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Improved charge transfer, mobility and morphology for high performance panchromatic organic photodetectors by adding PC71BM in P3HT:IEICO-4F
摘要： High performance of panchromatic organic photodetectors (OPDs) with a wide spectral response ranged from 300 to 1000 nm were realized through adding [6,6]-phenyl-C71-butyric acid methylester (PC71BM) fullerene as an electron acceptor into the polymer donor of poly (3-hexylthiophene) (P3HT) and the small molecular non-fullerene acceptor of 2, 2′-((2Z,2′Z)-(((4, 4, 9, 9-tetrakis(4-hexylphenyl)-4, 9-dihydro-sindaceno[1, 2-b:5, 6-b′] dithiophene-2, 7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5, 2-diyl))bis-(methanylylidene))bis(5, 6-di?uoro-3-oxo-2, 3-dihydro-1H-indene-2, 1-diylidene))dimalononitrile (IEICO-4F) host system. The fabricated OPD exhibited a high detectivity (D*) of 1.35 × 1012 Jones at 805 nm by adding 10 wt% PC71BM, which is 1.5 folds higher than it from the control system. The improved performance was mainly attributed to the increased light absorption in the short wavelength range and cascade energy level alignment, which is responsible for the e?cient light harvesting and exciton utilization. Furthermore, the active layer morphology was optimized by adjusting the ratio of PC71BM acceptor, which e?ciently enhances charge transport and mobility of the device as well as suppress bimolecular recombination. This work indicates that adding fullerene into non-fullerene system plays a positive e?ect on the device performance of panchromatic OPDs.
关键词： Film morphology,Charge mobility,Non-fullerene and fullerene acceptors,Panchromatic organic photodetector,Charge transfer
更新于2025-09-11 14:15:04
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Nonacyclic carbazole-based non-fullerene acceptors enables over 12% efficiency with enhanced stability for organic solar cells
摘要： In this work, a nonacyclic carbazole-cored electron-rich central building block called CZTT and its derivated non-fullerene acceptors (CZTT-IC and CZTT-4F) are designed and synthesized. CZTT-4F with fluorination on the accepting end groups shows significantly down-shifted energy levels and a narrower bandgap as well as a smaller dipole moment under the ground state in comparison to the counterpart CZTT-IC. In the blend films, blends of both fluorinated donor and acceptor (PM6:CZTT-4F) reveal relatively decreased miscibility resulting in better donor/acceptor interpenetrating network with higher domain purity for efficient charge transport. Organic solar cells (OSCs) based on PM6:CZTT-4F blend exhibited a highest power conversion efficiency (PCE) of 12.07% with enhanced thermal and light soaking stability. To the best of our knowledge, this performance is among the highest for carbazole-based OSCs in the literature. The results reveal that the nonacyclic CZTT core is a promising building block for constructing efficient non-fullerene acceptors. More importantly, the relatively decreased miscibility within fluorinated CZTT-based blend film is demonstrated to greatly promote the stability of OSCs.
关键词： stability,nonacyclic carbazole,non-fullerene acceptors,organic solar cells,power conversion efficiency
更新于2025-09-11 14:15:04
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Efficient Organic Solar Cells with a High Open‐Circuit Voltage of 1.34 V
摘要： One of the most important challenges that hinders the power conversion efficiencies (PCEs) of organic solar cells (OSCs) is the modest open-circuit voltages (VOC) due to large energy losses. The large driving force during for charge generation and the non-radiative recombination are the main causes of energy losses. To maximize the VOC of OSCs, herein, we modulate the end-groups and design a non-fullerene acceptor ITCCM-O, which shows a bandgap of 2.0 eV. By blending a polymer donor named J52, the device demonstrates a PCE of 5.5% with an outstanding VOC of 1.34 V, which is the highest value for single-junction OSCs over 5% PCEs. The high VOC is benefited from 1) the negligible driving force for charge transfer, and 2) the suppressed non-radiative recombination loss, as low as 0.22 V.
关键词： energy losses,high voltage,non-fullerene acceptors
更新于2025-09-11 14:15:04
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Backbone Fluorination of Polythiophenes Improves Device Performance of Non-Fullerene Polymer Solar Cells
摘要： Polythiophenes (PTs) are promising donor materials for the industrialization of polymer solar cells (PSCs) due to the merits of easy synthesis, low cost, and large-scale producibility. The rapid progress of non-fullerene acceptors requires the development of new PTs for use in non-fullerene PSCs. In this work, we present a set of PTs with different degree of backbone fluorination (P6T-F00, P6T-F50, P6T-F75, and P6T-F100) to investigate the effect of fluorination on the photovoltaic properties of PTs in non-fullerene PSCs. Upon increasing fluorine content, the PTs tend to have higher crystallinity, higher absorption coefficients, and enhanced relative dielectric constants. When blended with a non-fullerene acceptor EH-IDTBR, the blend films show increased photoluminescence quenching efficiency, reduced charge recombination loss, and extended charge carrier lifetime along with increasing fluorine content of PTs. These positive factors collectively result in dramatically improved power conversion efficiency from 4.3% for P6T-F00:EH-IDTBR to 7.3% for P6T-F100:EH-IDTBR, which is superior to the champion binary non-fullerene PSCs based on P3HT. Our results demonstrate that PTs are promising donor materials for non-fullerene PSCs via backbone fluorination.
关键词： polythiophenes,polymer solar cells,backbone fluorination,dielectric constant,non-fullerene acceptors
更新于2025-09-11 14:15:04
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Efficient non-fullerene polymer solar cells enabled by side-chain conjugated thieno[3,4-c]pyrrole-4,6-dione-based polymer and small molecular acceptors
摘要： The application of non-fullerene (NF) acceptors in bulk-heterojunction (BHJ) polymer solar cells (PSCs) is a promising approach to overcome the inherent drawbacks of fullerene derivatives-based acceptors. In PSCs, complementary absorption as well as matched molecular energy levels between the low bandgap acceptor-donor-acceptor (A-D-A) small molecular acceptor and medium/wide bandgap polymer donor is crucial to achieve high power conversion efficiency (PCE). Alternating polymers based on benzodithiophene (BDT) electron-donating segment and thieno[3,4-c]pyrrole-4,6-dione (TPD) electron-withdrawing segment own medium bandgap and low-lying highest occupied molecular orbital (HOMO) energy level, leading to presentable photovoltaic properties with fullerene derivatives. To probe into the performances of TPD-based polymers in NF-PSCs, two TPD-based polymers containing alkoxy or alkylthienyl modified benzo[1,2-b:4,5-b′]dithiophene (BDT) were synthesized and adopted as electron-donors and blended with A-D-A-type electron-acceptor 2,2′-[[6,6,12,12-tetrakis(4-hexylphenyl)-s-indacenodithieno[3,2-b]thiophene]methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)]]bis(propanedinitrile) (ITIC) to fabricate the corresponding photovoltaic devices. The two-dimensional conjugated polymer PBDTT-TPD shows enhanced extinction coefficient, deeper HOMO energy level and better hole transport performance, resulting in improved PCE of 6.17%. To further boost the performances of the polymers, a small molecular acceptor 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl) bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) with down-shifted energy level was also used to blend with the two polymers in PSCs. Despite the open-circuit voltage (VOC) of the PBDTT-TPD:IDIC-based device is slightly decreased, the short-circuit current density (JSC) and fill factor (FF) are simultaneously improved, yielding an promising PCE of 7.15%. These results indicate that two-dimensional conjugated TPD-based polymers can be potential application as medium bandgap polymeric donor to match with small molecular acceptors having suitable molecular energy levels to get high efficiency in PSCs.
关键词： Non-fullerene acceptors,Thieno[3,4-c]pyrrole-4,6-dione,Energy level offsets,Polymer solar cells,Thermal annealing
更新于2025-09-11 14:15:04
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Intrinsic Photo-degradation and Mechanism of Polymer Solar Cells: The crucial role of Non-fullerene Acceptor
摘要： The performances of polymer solar cells (PSCs) based on non-fullerene acceptors (NFAs) have improved remarkably in recent years, but such devices are insufficiently stable for practical applications. Here, we investigated the effects of NFAs on PSC long-term stability. We found that high performance PBDB-T:ITIC solar cells exhibit much lower stability than PTB7:PC71BM devices in the 1 sun light-soaking test; when compared with their initial performances, the performance of PTB7:PCBM-based solar cells remains above 60% for over 4000 h, whereas that of PBDB-T:ITIC-based devices is reduced to one fifth after 1000 h. We demonstrated that the ITIC-based PSCs exhibit poor photo-stability because ITIC at the interface of the ZnO/active film is readily decomposed by a photocatalytic reaction; this poor stability arises because the vinyl group of ITIC is chemically more vulnerable than the stable aromatic units in the organic active materials. The decomposition of ITIC results in the degradation of the electron transport properties of the active materials located close to ZnO, which leads to severe burn-in degradation and reduced FF and VOC under illumination. It is thus highly important to develop intrinsically stable organic materials composed of chemically stable building blocks in order to realize stable and high efficiency PSCs.
关键词： polymer solar cells,photocatalytic reaction,non-fullerene acceptors,photo-stability,ITIC
更新于2025-09-11 14:15:04
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Building Blocks for High‐Efficiency Organic Photovoltaics: Interplay of Molecular, Crystal, and Electronic Properties in Post‐Fullerene ITIC Ensembles
摘要： Accurate single-crystal X-ray diffraction data offer a unique opportunity to compare and contrast the atomistic details of bulk heterojunction photovoltaic small-molecule acceptor structure and packing, as well as provide an essential starting point for computational electronic structure and charge transport analysis. Herein, we report diffraction-derived crystal structures and computational analyses on the n-type semiconductors which enable some of the highest efficiency organic solar cells produced to date, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (ITIC) and seven derivatives (including three new crystal structures: 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-propylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (ITIC-C3), 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(3-hexylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (m-ITIC-C6), and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-butylphenyl)-dithieno[2,3-d:2’,3’-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (ITIC-C4-4F). IDTT acceptors typically pack in a face-to-face fashion with π–π distances ranging from 3.28–3.95 ?. Additionally, edge-to-face packing is observed with S?π interactions as short as 3.21–3.24 ?. Moreover, ITIC end group identities and side chain substituents influence the nature and strength of noncovalent interactions (e.g. H-bonding, π–π) and thus correlate with the observed packing motif, electronic structure, and charge transport properties of the crystals. Density functional theory (DFT) calculations reveal relatively large nearest-neighbor intermolecular π-π electronic couplings (5.85–56.8 meV) and correlate the nature of the band structure with the dispersion interactions in the single crystals and core–end group polarization effects. Overall, this combined experimental and theoretical work reveals key insights into crystal engineering strategies for indacenodithienothiophene (IDTT) acceptors, as well as general design rules for high-efficiency post-fullerene small molecule acceptors.
关键词： density functional calculations,crystal structure,non-fullerene,molecular modelling,solar cells
更新于2025-09-11 14:15:04
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Acceptor Gradient Polymer Donors for Non-Fullerene Organic Solar Cells
摘要： In organic solar cells, maximizing the open-circuit voltage (VOC) via minimization of the ionization energy or electron a?nity o?sets of the blended donor and acceptor often comes at the expense of achieving a considerable amount of short-circuit current (JSC). To explore a hypothesis for the design of materials that may circumvent this tradeo?, eight structurally similar polymers were synthesized consisting of a ?uorinated/non-?uorinated benzothiadiazole (BTDF/BTD) strong acceptor moiety, a thiophene ester (TE) weak acceptor, and various donor units composed of bithiophene (T2), biEDOT, and benzodithiophene (BDT) to form six acceptor gradient and two nongradient polymers. The acceptor gradient motif was designed and theorized to induce more facile exciton dissociation in low driving force solar cells by creating a further separated intramolecular charge-transfer state between the strong BTD acceptor and various donor units through a bridging TE component. Solar cells were fabricated using the eight polymers blended with phenyl-C71-butyric-acid methyl ester (PC71BM) to reveal two top performing isomeric polymers, T2-BTDF-(TE2) and TE2-BTDF-(T2), which were further tested with several non-fullerene acceptors (NFAs): EH-IDTBR, ITIC, and ITIC-4F. In order to fabricate optimally performing solar cells, a 0.2 eV ionization energy o?set was found to be essential or the short-circuit current of the NFA cells diminished dramatically. Ultimately, optimized NFA solar cells were fabricated using ITIC-4F paired with each of the top performing polymers to produce an average PCE of 7.3% for TE2-BTDF-(T2) (nongradient) and 3.6% for T2-BTDF-(TE2) (gradient). The acceptor gradient e?ect was not shown to reduce the amount of charge recombination in NFA solar cells mainly due to the inability to fabricate solar cells, with minimal ionization energy or electron a?nity o?sets along with morphological complications. This work stresses the importance of acquiring accurate ionization energies and electron a?nities when characterizing solar cell energetics, as di?erences as small as 0.1 eV in the o?sets can make a signi?cant impact on overall charge collection.
关键词： acceptor gradient polymers,open-circuit voltage,electron affinity offset,charge recombination,organic solar cells,non-fullerene acceptors,ionization energy offset,short-circuit current
更新于2025-09-11 14:15:04
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Optimizing Microstructure Morphology and Reducing Electronic Losses in 1-cm <sup>2</sup> Polymer Solar Cells to Achieve Efficiency over 15%
摘要： The successful demonstration of high-performance organic solar cells (OSCs) on relatively large-area is vital for their industrial viability and future application. When the device area is enlarged from several mm2 to the scale of >1 cm2, critical losses caused by film inhomogeneity or defects in the photoactive layer strongly restrict the performance and reproducibility of OSCs. In this work, we demonstrate that through delicate optimization of photoactive layer and minimization of optoelectronic losses, an impressive external quantum efficiency maximum up to 88% and an internal quantum efficiency peak of 97% are achieved for non-fullerene OSCs. Further incorporating fullerene as the third component into the photoactive layer optimizes the microstructure morphology, enabling the large-scale devices with an area of >1.1 cm2 surpassing the 15% efficiency milestone. The exciting results demonstrated in this work highlight the strategic priority to minimize losses through both materials and electronic engineering towards high-performance large-area OSCs.
关键词： large-area devices,photoactive layer,non-fullerene acceptors,organic solar cells,electronic losses,microstructure morphology
更新于2025-09-11 14:15:04
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Propeller-like acceptors with difluoride perylene diimides for organic solar cells
摘要： Perylene diimide (PDI) is one of most intensively studied non-fullerene small molecule acceptors (SMAs). By fluorination on the conjugated backbone, a new PDI with difluoride substitution on adjacent bay positions of PDI is prepared. Then, four propeller-like SMAs are obtained by linking four PDIs with an aromatic core, wherein the molecular geometry is modulated by ring fusion of the aromatic core. Further study reveals that fluorination is helpful to enhance the absorption intensity, and thus promote the current density in organic solar cells. In addition, the ring-fused strategy is able to suppress the distortion and rotation of relevant molecules. Therefore, these four acceptors exhibit significantly diversity of photovoltaic performance, wherein the acceptor FPDIF4-DTC consisting of a fused core and fluoro-substituted PDIs shows a best efficiency of 5.1%. This result implies that fluorination on PDI conjugated backbone is a successful way to construct promising SMAs.
关键词： Perylene Diimide,Fluorination,Non-fullerene acceptor,Organic solar cells
更新于2025-09-11 14:15:04