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High-Performance Organic Photodetectors by Introducing a Non-Fullerene Acceptor to Broaden Long Wavelength Detective Spectrum
摘要： We demonstrate the broadband visible organic photodetectors (OPDs) by introducing a non-fullerene acceptor of 3,9-bis(2-methylene-(3-(1,1dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3d:2,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITIC) into the bulk heterojunction (BHJ) based on a conventional system of poly(3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl C71-butyric acid methyl ester (PC71BM) .The resultant OPDs exhibit a specific detectivity beyond 1012 Jones in the whole visible region ranged from 380 nm to 760 nm, and the highest detectivity reaches 2.67 × 1012 Jones at 710 nm. UV-Vis absorption spectrum, steady-state photoluminescence, atomic force microscopy, and space-charge-limited current property were applied to analyze the film characteristics of obtained OPDs. Owing to the long-wavelength absorption band of ITIC, the spectral photodetection range has been broadened effectively, and better film morphology, more effective energy transfer, and the reduced electron mobility in the active layer are responsible for the excellent photodetection capability. The proposed scheme provides a reliable strategy for implementing high-performance broadband visible OPDs.
关键词： Organic photodetectors,UV-Vis absorption,Non-fullerene acceptor,Surface morphology,Full visible light photodetection
更新于2025-09-11 14:15:04
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17% efficiency organic photovoltaic cell with superior processability
摘要： The development of organic photoactive materials, especially the new-emerging non-fullerene electron acceptors (NFAs), has enabled rapid progress in organic photovoltaic (OPV) cells in recent years. Although the power conversion efficiencies (PCEs) of the top-performance OPV cells have surpassed 16%, the devices are usually fabricated via a spin-coating method and are not suitable for large-area production. Here, we demonstrate that the fine-modification of the flexible side chains of NFAs can yield 17% PCE for OPV cells. More crucially, as the optimal NFA has a suitable solubility and thus a desirable morphology, the high efficiencies of spin-coated devices can be maintained when using the scalable blade-coating processing technology. Our results suggest that the optimization of the chemical structures of the OPV materials can improve the device performance. This has great significance in larger-area production technologies that provide important scientific insights for the commercialization of OPV cells.
关键词： non-fullerene acceptor,processability,power conversion efficiency,organic photovoltaic cells,scalable large-area production
更新于2025-09-11 14:15:04
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Insights into Fullerene Passivation of SnO <sub/>2</sub> Electron Transport Layers in Perovskite Solar Cells
摘要： Interfaces between the photoactive and charge transport layers are crucial for the performance of perovskite solar cells. Surface passivation of SnO2 as electron transport layer (ETL) by fullerene derivatives is known to improve the performance of n–i–p devices, yet organic passivation layers are susceptible to removal during perovskite deposition. Understanding the nature of the passivation is important for further optimization of SnO2 ETLs. X-ray photoelectron spectroscopy depth profiling is a convenient tool to monitor the fullerene concentration in passivation layers at a SnO2 interface. Through a comparative study using [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and [6,6]-phenyl-C61-butyric acid (PCBA) passivation layers, a direct correlation is established between the formation of interfacial chemical bonds and the retention of passivating fullerene molecules at the SnO2 interface that effectively reduces the number of defects and enhances electron mobility. Devices with only a PCBA-monolayer-passivated SnO2 ETL exhibit significantly improved performance and reproducibility, achieving an efficiency of 18.8%. Investigating thick and solvent-resistant C60 and PCBM-dimer layers demonstrates that the charge transport in the ETL is only improved by chemisorption of the fullerene at the SnO2 surface.
关键词： solar cell,fullerene,metal halide perovskite,tin oxide,passivation
更新于2025-09-11 14:15:04
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Effect of Electron-Acceptor Content on the Efficiency of Regioregular Double-Cable Thiophene Copolymers in Single-Material Organic Solar Cells
摘要： Three regioregular thiophenic copolymers, characterized by a bromine atom or a C60-fullerene group at different molar ratios at the end of a decamethylenic plastifying side chain, have been successfully synthesized using a straightforward postpolymerization functionalization procedure based on a Grignard coupling reaction. Owing to their good solubility in common organic solvents, the products were fully characterized using chromatographic, spectroscopic, thermal, and morphological techniques and used as single materials in the photoactive layers of organic solar cells. The photoconversion efficiencies obtained with copolymers were compared with those of a reference cell prepared using a physical blend of the precursor homopolymer and [6,6]-phenyl-C61-butyric acid methyl ester. The best results were obtained with COP2, the copolymer with a 21% molar content of C60-functionalized side chains. The use of the double-cable polymer made possible an enhanced control on the nanomorphology of the active blend, thus reducing phase-segregation phenomena as well as the macroscale separation between the electron-acceptor and -donor components, yielding a power conversion efficiency higher than that of the reference cell (4.05 vs 3.68%). Moreover, the presence of the halogen group was exploited for the photo-cross-linking of the active layer immediately after the thermal annealing procedure. The cross-linked samples showed an increased stability over time, leading to good efficiencies even after 120 h of accelerated aging: this was a key feature for the widespread practical applicability of the prepared devices.
关键词： photo-cross-linking,C60-fullerene,double-cable polymer,thermal annealing,regioregular thiophenic copolymers,Grignard coupling reaction,organic solar cells,photoconversion efficiencies
更新于2025-09-11 14:15:04
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Modulation of Three p-Type Polymers Containing a Fluorinated-Thiophene-Fused-Benzotriazole Unit To Pair with a Benzotriazole-Based Non-fullerene Acceptor for High <i>V</i> <sub/>OC</sub> Organic Solar Cells
摘要： Three 6-?uoro-thieno[2′,3′:4,5]benzo[1,2-d][1,2,3]triazole (fBTAZT) containing copolymers, named as PfBTAZT-H, PfBTAZT-F, and PfBTAZT-Cl, were employed to pair with a benzo[1,2-d][1,2,3]triazole (BTA) based non-fullerene acceptor BTA3 for the applicaition in organic solar cells (OSCs). By introducing ?uorine or chlorine atoms into the thiophene side chains on BDT units, the highest occupied molecular orbital (HOMO) energy levels of polymers shift down in sequence, and PfBTAZT-Cl shows an obvious blue-shift of absorption spectrum. PfBTAZT-F:BTA3-based OSC attains a VOC of 1.05 V, a JSC of 11.83 mA cm?2, and FF of 0.62, leading to a PCE of 7.69%, which are higher than that of PfBTAZT-H:BTA3 (VOC = 0.99 V, JSC = 11.60 mA cm?2, FF = 0.58, and PCE = 6.65%) due to its well-matched HOMO energy level, higher charge mobilities, and favorable ?lm morphology. More surprisingly, chlorinated polymer PfBTAZT-Cl obtains the highest VOC of 1.20 V and PCE of 8.00%, which is attributed to the lowest HOMO energy level, largely decreased voltage loss (ΔVloss = 0.56 V compared to 0.77 V for PfBTAZT-H:BTA3 0.71 V for PfBTAZT-F:BTA3), more complementary absorption with that of BTA3, and e?ective charge generation. Our results demonstrate that chlorination is an e?ective approach to realize a high PCE and VOC and thiophene-fused benzotriazole (BTAZT) based polymers are also good candidates for material combinations in “Same-A-Strategy” (SAS).
关键词： fluorinated-thiophene-fused-benzotriazole,PCE,non-fullerene acceptor,organic solar cells,high VOC,benzotriazole-based
更新于2025-09-11 14:15:04
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Kinetic Monte Carlo Study of the Role of the Energetic Disorder on the Open-circuit Voltage in Polymer:Fullerene Solar Cells
摘要： One major factors limiting the e?ciency in organic solar cells (OSCs) is the low open-circuit voltage (Voc). Existing theoretical studies link the Voc with the charge transfer (CT) state and non-radiative recombination. However, also morphology and energetic disorder can have a strong impact on the Voc within realistic bulk-heterojunction OSCs. In this work, we present a kinetic Monte Carlo study on the role of the energetic disorder on the maximum Voc. We compute the quasi-Fermi level splitting for di?erent energetic disorder and analyze the impact of the energetic disorder at the donor-acceptor interface as well as correlations in the site energies on the Voc. Our results show that the interface strongly controls the maximum Voc. For a higher interface disorder, charge densities and non-geminate recombination increases, and the Voc is reduced. Furthermore, the correlated morphologies show an increase in the maximum Voc and a reduced impact of the energetic disorder.
关键词： Open-circuit Voltage,Kinetic Monte Carlo,Energy Conversion and Storage,Plasmonics and Optoelectronics,Polymer:Fullerene Solar Cells
更新于2025-09-11 14:15:04
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Peculiar Photoinduced Electron Transfer in Porphyrin-Fullerene Akamptisomers
摘要： Porphyrin-fullerene dyads are promising candidates for organic photovoltaic devices. Electron transfer (ET) properties of the molecular devices depend significantly on the mutual position of the donor and acceptor. Recently, a new type of molecular isomerism (akamptisomerism) has been discovered. In the present study, we explore how photoinduced ET can be modulated by passing from one akamptisomer to another. To this aim, four akamptisomers of quinoxalinoporphyrin–[60]fullerene complex are selected for the computational study. The most striking finding is that, depending on the isomer, the porphyrin unit in the dyad can act as either electron donor or electron acceptor. Thus, the stereoisomeric diversity allows one to change the direction of ET between the porphyrin and fullerene moieties. To understand the effect of akamptisomerism on the photoinduced ET processes a detailed analysis of initial and final states involved in the ET is performed. The computed rate for charge separation is estimated to be in the region of 1-10 ns-1. The formation of a long-living quinoxalinoporphyrin anion-radical species is predicted.
关键词： quinoxalinoporphyrin–[60]fullerene complex,Porphyrin-fullerene dyads,photoinduced electron transfer,organic photovoltaic devices,akamptisomerism
更新于2025-09-10 09:29:36
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The model of the fullerene C60 and its ions C60+, C60??pseudopotentials for molecular dynamics purposes
摘要： The model pseudopotentials of C?60, C60 and C+60 have been constructed on the base of the total electrostatic potentials obtained as a result of ab initio-based calculations. The radial distance dependence of the pseudopotential is obtained by averaging with respect to the spherical angles of the total electrostatic potential. The role of the electronic correlations is investigated by comparison results of using of the di?erent exchange-correlation functional within the density functional theory. All pseudopotentials are ?tted by the ?ne approximation functions and can be applied for molecular dynamics tasks.
关键词： molecular dynamics,electronic correlations,pseudopotentials,fullerene C60,ab initio calculations
更新于2025-09-10 09:29:36
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Non-Fullerene Small Molecule Acceptors Containing Barbituric Acid End Groups for Use in High-performance OPVs
摘要： We synthesized two new bithiophene-based small molecules, TT-BBAR, and TT-OBAR, having butyl- and octyl-substituted barbituric acid (BAR) groups, respectively, via a well-known synthetic method, the Knoevenagel condensation, in high yield. These small molecules displayed solubilities and thermal stabilities sufficient for the fabricating organic photovoltaic cells (OPVs) and were designed to have relatively low molecular orbital energy levels and act as non-fullerene acceptors (NFAs) for use in OPVs upon introduction of electron-withdrawing BAR groups at both ends. For example, the LUMO and HOMO energy levels of TT-OBAR were ?3.79 and of ?5.84 eV, respectively, clearly lower than those of a polymer donor, PTB7-Th. Importantly, the small molecules featured an energy offset with PTB7-Th sufficient for achieving exciton dissociation. The optical and electrochemical properties of TT-BBAR and TT-OBAR did not depend on the alkyl chain length. Finally, OPV devices were fabricated in an inverted structure using a solvent process. The power conversion efficiency of TT-OBAR (1.34%) was found to be slightly higher than that of TT-BBAR (1.16%). The better performance and higher short-circuit current value of TT-OBAR could be explained based on a morphological AFM study, in which TT-OBAR displayed a more homogeneous morphology with a root-mean-square value of 1.18 nm compared to the morphology of TT-BBAR (11.7 nm) induced by increased alkyl chain length.
关键词： Barbituric acid,Organic photovoltaics,Organic photovoltaic cell,Non-fullerene acceptor
更新于2025-09-10 09:29:36
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Introducing Four 1,1-Dicyanomethylene-3-Indanone (IC) End-capped Groups as an Alternative Strategy for the Design of Small Molecular Nonfullerene Acceptors
摘要： Linear A-D-A or A-π-D-π-A architectures are predominant in the design of promising non-fullerene acceptors (NFAs), which promoted the rapid progress of organic solar cells (OSCs). However, utilization of four electron-accepting units (A) to construct four-armed NFAs is rarely reported and the relationship of structure-properties-performance is unclear. In this study, we designed and synthesized a novel acceptor (A401) with (AA)-π-D-π-(AA) configuration, where four 1,1-dicyanomethylene-3-indanone (IC) groups were used as the end-capped segments. When A401 was paired with a classic p-type polymer PBDB-T, a power conversion efficiency (PCE) of 7.54% could be achieved, which was much higher than that of the reported two-armed analogue of DC-IDT2T (3.93%). The improved photovoltaic performance of A401 should be ascribed to the high electron-affinity. Our results indicate introducing more end-capped electron-accepting units is a simple and effective alternative strategy for the design of promising NFAs. Our conceptualized molecular architecture will encourage further research of high-performance multi-armed NFAs.
关键词： photovoltaic performance,electron-affinity,electron-accepting units,organic solar cells,non-fullerene acceptors
更新于2025-09-10 09:29:36