Asymmetric Glycolated Substitution for Enhanced Permittivity and Ecocompatibility of High-Performance Photovoltaic Electron Acceptor
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ABSTRACT:
SUBMITTER: Li T
PROVIDER: S-EPMC8549046 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Molecular engineering plays a critical role in the development of electron donor and acceptor materials for improving power conversion efficiency (PCE) of organic photovoltaics (OPVs). The halogenated acceptor materials in OPVs have shown high PCE. Here, to investigate the halogenation mechanism and the effects on OPV performances, based on the density functional theory calculations with the optimally tuned screened range-separated hybrid functional and the consideration of solid polarization effects, we addressed the halogenation effects of acceptor ITIC, which were modeled by bis-substituted ITIC with halogen and coded as IT-2X (X = F, Cl, Br), and PBDB-T:ITIC, PBDB-T:IT-2X (X = F, Cl, Br) complexes on their geometries, electronic structures, excitations, electrostatic potentials, and the rate constants of charge transfer, exciton dissociation (ED), and charge recombination processes at the heterojunction interface. The results indicated that halogenation of ITIC slightly affects molecular geometric structures, energy levels, optical absorption spectra, exciton binding energies, and excitation properties. However, the halogenation of ITIC significantly enlarges the electrostatic potential difference between the electron acceptor and donor PBDB-T with the order from fluorination and chlorination to bromination. The halogenation also increases the transferred charges of CT states for the complexes. Meanwhile, the halogenation effects on CT energies and electron process rates depend on different haloid elements. No matter which kinds of haloid elements were introduced in the halogenation of acceptors, the ED is always efficient in these OPV devices. This work provides an understanding of the halogenation mechanism, and is also conducive to the designing of novel materials with the aid of the halogenation strategy.
| S-EPMC8708652 | biostudies-literature
Project description:Three alternated D-π-A type 5,10-bis(triisopropylsilylethynyl)dithieno[2,3-d:2',3'-d']-benzo[1,2-b:4,5-b']dithiophene (DTBDT-TIPS)-based semiconducting conjugated copolymers (CPs), PDTBDT-TIPS-DTBT-OD, PDTBDT-TIPS-DTFBT-OD, and PDTBDT-TIPS-DTNT-OD, bearing different A units, including benzothiadiazole (BT), 5,6-difluorinated-BT (FBT) and naphtho[1,2-c:5,6-c']-bis[1,2,5]thiadiazole (NT), were designed and synthesized to investigate the impact of the variation in electron-deficient units on the properties of these photovoltaic polymers. It was exhibited that the down-shifted highest occupied molecular orbital energy level (EHOMO), the enhanced aggregation in both the chlorobenzene solution and the solid film, as well as the better molecular planarity, were achieved using methods involving fluorination and the replacement of BT with NT on the polymer backbone. The absorption profile was little changed upon fluorination; however, it was greatly broadened during replacement of BT with NT. Consequently, the optimized photovoltaic device based on the PDTBDT-TIPS-DTNT-OD exhibited synchronous enhancements in the open-circuit voltage (VOC) of 0.88 V, the short-circuit current density (JSC) of 7.21 mA cm-2, and the fill factor (FF) of 52.99%, resulting in a drastic elevation in the PCE by 129% to 3.37% compared to that of the PDTBDT-TIPS-DTBT-OD. This was triggered by PDTBDT-TIPS-DTNT-OD's broadened absorption, deepened EHOMO, improved coplanarity, and enhanced SCLC mobility (which increased 3.9 times), as well as a favorable morphology of the active layer. Unfortunately, the corresponding PCE deteriorated after incorporating fluorine into the BT, due to the oversized aggregation and large phase separation morphology in the blend films, severely impairing its JSC. Our preliminary results demonstrated that the replacement of BT with NT in a D-π-A type polymer backbone was an effective strategy of tuning the molecular structure to achieve highly efficient polymer solar cells (PSCs).
| S-EPMC6401703 | biostudies-literature
Project description:Herein, we report the synthesis of nontoxic pyrite iron sulfide (FeS2) nanocrystals (NCs) using a two-pot method. Moreover, we study the influence of these NCs incorporated into the PTB7:PC71BM active layer of bulk-heterojunction ternary organic photovoltaic (OPV) cells. The OPV devices are fabricated with the direct configuration glass/ITO/PEDOT:PSS/PTB7:PC71BM:FeS2/PFN/FM. The Field's metal (FM) is a eutectic alloy composed of 32.5% Bi, 51% In and 16.5% Sn by weight that melts at 62 °C. It is deposited on the active layer/PFN under atmospheric conditions. Ternary active layers are prepared by adding small amounts of the semiconducting FeS2 NCs at different weight ratios of 0.0, 0.25, 0.5, and 1.0 wt % with respect to the electron donor PTB7. With respect to the reference device (without FeS2), a 21% increase in the power conversion efficiency (PCE) is observed for OPVs with 0.5 wt % FeS2, such that the PCE of the OPVs is enhanced from 5.69 to 6.47%. According to the Kruskal-Wallis and Mann-Whitney statistical tests, all OPV devices follow the same trend.
| S-EPMC6880843 | biostudies-literature
Project description:The ternary strategy has been recognized as an effective method to improve the photovoltaic performance of organic solar cells (OSCs). In ternary OSCs, the complementary or broadened absorption spectrum, optimized morphology, and enhanced photovoltaic performance could be obtained by selecting a third rational component for the host system. In this work, a fused ring electron acceptor named BTMe-C8-2F, which possesses a high-lying lowest unoccupied molecular orbital (LUMO) energy level and a complementary absorption spectrum to PM6:Y6, was introduced to a PM6:Y6 binary system. The ternary blend film PM6:Y6:BTMe-C8-2F showed high and more balanced charge mobilities, and low charge recombination. Therefore, the OSC based on the PM6:Y6:BTMe-C8-2F (1 : 1.2 : 0.3, w/w/w) blend film achieved the highest power conversion efficiency (PCE) of 17.68%, with an open-circuit voltage (VOC) of 0.87 V, a short-circuit current (JSC) of 27.32 mA cm-2, and a fill factor (FF) of 74.05%, which are much higher than the binary devices of PM6:Y6 (PCE = 15.86%) and PM6:BTMe-C8-2F (PCE = 11.98%). This work provides more insight into the role of introducing a fused ring electron acceptor with a high-lying LUMO energy level and complementary spectrum for simultaneously enhancing the VOC and JSC to promote the performance of ternary OSCs.
| S-EPMC10251189 | biostudies-literature
Project description:Y6 derivatives with asymmetric terminal groups have attracted considerable attention in recent years. However, the effects of the asymmetric modification of terminal groups on the photovoltaic performance of Y6 derivatives are not well understood yet. Therefore, we designed a series of Y6-based acceptors with asymmetric terminal groups by endowing them with various electron-withdrawing abilities and different conjugated rings to conduct systematic research. The electron-withdrawing ability of the Y6-D1 terminal group (substituted by IC-2F and IC-2NO2 terminals) is strongest, followed by Y6 (substituted by two same IC-2F terminals), Y6-D2 (substituted by IC-2F and 2-(4-oxo-4,5-dihydro-6H-cyclopenta[b]thiophen-6-ylidene)malononitrile terminals), Y6-D4 (substituted by IC-2F and indene ring), and Y6-D3 (substituted by IC-2F and thiazole ring). Computed results show that A-A stacking is the main molecular packing mode of Y6 and four other asymmetric Y6 derivatives. The ratios of A-A stacking face-on configuration of Y6-D1, Y6-D2, Y6-D3, Y6-D4, and Y6 are 51.6%, 55.0%, 43.5%, 59.3%, and 62.4%, respectively. Except for Y6-D1 substituted by the IC-2F and IC-2NO2 (the strongest electron-withdrawing capacity) terminal groups, the other three asymmetric molecules are mainly electron-transporting and can therefore act as acceptors. The open-circuit voltages of organic solar cells (OSCs) based on Y6-D2, Y6-D3, and Y6-D4, except for Y6-D1, may be higher than those of OSCs based on the Y6 acceptor because of their higher energy levels of lowest unoccupied molecular orbital (LUMO). PM6/Y6-D3 and PM6/Y6-D4 have better light absorption properties than PM6/Y6 due to their higher total oscillator strength. These results indicate that Y6-D3 and Y6-D4 can be employed as good acceptors.
| S-EPMC10572497 | biostudies-literature
Project description:Achieving precise spectral and temporal light manipulation at the nanoscale remains a critical challenge in nanophotonics. While photonic bound states in the continuum (BICs) have emerged as a powerful means of controlling light, their reliance on geometrical symmetry breaking for obtaining tailored resonances makes them highly susceptible to fabrication imperfections, and their generally fixed asymmetry factor fundamentally limits applications in reconfigurable metasurfaces. Here, we introduce the concept of environmental symmetry breaking by embedding identical resonators into a surrounding medium with carefully placed regions of contrasting refractive indexes, activating permittivity-driven quasi-BIC resonances (ε-qBICs) without altering the underlying resonator geometry and unlocking an additional degree of freedom for light manipulation through active tuning of the surrounding dielectric environment. We demonstrate this concept by integrating polyaniline (PANI), an electro-optically active polymer, to achieve electrically reconfigurable ε-qBICs. This integration not only demonstrates rapid switching speeds and exceptional durability but also boosts the system's optical response to environmental perturbations. Our strategy significantly expands the capabilities of resonant light manipulation through permittivity modulation, opening avenues for on-chip optical devices, advanced sensing, and beyond.
| S-EPMC11327280 | biostudies-literature
Project description:Enhancing the luminescence property without sacrificing the charge collection is one key to high-performance organic solar cells (OSCs), while limited by the severe non-radiative charge recombination. Here, we demonstrate efficient OSCs with high luminescence via the design and synthesis of an asymmetric non-fullerene acceptor, BO-5Cl. Blending BO-5Cl with the PM6 donor leads to a record-high electroluminescence external quantum efficiency of 0.1%, which results in a low non-radiative voltage loss of 0.178 eV and a power conversion efficiency (PCE) over 15%. Importantly, incorporating BO-5Cl as the third component into a widely-studied donor:acceptor (D:A) blend, PM6:BO-4Cl, allows device displaying a high certified PCE of 18.2%. Our joint experimental and theoretical studies unveil that more diverse D:A interfacial conformations formed by asymmetric acceptor induce optimized blend interfacial energetics, which contributes to the improved device performance via balancing charge generation and recombination.
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Project description:Volume electron microscopy, a powerful approach to generate large three-dimensional cell and tissue volumes at electron microscopy resolutions, is rapidly becoming a routine tool for understanding fundamental and applied biological questions. One of the enabling factors for its adoption has been the development of conventional fixation protocols with improved heavy metal staining. However, freeze-substitution with organic solvent-based fixation and staining has not realized the same level of benefit. Here, we report a straightforward approach including osmium tetroxide, acetone and up to 3% water substitution fluid (compatible with traditional or fast freeze-substitution protocols), warm-up and transition from organic solvent to aqueous 2% osmium tetroxide. Once fully hydrated, samples were processed in aqueous based potassium ferrocyanide, thiocarbohydrazide, osmium tetroxide, uranyl acetate and lead acetate before resin infiltration and polymerization. We observed a consistent and substantial increase in heavy metal staining across diverse and difficult-to-fix test organisms and tissue types, including plant tissues (Hordeum vulgare), nematode (Caenorhabditis elegans) and yeast (Saccharomyces cerevisiae). Our approach opens new possibilities to combine the benefits of cryo-preservation with enhanced contrast for volume electron microscopy in diverse organisms.
| S-EPMC9393620 | biostudies-literature
Project description:In non-fullerene organic solar cells, the long-range structure ordering induced by end-group π-π stacking of fused-ring non-fullerene acceptors is considered as the critical factor in realizing efficient charge transport and high power conversion efficiency. Here, we demonstrate that side-chain engineering of non-fullerene acceptors could drive the fused-ring backbone assembly from a π-π stacking mode to an intermixed packing mode, and to a non-stacking mode to refine its solid-state properties. Different from the above-mentioned understanding, we find that close atom contacts in a non-stacking mode can form efficient charge transport pathway through close side atom interactions. The intermixed solid-state packing motif in active layers could enable organic solar cells with superior efficiency and reduced non-radiative recombination loss compared with devices based on molecules with the classic end-group π-π stacking mode. Our observations open a new avenue in material design that endows better photovoltaic performance.
| S-EPMC7693324 | biostudies-literature
Project description:Cations and anions are replaced with Fe, Mn, and Se in CZTS in order to control the formations of the secondary phase, the band gap, and the micro structure of Cu2ZnSnS4. We demonstrate a simplified synthesis strategy for a range of quaternary chalcogenide nanoparticles such as Cu2ZnSnS4 (CZTS), Cu2FeSnS4 (CFTS), Cu2MnSnS4 (CMTS), Cu2ZnSnSe4 (CZTSe), and Cu2ZnSn(S0.5Se0.5)4 (CZTSSe) by thermolysis of metal chloride precursors using long chain amine molecules. It is observed that the crystal structure, band gap and micro structure of the CZTS thin films are affected by the substitution of anion/cations. Moreover, secondary phases are not observed and grain sizes are enhanced significantly with selenium doping (grain size ~1 μm). The earth-abundant Cu2MSnS4/Se4 (M = Zn, Mn and Fe) nanoparticles have band gaps in the range of 1.04-1.51 eV with high optical-absorption coefficients (~104 cm-1) in the visible region. The power conversion efficiency of a CZTS solar cell is enhanced significantly, from 0.4% to 7.4% with selenium doping, within an active area of 1.1 ± 0.1 cm2. The observed changes in the device performance parameters might be ascribed to the variation of optical band gap and microstructure of the thin films. The performance of the device is at par with sputtered fabricated films, at similar scales.
| S-EPMC5066312 | biostudies-literature