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Perylene diimide based star-shaped small molecular acceptors for high efficiency organic solar cells
摘要： We designed and synthesized three PDI derivatives (PDI-II, PDI-III and PDI-IV). All these acceptor molecules have a central benzene core and the PDI units are linked to the central benzene core by an acetylene spacer. PDI-II is a linear molecule, which bears two flanked PDI units, PDI-III is a c3-symmetrical star-shaped molecule with three peripheral PDI units, and PDI-IV is a star-shaped molecule with four PDI units linked to the 1,2,4,5-positions of the central benzene core. These absorption features indicated that the PDI units in PDI-II and PDI-III are planar, whereas the PDI units in PDI-IV are twisted due to the steric crowding. Compared with the linear PDI-II, the star-shape could e?ectively prevent PDI-III and PDI-IV from forming large aggregates when blended with the donor polymer PBDB-T. PBDB-T:PDI-II, PBDB-T:PDI-III and PBDB-T:PDI-IV based OSCs gave power conversion e?ciencies (PCEs) of 3.05%, 6.00% and 1.04%, respectively. The big di?erences in electron mobility and PCE for PDI-III and PDI-IV are probably due to the fact that the PDI units in PDI-III are planar and those in PDI-IV are twisted.
关键词： Perylene diimide,power conversion efficiencies,star-shaped small molecular acceptors,organic solar cells
更新于2025-09-11 14:15:04
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Effects of Monofluorinated Positions at the End-Capping Groups on the Performances of Twisted Non-Fullerene Acceptor-Based Polymer Solar Cells
摘要： Recently, the main-chain twisted small molecules are attractive as electron-acceptors in polymer solar cells (PSCs) for their up-shifted molecular energy levels, enhanced extinction coefficients, better charge extraction properties along with longer carrier lifetime and lower recombination rate relative to their planar analogues, which are conducive to the power conversion efficiency (PCE) promotion of PSCs. To further probe the ‘structure-performance’ correlation of main-chain twisted acceptors, in particular the mono-fluorine substituted sites on the performances of the resultant acceptors, two new main-chain twisted small molecules were synthesized, in which a fluorine atom was introduced at different sites on the end-capping group 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (INCN). Although finely structural modification was adopted, quite different performances were obtained in the two acceptors. Compared to the 3-fluorinated analogue (i-IEICO-F3), the mixture of 4-florinated and 5-fluorinated isomers (i-IEICO-2F) exhibited higher dipole moment, enlarged molar extinction coefficient with bathochromic-shifted absorption region, suppressed charge recombinations with balanced charge mobilities, and slightly enhanced crystallinity. In combination with a fluorobenzotriazole-based medium-bandgap polymer (J52), a high efficiency of 12.86% was resultantly achieved in i-IEICO-2F-based device, which is superior to the result (7.65%) of i-IEICO-F3 device, revealing the importance of mono-fluorinated positions on the performances of main-chain twisted non-fullerene acceptors.
关键词： Power conversion efficiency,Fluorinated position effects,Main-chain twisted small molecular acceptors,Polymer solar cells,Non-fullerene acceptors
更新于2025-09-11 14:15:04
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Efficient hybrid colloidal quantum dot/organic solar cells mediated by near-infrared sensitizing small molecules
摘要： Solution-processed semiconductors are promising materials to realize optoelectronic devices that combine high performance with inexpensive manufacturing. In particular, the exploitation of colloidal quantum dots (CQDs) capable of harvesting infrared photons, in conjunction with visible-absorbing organic chromophores, has been demonstrated as an interesting route. Unfortunately, CQD/organic hybrid photovoltaics have been limited to power conversion efficiencies (PCEs) below 10% due to chemical mismatch and difficulties in facilitating charge collection. Here we devise a hybrid architecture that overcomes these limitations by introducing small molecules into the CQD/organic stacked structure. The small molecule complements CQD absorption and creates an exciton cascade with the host polymer, thus enabling efficient energy transfer and also promoting exciton dissociation at heterointerfaces. The resulting hybrid solar cells exhibit PCEs of 13.1% and retain over 80% of their initial PCE after 150?h of continuous operation unencapsulated, outperforming present air-processed solution-cast CQD/organic photovoltaics.
关键词： hybrid photovoltaics,organic solar cells,small molecules,power conversion efficiency,colloidal quantum dots
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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Optimized mixed phases to achieve improved performance of organic solar cells
摘要： In the three-phase (pure donor, pure acceptor, and mixed phases) morphologies of organic solar cells, the mixed phases produce an energy cascade that promotes the generation of free carriers. However, how to optimize the content of the mixed phases is a challenging problem. The authors proposed to control different content of mixed phases in DRTB-T and IDIC blends by additive and solvent vapor annealing (SVA). The authors ?rst formed the largest extent amount of mixed phases by the additive cinene (2%) to inhibit the crystallization of DRTB-T and IDIC. And then, different amounts of mixed phases were achieved by further SVA for different times (from 0 to 50 s) to increase the content of pure DRTB-T and IDIC phases. The energetic offsets (ΔE) of pure and mixed phases gradually decrease from 0.529 to 0.477 eV for different content of mixed phases. When ΔE was 0.498 eV, the highest photocurrent density (Jsc) was obtained. The power conversion ef?ciency was increased from 3.23% (without any treatment) to 8.54%. Therefore, the authors demonstrated that the optimized content of the mixed phases is critical to device performance.
关键词： solvent vapor annealing,additive,organic solar cells,power conversion efficiency,DRTB-T,energy cascade,cinene,IDIC,mixed phases
更新于2025-09-11 14:15:04
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Effect of electron donor and acceptor in dithienopyrrolobenzothiadiazole-based organic dyes for efficient quasi-solid-state dye-sensitized solar cells
摘要： Three new organic dyes H1-3 with dithienopyrrolobenzothiadiazole moiety as the π-bridge have been synthesized and applied in quasi-solid-state dye-sensitized solar cells. The influences of different electron acceptor of the sensitizers on the photo-physical, electrochemical and photovoltaic performances have been studied. The results show that the inserted electron-withdrawing unit benzothiadiazole in the acceptor part can obviously enhance the light-harvesting ability of the dyes. In addition, the introduced benzothiadiazole moiety in acceptor can increase the π-electron distribution in LUMO level, which may facilitate to the photogenergated electrons injection into TiO2 film. The effects of different electron donor on the solar cell performances have been evaluated. The dihexyloxy substituted triphenylamine is better to suppress the intermolecular aggregation and restrain electron recombination. Finally, the quasi-solid-state solar cell sensitized by dye H2 with 1 mM chenodeoxycholic acid as the co-adsorbent obtains a power conversion efficiency of 7.56%, which close to the level of dye N719 (7.66%) under the same condition.
关键词： Benzothiadiazole,Electron donor,Quasi-solid-state dye-sensitized solar cells,Power conversion efficiency,Dithienopyrrolobenzothiadiazole
更新于2025-09-11 14:15:04
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Lateral InSe p–n Junction Formed by Partial Doping for Use in Ultrathin Flexible Solar Cells
摘要： Two-dimensional InSe possesses good electrical conductivity, intrinsic and structural flexibility, high chemical stability, and a tunable band gap, enabling it to be a promising candidate for flexible and wearable solar cells. Here we construct a lateral p?n junction by partially doping molybdenum trioxide (MoO3) at the surface of the InSe monolayer. Our density functional theory calculations reveal that the strong hybridization between MoO3 and InSe induces a lateral built-in electric field in the partially doped substrate and promotes the effective separation of carriers. Under a large range of external stains, the doped InSe can maintain the direct band gap, and the lateral structure device exhibits power conversion efficiencies over 5% and high carrier mobility around 1000 cm2 V?1 s?1. In particular, a power conversion efficiency of 20.7% can be achieved with 10% compressive strain. The partially doped InSe monolayer is expected to be used as an ultrathin flexible solar cell.
关键词： lateral p?n junction,density functional theory,carrier mobility,flexible solar cells,power conversion efficiency,Two-dimensional InSe,molybdenum trioxide
更新于2025-09-11 14:15:04
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High-Performance Ternary Organic Solar Cells Enabled by Combining Fullerene and Nonfullerene Electron Acceptors
摘要： Recently, by elaborately designing nonfullerene acceptors and selecting suitable polymer donors great progresses have been made towards binary organic solar cells (OSCs) with power conversion efficiencies (PCEs) over 15%. Ternary organic photovoltaics by introducing a third component into the host binary system is recognized to be highly effective to elevate the performance through extending the light absorption, manipulating the recombination behavior of the carriers, and improving the morphology of the active layer. In this work, we synthesized a new electron-acceptor ZITI-4F matching it with the wide-bandgap polymer donor PBDB-T The PBDB-T:ZITI-4F-based OSC showed a high PCE of 12.33%. After introducing 40% of PC71BM as the third component, the ternary device achieved an improved PCE of 13.40% with simultaneously improved photovoltaic parameters. The higher performance of the ternary device can be attributed to the improved and more balanced charge mobility, reduced bimolecular recombination, and more favorable morphology. These results indicate that the cooperation of a fullerene-based acceptor and a nonfullerene acceptor to fabricate ternary OSCs is an effective approach to optimizing morphology and therefore to increase the performance of OSCs.
关键词： ternary organic solar cells,power conversion efficiencies,indenoin-dene,electron acceptors
更新于2025-09-11 14:15:04
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Characteristics of Diamond-Like Carbon Films Fabricated by Using a Filtered Vacuum Arc System for Dye-Sensitized Solar Cells
摘要： Dye-sensitized solar cells (DSSC) based on diamond-like carbon (DLC) anti-re?ection coating (ARC) thin ?lms are investigated. The DLC ?lm was proposed to improve the cell performance of DSSC devices. In this work, the DLC ?lms were fabricated by using the FVA (?ltered vacuum arc) method, the structural, optical, and physical properties of the fabricated DLC ?lms with various ?lm thicknesses were experimentally investigated. All DLC ?lms showed smoother and more uniform surfaces with increasing ?lm thickness. Furthermore, the values of rms surface roughness, friction coe?cient, the refractive index, and the absorption coe?cient increased with increasing ?lm thickness, the hardness and the elastic modulus of the DLC ?lms were improved. These results are associated with the increased sp3 contents in the amorphous carbon ?lm due to the e?ects of the energetic ion bombardment during ?lm deposition.
关键词： DLC,Filtered vacuum arc (FVA),Hardness,Anti-re?ection,Friction coe?cient,Power conversion e?ciency
更新于2025-09-11 14:15:04
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Effect of Plasmonic Ag Nanoparticles on the Performance of Inverted Perovskite Solar Cells
摘要： Recently, perovskite solar cells (PSCs) attracted phenomenal research interest owing to their potential as the next-generation photovoltaics. Despite rapid development in this field, increasing their power conversion efficiency (PCE) remains a critical issue for the commercialization of PSCs. In this work, we have investigated the application of Ag nanoparticle (NPs) layers via vapour-phase deposition onto perovskite active layers. The formation of unique, crescents shaped Ag NPs is confirmed by scanning electron microscopy (SEM), which shows that the NPs self-assemble along the grain boundaries of perovskite leading to their unique shape. The PCE for devices incorporating an optimized size of Ag NPs of 79 ± 6 nm increased from 11.63% to 13.46% with the improvement factor of 15.74%. The increase in PCE mainly attributed to the increase in short circuit current (Jsc) that is assigned to an increase in optical path length and absorption. As NPs possess the ability to increase the optical path length of photons in the device due to the near field and far-field enhancement (plasmonic scattering) and consequently may act to improve the photon to electron conversion efficiency (ΔIPCE) and PCE of PSCs. Moreover, ultraviolet photoelectron spectroscopy revealed a decrease in hole injection barrier (?h) also contributed to enhanced performance.
关键词： Power conversion efficiency,Ag crescents,Perovskite solar cells,Ag nanoparticles
更新于2025-09-11 14:15:04