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Unraveling the Complex Nanomorphology of Ternary Organic Solar Cells with Multimodal Analytical Transmission Electron Microscopy
摘要： Elucidating the complex materials distribution in the active layers of ternary organic solar cells is one of the greatest challenges in the field of organic photovoltaics. Knowledge of the nanomorphology is key to understanding photophysical processes (e.g. charge separation, adjustment of the recombination mechanism as well as suppression of the radiationless and energetic losses) and thus improving the device performance. Here, we demonstrate for the first time the successful discrimination and spatial mapping of the active layer components of a ternary organic solar cell using analytical transmission electron microscopy. The material distribution of all three organic components was successfully visualized by multimodal imaging using complementary electron energy loss signals. A complete picture of the morphological aspects could be gained by studying the lateral and cross-sectional morphology as well as the morphology evolution as a function of the mixing ratio of the polymers. Finally, a correlation between the morphology, photophysical processes and device performance of the ternary and the reference binary system was achieved, explaining the differences of the power conversion efficiency (PCE) between the two systems.
关键词： device performance,EFTEM,morphology,TEM,Ternary organic solar cells
更新于2025-09-23 15:21:01
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Probe and Control of the Tiny Amounts of Dopants in BHJ Film Enable Higher-Performance Polymer Solar Cells
摘要： In order to achieve efficient doping in polymer solar cell (PSC), the dopant needs to be selectively located in the binary components of bulk heterojunction (BHJ) film according to its polarity. The rarely studied n-type dopant is thoroughly examined in a simplified planar heterojunction (PHJ) device to address its favored location in the active layer. Results show that the n-dopant distributing in the acceptor layer or at the donor/acceptor interface produces enhanced device performance, whereas it harms the device when locating in the donor layer. Based on the results, the benefit of n-type doping is then transferred to the high-efficient BHJ devices via a sequential coating procedure. The performance improvement is closely linked with the variation of dopant’s location in the BHJ film, which is carefully examined by the synchrotron techniques with delicate chemical sensitivity. More interestingly, the sequential coating procedure can be easily extended to the p-doped device only by changing the dopant’s polarity in the middle layer. These findings pave the way of ambipolar doping in PSCs and make performance improvement by molecular doping within expectation.
关键词： molecular doping,Polymer solar cell,doped morphology,n-type doping,ternary blend solar cell
更新于2025-09-23 15:21:01
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Ideal alloys of two donor isomers with non-covalently conformational locking for ternary organic solar cells
摘要： Ternary organic solar cells (OSCs) based on the alloy model have great potential in maximizing the improvement of device performance due to the probability of simultaneously enhancing the photocurrent through morphology optimization and improving open circuit voltage (Voc) by energy level adjustment. However, rationally designing compatible materials and constructing an effective alloy remain difficult. In this manuscript, two donor isomers, BT-TO-ID and BT-OT-ID with non-covalently conformational locking of alkoxy groups at different position, were designed and synthesized to obtain an ‘‘ideal alloy’’. A linearly tunable Voc was observed between the Voc limitation of binary blends with the changes of the composition across the full range, indicating the behavior of an ideal alloy in the ternary blends. A face-on molecular packing and an appropriate phase separation was observed in the ternary blends due to the strong interactions between the two isomers, which facilitated charge transport and charge recombination suppression. Notable improvements of 76% and 29% in device performance were obtained for the ternary blends compared with BT-OT-ID based and BT-OT-ID based binary devices, respectively. Therefore, this work provided a probable molecular design strategy to guide the construction of an effective alloy in ternary OSCs.
关键词： Open circuit voltage,Non-covalently conformational locking,Alloy model,Device performance,Molecular packing,Phase separation,Ternary organic solar cells,Donor isomers
更新于2025-09-23 15:21:01
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Enhancement of photovoltaic performance in immiscible ternary blends
摘要： Ternary-blend active layers composed of one donor and two acceptors have been actively studied to enhance the power conversion efficiency (PCE) of organic solar cells (OSCs), and numerous advances in miscible ternary blends have been reported. In the present study, we report an unusual behavior of immiscible ternary blends with respect to the enhancement of PCE and stability of OSC devices. The active layer consists of three relatively easily synthesizable materials: poly[(4,8-bis(5-(2-ethylhexyl)thiophen2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)-alt-((5-bromo-4-octylthiazol-2-yl)thiophene-2,5-diyl)] (POTz) as a donor, 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) as a nonfullerene acceptor, and [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) fullerene. The POTz:IDIC blends showed a typical bicontinuous and uniform nanomorphology; however, the addition of PC70BM to the POTz:IDIC blends led to immiscible domains. When small amounts of PC70BM (8.3–16.7 w%) were incorporated into POTz:IDIC:PC70BM blends, the POTz:IDIC formed a continuous phase and small PC70BM domains were uniformly dispersed into the continuous phase, which resembled raisin bread. The dispersed PC70BM domains enhanced the electron mobility of the POTz:IDIC:PC70BM film and promoted charge balance between holes and electrons, resulting in an enhanced short-circuit current density and fill factor. Notably, the ternary blends with PC70BM exhibited the improved long-term stability in light-soaking tests by reducing the burn-in loss of the devices.
关键词： semi-crystalline polymer,organic solar cells,continuous phase,immiscible blends,ternary blends
更新于2025-09-23 15:21:01
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The Balance between Energy Transfer and Exciton Separation in Ternary Organic Solar Cells with Two Conjugated Polymer Donor
摘要： Ternary strategy as a straightforward way for organic solar cells (OSCs) to improve the device performance attracts many interests in the field. The ternary strategy usually focuses on processing the third light-absorbing material owning a complementary absorption to the binary system. However, studying the third component with similar absorption spectra to the binary counterpart is equally essential to understand the in-depth mechanism of the performance improvement from the third component. In this work, we filled up this blank and derived a type of ternary device consisting of two conjugated polymer donor materials of PTB7-Th and PffBT4T-2OD and non-fullerene acceptor material of IEICO-4F. The average PCE value of the optimized ternary device reached 12.1%, which is around 16% higher than its PTB7-Th:IEICO-4F binary counterpart. Even the third component of PffBT4T-2OD containing a similar absorption spectrum with PTB7-Th, it was found that the Jsc increase contributes to the primary performance enhancement. Further investigations indicate that the Jsc increase in the optimized ternary device mainly came from the improved light absorption ability, current extraction process, charge transport process, and suppressed non-radiative recombination. Moreover, there is a balance found between the exciton separation process and the energy transfer process when optimizing ternary blend ratios. The optimized ternary device is suspected to reach this balance point and thus exhibits the enhancement in device performance. Morphology investigation reveals that the addition of PffBT4T-2OD can tune the morphology and increase the crystallinity in the active layer. The optimized ternary blend shows a well-mixed donor and acceptor morphology with small domain size and slightly increased crystallization, which further explained its best device performance.
关键词： non-fullerene,energy transfer,exciton separation,organic solar cells,ternary,crystallization,conjugated polymer
更新于2025-09-23 15:21:01
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Hierarchical 3D VO2/ZnV2O4 microspheres as an excellent visible light photocatalyst for CO2 reduction to solar fuels
摘要： The photocatalytic reduction of CO2 has a great potential to produce fuels and chemicals, as well as, it reduces CO2 emission and addresses the environmental issues. To date single metal based catalysts still su?er from lower e?ciency, uncontrollable selectivity and instability. In this study, hierarchical microspheres (HMs) of ZnV2O4 with VO2 impurity were synthesized through the single step reduction process, to explore highly e?cient photocatalyst towards visible light responsive photocatalytic CO2 reduction. HMs of ZnV2O4 were successfully synthesized with mesoporous structure, higher surface area and functional under visible light irradiations. The ?1 were obtained over ZnV2O4 synthesized after highest yield of CO and CH3OH of 378 and 202 μmole g-cat 24 h of reaction time, respectively. The performance of optimized 3D HMs of ZnV2O4 for CO and CH3OH pro-duction was 2.30 folds and 10.7 folds higher than using ZnO/V2O5 composite sample, respectively. Other products detected with appreciable amounts were CH4 and C2H6. This reveals, HMs structure of ZnV2O4 not only allows the transfer of electrons towards CO2, but also provides short pathways for electron transfer and empty space in the microspheres will serve as the reservoirs to store the electrons, hence leading to enhanced photo-activity. In addition, VO2 presents in the sample further contribute to enhance performance of ZnV2O4 HMs due to enabling e?cient charge carrier separation. The prolong stability of ZnV2O4 in the CO2 reduction system con?rmed that 3D HMs structure provides controllable selectivity and stability. This brings to conclusions that fabrication of hierarchical structures will stimulate further development towards high performance photo-cat-alysts for the photocatalytic CO2 reduction to solar hydrocarbon fuels.
关键词： Hierarchical structure,CO2 reduction,Ternary metal oxide,Zinc vanadium oxide,3D microspheres of ZnV2O4,Hydrocarbon fuels
更新于2025-09-23 15:21:01
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Ag/αFe2O3-rGO novel ternary nanocomposites: synthesis, characterization, and photocatalytic activity
摘要： In this research, novel ternary Ag/αFe2O3-rGO nanocomposites with various contents of GO were synthesized via a facile one-pot hydrothermal method. Ag/αFe2O3-rGO nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometer (EDX), photoluminescence (PL) spectroscopy, and Fourier transform infrared (FTIR). The results showed that hematite nanoparticles and Ag nanoparticles were well decorated on the graphene surface. Photocatalytic activity of Ag/αFe2O3-rGO ternary nanocomposites and pure Ag/αFe2O3 was investigated for photodegradation of Congo red dye solution as a model pollutant under UV light irradiation. The ternary nanocomposite with 1.8 mg/ml GO aqueous solution concentration shows higher degradation efficiency under UV light irradiation than the pure Ag/αFe2O3 and the nanocomposites with other GO aqueous solution concentrations. It was observed that the adsorption of the dyes on the nanocomposites surface is dependent on the graphene content due to a decrease in the recombination rate, particles size, and increase charge carrier transfer. The results show that the Ag/αFe2O3-rGO nanocomposite can be used as an excellent photocatalytic material for degradation of Congo red dye in wastewater. A possible photocatalytic mechanism was proposed for degradation of Congo red dye.
关键词： ternary nanocomposites,photocatalytic activity,graphene,Ag/αFe2O3-rGO
更新于2025-09-23 15:21:01
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Deposition and characterization of earth abundant <scp>CuZnS</scp> ternary thin films by vacuum spray pyrolysis and fabrication of <scp>pa??</scp> CZS/ <scp>na??AZO</scp> heterojunction solar cells
摘要： We report fabrication of solar cell device <ITO/AZO/i-ZnO/CZS/Al> with Copper Zinc Sulfide (CZS) thin films as absorber layer. CZS thin films prepared using chemical spray pyrolysis technique at a pressure of 10?3 mbar at different substrate temperatures. Structural, morphological, optical, compositional and electrical properties of as prepared films are investigated. Structural analysis shows crystalline nature with mixed phase containing CuS-ZnS binary composite. Atomic Force Microscopy analysis shows the average particle size of 88 nm. Value of work function obtained from ultraviolet photoelectron spectroscopy is 4.58 eV. The band gap of the as-prepared films varies from 1.62 to 2.06 eV. Hall effect measurement proves the p-type nature for all the deposited films. Samples deposited at 350°C shows carrier concentration of 1021 cm?3 and electrical conductivity of 526 S cm?1. Solar cell device structure of <ITO/AZO/i-ZnO/CZS/Al> has been fabricated using the CZS sample deposited at 350°C. The cell parameters obtained are Voc = 0.505 V, Isc = 4.97 mA/cm2, FF = 64.28% and η = 1.6 ± 0.05%.
关键词： solar cell,heterojunction,ternary compound,thin film,absorber layer,vacuum spray pyrolysis
更新于2025-09-23 15:21:01
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Optical vibration modes in multi-layer quantum dots of polar ternary mixed crystals
摘要： Within the framework of the dielectric continuum approach and the modified random-element isodisplacement model, the optical vibration modes as well as the corresponding electron-phonon interactions in spherical multi-layer quantum dots (QDs) consisting of ternary mixed crystals (TMCs) are investigated in detail. The dispersion relation and electron-phonon interaction Hamiltonian are obtained. As applications of the present theory, the numerical calculations for the ZnS/ZnxCd1-xS/ZnS and GaAs/AlxGa1-xAs/GaAs QDs are performed and discussed. Considering the "one-mode" and "two-mode" behaviors of the TMCs, the results show that there are 5 and 7 branches of interface/surface optical (IO/SO) phonon modes in the two systems, respectively. It is found that the effects of TMCs have a remarkable influence on the optical phonon frequencies and the electron-phonon interactions. The results also reveal that the presence of the cap layer introduces significant influence on the TMCs effects of optical phonon in multi-layer QDs. We hope that our theoretical results can stimulate further investigations of related photoelectric properties, as well as device applications in multi-layer QDs consisting of TMCs.
关键词： ternary mixed crystal,electron-phonon interaction,optical vibration mode,multi-layer quantum dot
更新于2025-09-23 15:21:01
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Ternary Hierarchical Cu <sub/>7</sub> S <sub/>4</sub> /TiO <sub/>2</sub> /CoCr-LDH Heterostructured Nanorod Arrays with Multiphase Reaction Interfaces for More Efficient Photoelectrochemical Water Splitting
摘要： Fabricating hierarchical and highly matched heterostructure with large surface areas and multiple interfaces is an effective approach to enhancing the photoelectrochemical performance. Here, well-aligned hierarchical Cu7S4/TiO2/CoCr-layered double hydroxide (LDH) nanorod arrays are reported, aiming at accelerating charge separation and transfer kinetics. The modifications of Cu7S4 and CoCr-LDH based on TiO2 have endowed the photoanode a surprising enhancement in both ultraviolet light absorption and charge separation efficiency due to highly matched band alignment. The formation of heterojunction is an effective strategy to prevent photocorrosion of Cu7S4 by attaching protective layers on Cu7S4. Moreover, other than the hierarchical morphology with enlarged active surface areas would provide sufficient active sites for the water oxidation processes and pore channels for the gas escaping, owing to the special band alignment of three components, multiple reaction interfaces are produced and involved in the water splitting process, since the photoinduced holes for water oxidation are simultaneously distributed in CoCr-LDH and Cu7S4. As expected, this synergistic effect in this ternary Cu7S4/TiO2/CoCr-LDH heterogeneous photoanode gives rise to a largely enhanced photoconversion efficiency (0.58% at 0.6 V) and photocurrent density (2.04 mA cm?2 at 1.23 V).
关键词： 3D hierarchical nanorod arrays,Cu7S4/TiO2/CoCr-LDH,ternary heterostructure,highly matched band alignment,photoelectrochemical water splitting
更新于2025-09-23 15:21:01