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Solvent Effects on the Interface and Film Integrity of Solution-Processed ZnO Electron Transfer Layers for Quantum Dot Light Emitting Diodes
摘要： Solution-processed ZnO nanoparticle thin film is widely used as the electron transport layers (ETLs) in quantum dot light emitting diodes (QLEDs). While the ZnO nanoparticles (NPs) synthesis process has been thoroughly optimized, very few studies have focused on exploring how the solvents for dispersing the NPs affect the film-forming process, which has profound effects on the film quality and functionality as ETLs. Herein, we present a comprehensive investigation on the impact of the dispersing agent on the materials and carrier transport properties of spin-coated ZnO NP thin films. The first four members of the alkanol family, which show considerably different viscosities and volatilities, were used in this study. ZnO NP thin films deposited with different alcohols were used as the ETLs of the QLED structure and the optoelectronic performances of the devices are compared. Alcohols with high viscosity are found to cause NP agglomerations which roughen the film surface and lead to significant leakage current. Nano-cracks in the ZnO NP film are observed when a highly volatile solvent is used due to the vigorous bursts of vapor during solvent evaporation. Our results show that proper solvent can improve the surface roughness and compactness of the solution-processed ZnO films and lead to a 30% difference in the current efficiency of QLEDs. The findings here clearly indicate the important roles of the dispersing agent in the formation of high-quality NP-based thin films, which can be an important guidance for achieving high performances in QLEDs as well as a variety of solution-based devices.
关键词： Interface,Solvent,QLEDs,Electron transport layer,ZnO
更新于2025-11-21 11:01:37
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2D Photonic Crystal Nanodisk Array as Electron Transport Layer for Highly Efficient Perovskite Solar Cells
摘要： Perovskite solar cells (PSCs) are currently exhibiting reproducible high efficiency; the manufacturing of low cost, scalable electron transport layers (ETLs) is becoming increasingly important. However, this remains a challenge for electron transport layers that exhibit excellent optical/electrical properties while being a thin film of simple morphology. Here we demonstrate the PSC of a 2D photonic crystal nanodisk (ND) array ETL that is compact, but greatly enhances light harvesting. The ND array is fabricated by nanosphere lithography using a monolayer of self-assembled polymer spheres as a physical mask. We fabricate ND arrays of various lattice constants simply by controlling the size of the polymer spheres. Optimal ND arrays exhibit strong forward scattering and optical confinement effects, greatly improving light harvesting in the perovskite layer. We also observe that the ND array improves charge transport by reducing contact resistance with the perovskite layer. ND array ETL PSCs reach 19% maximum power conversion efficiency, with low photocurrent-voltage hysteresis and stable photocurrent output.
关键词： optical confinement,2D photonic crystals,nanodisk array,electron transport layer,perovskite solar cells,forward scattering
更新于2025-11-19 16:46:39
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A systematic approach to ZnO nanoparticle-assisted electron transport bilayer for high efficiency and stable perovskite solar cells
摘要： Minimizing the interface loss of perovskite solar cells is critical to achieving high photovoltaic performance, and intensive research is underway on interfacial engineering in this regard. In this work, we introduce a ZnO nanoparticles (ZnO NPs) interlayer between phenyl-C61-butyric acid methyl ester (PCBM) and a metal electrode in order to reduce the interface loss due to charge recombination and device degradation, and also investigate the dependence of device performance on the thickness and morphology of the PCBM and PCBM/ZnO electron transport bilayer. After achieving optimized PCBM and ZnO thickness, the PCBM/ZnO bilayer-based devices reached an average power conversion efficiency of 15.63% (Max. 16.39%) with an open circuit voltage of 1.05 V, short circuit current density of 18.69 mA cm-2, and fill factor of 79.95%. In addition, hysteresis behavior and atmospheric stability are significantly improved by the incorporation of a PCBM/ZnO bilayer. Therefore, the implementation of a PCBM/ZnO electron transport bilayer is a promising approach toward achieving a high-efficiency PSC with stable power output (low J-V hysteresis) and durability.
关键词： ZnO nanoparticles,interfacial engineering,stable perovskite solar cells,interface loss,high-efficiency perovskite solar cells,electron transport bilayer
更新于2025-11-19 16:46:39
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Hierarchical ZnO microspheres embedded in TiO2 photoanode for enhanced CdS/CdSe sensitized solar cells
摘要： Control of structural and compositional characteristics of photoanodes is a crucial step toward rapid transport of charges and high efficiency loading of dye or quantum dots in case of solar cell application. A hierarchical ZnO microspheres (ZMS) and TiO2 hybrid photoanode film was prepared for improved CdS/CdSe quantum dot sensitized solar cells (QDSCs). The addition of ZMS into TiO2 electrode films resulted in both increased short circuit current density (Jsc) and open circuit voltage (Voc). Such an improvement is ascribed to the increased light harvesting owing to scattering by ZMS and the reduced charge recombination due to the surface modification. TiO2/ZMS hybrid photoanode displays superior charge injection/transport performance due to the ZMS with unique hierarchical structure, providing charge transfer continuity and multiple electron transport channels for timely electron transport. As a result, the Jsc, Voc, and the photovoltaic conversion efficiency (PCE) were all remarkably enhanced with the insertion of hierarchical ZMS though varied appreciably with the amount of ZMS. Thus, the designed TiO2/ZMS heterostructure based QDSCs with an optimizing ZMS ratio of 20 wt% achieved a PCE of 5.99%, which is about 35% increase of the efficiency for the devices without ZMS (4.45%).
关键词： electron transport,ZnO microspheres,charge injection,quantum dot-sensitized solar cells,photoanode,light scattering
更新于2025-11-14 17:04:02
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Hierarchical TiO <sub/>2</sub> microspheres composed with nanoparticle-decorated nanorods for the enhanced photovoltaic performance in dye-sensitized solar cells
摘要： Hierarchical TiO2 microspheres composed of nanoparticle-decorated nanorods (NP-MS) were successfully prepared with a two-step solvothermal method. There were three benefits associated with the use of NP-MS as a photoanode material. The decoration of nanoparticles improved the specific surface area and directly enhanced the dye loading ability. Rutile nanorods serving as electron transport paths resulted in fast electron transport and inhibited the charge recombination process. The three-dimensional hierarchical NP-MS structure supplied a strong light scattering capability and good connectivity. Thus, the hierarchical NP-MS combined the beneficial properties of improved scattering capability, dye loading ability, electron transport and inhibited charge recombination. Attributed to these advantages, a photoelectric conversion efficiency of up to 7.32% was obtained with the NP-MS film-based photoanode, resulting in a 43.5% enhancement compared to the efficiency of the P25 film-based photoanode (5.10%) at a similar thickness. Compared to traditional photoanodes with scattering layers or scattering centers, the fabrication process for single layered photoanodes with enhanced scattering capability was very simple. We believe the strategy would be beneficial for the easy fabrication of efficient dye-sensitized solar cells.
关键词： electron transport,dye-sensitized solar cells,solvothermal method,Hierarchical TiO2 microspheres,photovoltaic performance
更新于2025-11-14 17:04:02
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Electron Transport Improvement of Perovskite Solar Cell via ZIF-8 Derived Porous Carbon Skeleton
摘要： To improve electron transport rate of perovskite solar cell, ZIF-8 derived porous carbon skeleton layer is prepared by carbonizing the ZIF-8 thin film on conducting glass as the electron transport skeleton of perovskite solar cell. Polyvinyl pyrrolidone is added during the synthesis of ZIF-8 to reduce the particle size of ZIF-8 and decrease the carbonization temperature below 600°C. The porous structure of ZIF-8 is mainly reserved at the optimized carbonization temperature. Then TiO2 nanoparticles are deposited on the surface of porous carbon skeleton to form an electron transport layer of perovskite solar cell with the structure of FTO/ZIF-8 derived porous carbon layer/TiO2/Perovskite/Spiro-OMeTAD/Au. Due to the good conductivity of the ZIF-8 derived porous carbon skeleton, the photogenerated electron transport rate of perovskite solar cell is increased. At the same time, the porous structure of ZIF-8 derived carbon layer increases the contact area between the perovskite layer and the TiO2 layer to favor separation of photogenerated charges. Therefore, the light-to-electric conversion efficiency of CH3NH3PbI3 perovskite solar cell is enhanced from 14.25% to 17.32%.
关键词： Electron transport,Increase of contact area,Porous carbon skeleton,Good conductivity,Polyvinyl pyrrolidone,Perovskite solar cell,Metal organic frameworks
更新于2025-11-14 17:04:02
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Fabrication of peanut-like TiO2 microarchitecture with enhanced surface light trapping and high specific surface area for high-efficiency dye sensitized solar cells
摘要： The quality of TiO2 photoelectrode is critical to fabricate high-performance dye-sensitized solar cells (DSSCs), but constructing TiO2 microstructure with high exposure reactive facets and high specific surface area is still a challenge. Herein, we present a facile route for creating a novel peanut-like (PN) anatase TiO2 microstructure with high exposed (001) facet, enhanced light trapping and large specific surface area using a one-pot hydrothermal method without fluorion assistance. With the introduction of diethylenetriamine as shape controlling agent and two-phase interface by etherification reaction of isopropyl alcohol, anatase PN TiO2 microarchitecture consisted with ultrathin nanosheets can be successfully fabricated. The obtained PN TiO2 combines the advantages of high exposed reactive (001) facets and large specific surface area (180.8 m2/g). The PN TiO2 based DSSC exhibits an outstanding photovoltaic conversion efficiency up to 9.14%, which can attribute to larger dye loading, superior light scattering capability, higher electron collection efficiency, narrower bandgap as well as efficient electron injection, together with improved electron transport and reduced charge recombination due to the unique peanut-like microstructure. Our work demonstrates the potential of PN TiO2 for improving the performance of energy storage devices.
关键词： Dye sensitized solar cell,(001) facet,Titanium dioxide,Improved electron transport,Peanut-like structure
更新于2025-11-14 17:04:02
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Far-Red Spectrum of Second Emerson Effect: A Study Using Dual-Wavelength Pulse Amplitude Modulation Fluorometry
摘要： Non-additive enhancement of the photosynthesis excited by simultaneous illumination with far-red light and light of shorter wavelengths is called as “second Emerson effect”. Its action spectra are well-known as a photosynthetic yield’s dependence on light wavelength in red (630-690 nm) spectral region at a constant-wavelength far-red illumination near 700-715 nm. However, the opposite dependence of the photosynthetic yield’s of shorter constant-wavelength light (red or blue) on light wavelength in far-red (690-760 nm) spectral region was never studied. In this study the action spectrum of second Emerson effect was studied using a fast-Fourier dual-wavelength Pulse Amplitude Modulation (PAM) fluorometry. Chlorophyll fluorescence in ailanthus (Ailanthus altissima Mill.) leaves was excited with blue modulated light. Far-red induced decrease of fluorescence (fluorescence shift-FRIFS) was studied in response to illumination of leaves with a background light from 690 to 760 nm (10 nm step), calculating FRIFS = (F0-Fs)/F0, where F0-fluorescence measured without and Fs-with far-red light. Maximum FRIFS was observed at 720 nm (11.8%), but it still remained considerable at 740, 750 nm and a low FRIFS values were revealed at 690 and even at 760 nm. Measurements carried out with blue saturating flashes during and after far-red illumination showed the increase of quantum yield of Photosystem II (PSII), calculated as Fv/Fm at 720 nm background light. FRIFS had lower values under excitation with red modulating light. It is concluded that FRIFS is a result of a photochemical quenching caused by an additional selective far-red excitation of PSI in conditions when PSII is preferably excited by blue light thus leading the PSI to limit non-cyclic electron flow. The contradiction between the known absorption spectra of PSI-light harvesting complex I and the observed action spectrum of second Emerson effect (FRIFS spectrum) is discussed.
关键词： Photosystem II,Ailanthus Altissima,Photosystem I,Second Emerson Effect,Fast-Fourier PAM-Fluorometry,Far-Red Light,Thylakoid Electron Transport
更新于2025-11-14 15:30:11
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Free Exciton Absorptions and Quasi-reversible Redox Actions in Polypyrrole–Polyaniline–Zinc Oxide Nanocomposites as Electron Transporting Layer for Organic Light Emitting Diode and Electrode Material for Supercapacitors
摘要： The ternary nanocomposite comprised of PPY–PANI (polypyrrole–polyaniline) copolymer and zinc oxide (ZnO), synthesized by implying chemical oxidative polymerization of pyrrole monomer in presence of ammonium persulfate as oxidant with varying ZnO concentrations. The shifting of bands and their corresponding change in nano-strain of as-prepared PPY–PANI–ZnO nanocomposite of varying concentration was confirmed by the Fourier transform inferred spectroscopy (FTIR). The surface morphological images of PPY–PANI–ZnO nanocomposites revealed the nano-flake like structure attributed to the embodiment of ZnO and increase in agglomeration was detected with the increasing concentration of ZnO. The optimized reduction in band gap up to ~ 1.02 eV and red-shift of absorption edge of ZnO in visible region side was detected for 10% PPY–PANI–ZnO nanocomposite. The relatively slow decay component and higher non radiative electron–hole recombination rate showed the better electron transport properties with chromaticity in ideal blue region for 10% PPY–PANI–ZnO nanocomposite. The higher current density ~ 7.95 A/cm2, high dielectric constant ~ 1960 at 373 K, high reduction potential ~ + 0.687 V with high specific capacitance (~ 436.14 F/g) at 10 mV s?1 and better thermal firmness was observed for 10% PPY–PANI–ZnO nanocomposite. The relatively high discharge time ~ 2600 s and high power density with meagre loss in energy density at high current density was also observed for 10% PPY–PANI–ZnO nanocomposite. These robust properties confirmed that the proposed 10% PPY–PANI–ZnO nanocomposite could be employed as electron transporting material for OLEDs as well as for high performance and efficient supercapacitors.
关键词： PPY–PANI–ZnO nanocomposites,Electrochemical performance,Chemical oxidative polymerization,PL,Electron transport layer
更新于2025-09-23 15:23:52
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Electron transport through phenylene sandwiched between zigzag graphene nanoribbons
摘要： We study systematically the electron transport through a phenylene rotor with an axis of atomic carbon chain (CPC) connected to twofold symmetric electrodes of nonmagnetic zigzag graphene nanoribbons. The density functional theory combined with the nonequilibrium Green’s function method is employed for the simulation. The CPC rotor is conductive with parabolic I–V characteristic when its ring is coplanar with the electrodes. Its rotation modulates the symmetry of its electron states and their matching to the states in the electrodes. The I–V curve then becomes characterized by sharp peaks with strong negative differential resistance (NDR) in a large range of the rotation angle. The corresponding shift of transport modes in energy with the rotation opens a way to efficient and accurate manipulation of NDR.
关键词： Electron transport,Graphene,Zigzag nanoribbon,Phenylene
更新于2025-09-23 15:22:29