efficiency of 8.23% and short-circuit current density (Jsc) of 12.43 mA cm?2, an open-circuit voltage (Voc) of 960 mV, and a fill factor (FF) of 0.69. Although ZW003 shows a wider absorption range than that of ZW002, the two additional phenyl groups on the quinoxaline unit contributes to poorer performance (PCE of 7.43%) due to more serious dye aggregation.
关键词： Quinoxaline,Additional acceptors,Intermolecular aggregation,Dye-loading amount,Dye-sensitized solar cells
更新于2025-09-19 17:13:59
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Ultrafast Hole Transfer and Carrier Transport Controlled by Nanoscale-Phase Morphology in Nonfullerene Organic Solar Cells
摘要： Nonfullerene acceptors (NFAs) have attracted great attention in high-efficiency organic solar cells (OSCs). While the effect of molecular properties including structures and energetics on charge transfer have been extensively investigated, the effect of macroscopic phase properties is yet to be revealed. Here we have performed a correlation study of the nanoscale phase morphology on photoexcited hole transfer (HT) process and photovoltaic performance, by combing ultrafast spectroscopy with high temporal resolution and photo-induced force microscopy (PiFM) with high spatial and chemical resolution. In PM6/IT-4F, we observe a biphasic HT behavior with a minor ultrafast (< 100 fs) interfacial process and a major diffusion mediated HT process till ~ 100 ps, which depends on phase segregation strongly. Because of the interplay between charge transfer and transport, a compromised domain size of 20 ~ 30 nm for NFAs shows best performance. This study highlights the critical role of phase morphology in high-efficiency OSCs.
关键词： photo-induced force microscopy,phase morphology,ultrafast spectroscopy,organic solar cells,hole transfer,Nonfullerene acceptors
更新于2025-09-19 17:13:59
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Trifluoromethylation Enables a 3D Interpenetrated Low-Band-Gap Acceptor for Efficient Organic Solar Cells
摘要： Herein, tri?uoromethylation has proven to be an effective strategy for ultra-narrow band-gap NFAs. A PCE of 15.59% is achieved from BTIC-CF3-g-based devices, which is the highest value in reported ultra-narrow band-gap acceptors. A ternary device with 16.50% ef?ciency is also obtained, resulting from its red-shifted absorption. Meanwhile, the single-crystal structure of BTIC-CF3-g has been successfully presented, which gives a deep understanding of the solid-state molecular packings in these highly ef?cient acceptors.
关键词： ultra-narrow band-gap,nonfullerene acceptors,tri?uoromethylation,power conversion efficiency,organic solar cells
更新于2025-09-19 17:13:59
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Bandgap Tailored Nonfullerene Acceptors for Low-Energy-Loss Near-Infrared Organic Photovoltaics
摘要： A series of A?π?D?π–A type nonfullerene acceptors (NFAs) was designed and synthesized with the goal of optimizing light absorption and energy losses in near-infrared (NIR) organic solar cells (OSCs) principally through the use of side chain engineering. Specific molecules include p-IO1, o-IO1, p-IO2, and o-IO2 with optical bandgaps of 1.34 eV, 1.28 eV, 1.24 eV, and 1.20 eV, respectively. Manipulating the optoelectronic properties and intermolecular organization by substituting bulky phenylhexyl (p-) for linear octyl chains (o-) and replacing bisalkoxy (-O2) with alkyl-alkoxy combination (-O1) allows one to target energy bandgaps and achieve a favorable bulk heterojunction morphology when in the presence of the donor polymer PTB7-Th. Solar cells based on o-IO1 and PTB7-Th exhibit an optimal power conversion efficiency of 13.1%. The excellent photovoltaic performance obtained with the o-IO1 acceptor can be attributed to a short-circuit current of 26.3 mA cm?2 and energy losses on the order of 0.54 eV. These results further highlight how side chain engineering is a straightforward strategy to tune the molecular design of n-type molecular semiconductors, particularly in the context of near-infrared high efficiency organic photovoltaics.
关键词： side chain engineering,nonfullerene acceptors,power conversion efficiency,organic solar cells,near-infrared
更新于2025-09-19 17:13:59
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Solar-Powered Artificial Photosynthesis Coupled with Organic Synthesis
摘要： Organic photovoltaics (OPVs) have attracted much attention because of the advantages in low-cost and large-area fabrication and the great potentials in achieving flexible and semi-transparent devices. However, compared with inorganic and perovskite solar cells, OPVs show relatively low photoelectric conversion efficiencies, which is admittedly attributed to intrinsically low dielectric constants of organic materials resulting in large energy losses. With the rapid development of fused-ring electron acceptors especially with an acceptor (A)-donor (D)-acceptor (A) arrangement, PCEs of OPV devices quickly surpassed 12% and even reached 16% in a very short period, in quite a few of which the Elosss are less than 0.6 eV. Although it is common for inorganic or perovskite solar cells, high-performance OPVs with the Elosss less than 0.5 eV are quite rare up to date, which means that the Eloss is still the key factor that limits the photovoltaic efficiency of the OPV technique. Nonetheless, progresses in the development of efficient OPVs by reducing the Eloss to less than 0.5 eV have been made in the past few years.
关键词： Photovoltaic efficiency,Energy loss,Organic solar cells,Non-fullerene acceptors
更新于2025-09-19 17:13:59
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On the absence of triplet exciton loss pathways in non-fullerene acceptor based organic solar cells
摘要： We investigate the viability of highly efficient organic solar cells (OSCs) based on non-fullerene acceptors (NFA) by taking into consideration efficiency loss channels and stability issues caused by triplet excitons (TE) formation. OSCs based on a blend of the conjugated donor polymer PBDB-T and ITIC as acceptor were fabricated and investigated with electrical, optical and spin-sensitive methods. The spin-Hamiltonian parameters of molecular TEs and charge transfer TEs in ITIC e.g., zero-field splitting and charge distribution, were calculated by Density Functional Theory (DFT) modelling. In addition, the energetic model describing the photophysical processes in the donor-acceptor blend was derived. Spin-sensitive photoluminescence measurements prove the formation of charge transfer (CT) states in the blend and the formation of TEs in the pure materials and the blend. However, no molecular TE signal is observed in the completed devices under working conditions by spin-sensitive electrical measurements. The absence of a molecular triplet state population allows to eliminate a charge carrier loss channel and irreversible photooxidation facilitated by long-lived triplet states. These results correlate well with the high power conversion efficiency of the PBDB-T:ITIC-based OSCs and their high stability.
关键词： triplet excitons,Density Functional Theory,organic solar cells,non-fullerene acceptors,photoluminescence detected magnetic resonance,electrically detected magnetic resonance
更新于2025-09-19 17:13:59
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Exciplexa??Based Organic Lighta??Emitting Diodes with Neara??Infrared Emission
摘要： Near-infrared exciplex can weaken molecular design difficulties, and has the advantage of easy bathochromic-shift spectra via selecting the suitable electron donors and acceptors. In this contribution, exciplex is applied to fabricate near-infrared (NIR) organic light-emitting diodes (OLEDs) incorporating a synthesized fluorescent material 3-([1,1″:3′,1″-terphenyl]-5′-yl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile (APDC-tPh) and a commercially available material 4,4′,4″-tris(carbazol-9-yl)triphenylamine (TCTA). The device having a mixed TCTA:APDC-tPh as an emitting layer shows a 730 nm NIR emission with a maximum external quantum efficiency (EQE) of about 0.1%, while the device having 2-[4-(diphenylamino)phenyl]-10,10-dioxide-9H-thioxanthen-9-one (TXO-TPA):APDC-tPh as the emitting layer exhibits an emission peak of 704 nm with a maximum EQE of 1.27%. These results prove the feasibility of fabricating the efficient exciplex-based NIR OLEDs.
关键词： donors and acceptors,near-infrared OLEDs,exciplexes,bathochromic shifts
更新于2025-09-19 17:13:59
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Evaporation‐Free Nonfullerene Flexible Organic Solar Cell Modules Manufactured by An All‐Solution Process
摘要： To ensure laboratory-to-industry transfer of next-generation energy harvesting organic solar cells (OSCs), it is necessary to develop flexible OSC modules that can be produced on a continuous roll-to-roll basis and to apply an all-solution process. In this study, nonfullerene acceptors (NFAs)-based donor polymer, SMD2, is newly designed and synthesized to continuously fabricate high-performance flexible OSC modules. Also, multifunctional hole transport layers (HTLs), WO3/HTL solar bilayer HTLs, are developed and applied via an all-solution process called “ProcessOne” into inverted structure. SMD2, the donor terpolymer, has a deep highest occupied molecular orbital (HOMO) level and can achieve a power conversion efficiency (PCE) of 11.3% with NFAs without any pre-/post-treatment because of its optimal balance between crystallinity and miscibility. Furthermore, the integration of multifunctional HTLs enables the recovery of the drop in open circuit voltage (VOC) caused by a mismatch in energy levels between the deep HOMO level of the NFAs-based bulk-heterojunction layer and the solution-processed HTLs. Also, the photostability under ultraviolet-exposure necessary for “ProcessOne” is greatly improved because of the integration of multifunctional HTLs. Consequently, because of the synergistic effects of these approaches, the flexible OSC modules fabricated in an industrial production line have a PCE of 5.25% (Pmax = 419.6 mW) on an active area of 80 cm2.
关键词： roll-to-roll process,all-solution process,flexible modules,nonfullerene acceptors,organic solar cells
更新于2025-09-19 17:13:59