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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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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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Highly Stable Red Quantum Dot Light Emitting Diodes with Long T <sub/>95</sub> Operation Lifetime
摘要： Quantum dot light-emitting diodes (QLEDs) with excellent performances such as external quantum efficiency (EQE) and lifetime have almost met the requirement of low brightness display. However, the short operation lifetime under high brightness limits the application of QLEDs in outdoor displays and lightings. Herein, we report a highly efficient, stable red QLED by using of lithium and magnesium co-doped as well as magnesium oxide shell-coated zinc oxide nanoparticle layer as electron transport layer (ETL). The optimized QLED has a high peak EQE of 20.6%, a low efficiency roll-off at high current, and a remarkably long lifetime T95 > 11000 h at 1000 cd m-2, which indicates the realization of the most stable red QLED up to now. The improvement in the long-term stability of the QLED is attributed to the use of co-doped and shell-coated zinc oxide ETL with reduced electron injection to improve the charge balance in device.
关键词： EQE,QLEDs,electron transport layer,ETL,magnesium oxide shell-coated zinc oxide,Quantum dot light-emitting diodes,external quantum efficiency,lithium and magnesium co-doped,ZLMO@MO,lifetime
更新于2025-09-23 15:21:01
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Mg-Doped ZnO Nanoparticle Films as the Interlayer between the ZnO Electron Transport Layer and InP Quantum Dot Layer for Light-Emitting Diodes
摘要： Because the wide emission spectrum tunability which range from the visible region to the near-infrared, InP based colloidal quantum dots (QDs) show great promise for use in next-generation full-color displays and solid state lighting. The performance-improved InP QD based light-emitting devices (QLEDs) were fabricated by using Mg doped-ZnO nanoparticles (ZnMgO NPs) as an interlayer between ZnO electron transport layer and active InP QD layer. It is found that ZnMgO NPs can reduce electron injection and suppress exciton quenching which is attributed to the improvement of charge balance in the devices. We successfully demonstrated higher maximum current efficiencies of 5.46 and 5.91 cd/A than the references (2.31 and 2.36 cd/A) without the ZnMgO NP layer in highly efficient red and green QLEDs, respectively. These results signify an effective approach to improve heavy-metal-free QLEDs for commercial applications.
关键词： InP quantum dots,Mg doped-ZnO,electron transport layer,light-emitting diodes,charge balance
更新于2025-09-23 15:21:01
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[IEEE 2019 12th International Conference on Developments in eSystems Engineering (DeSE) - Kazan, Russia (2019.10.7-2019.10.10)] 2019 12th International Conference on Developments in eSystems Engineering (DeSE) - The Effects of Al-Doped ZnO Layer on the Performance of Organic Solar Cell
摘要： The interface properties as well as the solar cell properties of inverted organic solar cells based on PCDTBT:PCBM blends were investigated using sol-gel aluminum doped ZnO as electron transport layers. The effects of Al concentration on the optical, structural and morphological properties of AZO layer were investigated. The results indicate that Al concentration has influenced the grain size growth leading to different surface morphology. High doping concentration resulted in higher charge carrier density and wider band gap. Using AZO layers in organic solar cell has increased their performance; the best performance was observed for the device with 0.5% Al-doped ZnO layer with efficiency of 3.24%, short circuit current density of 8.82mA.cm-2, fill factor of 0.46% and open circuit voltage of 0.81V, whereas the reference device has exhibited an efficiency of 2.9%, short circuit current density of 7.6mA.cm-2, fill factor of 0.48 % and open circuit voltage of 0.785V.
关键词： Electron Transport layer,PCDTBT:PCBM,Organic solar cell,AZO thin films
更新于2025-09-23 15:21:01
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A two-fold engineering approach based on Bi2Te3 flakes towards efficient and stable inverted perovskite solar cells
摘要： Perovskite solar cells (PSCs) are currently the leading thin-film photovoltaic technology owing to their high power conversion efficiency (PCE), as well as their low-cost and facile manufacturing process. Two-dimensional (2D) materials have been reported to improve both the PCE and the stability of the PSCs when incorporated across the device’s layered configuration. Hereby, a two-fold engineering approach is implemented in inverted PSCs by using ultra-thin Bi2Te3 flakes, i.e.: (1) to dope the electron transport layer (ETL) and (2) to form a protective interlayer above the ETL. Thorough steady-state and time-resolved transport analyses reveal that our first engineering approach improves the electron extraction rate and thus the overall PCE (+8% vs. reference cells), as a result of the favourable energy level alignment between the perovskite, the ETL and the cathode. Moreover, the Bi2Te3 interlayer through the second engineering approach, facilitates further the electron transport and in addition protects the underlaying structure against chemical instability effects leading to enhanced device’s performance and stability. By combining the two engineering approaches, our optimised PSCs reach a PCE up to 19.46% (+17% vs. reference cells) and retain more than 80% of their initial PCE, after the burn-in phase, over 1100 h under continous 1 Sun illumination. These performances are among the highest reported in literature for inverted PSCs.
关键词： electron transport layer,Perovskite solar cells,Bi2Te3 flakes,stability,power conversion efficiency
更新于2025-09-23 15:21:01
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Al-, Ga-, Mg-, or Li-doped zinc oxide nanoparticles as electron transport layers for quantum dot light-emitting diodes
摘要： Colloidal quantum dots and other semiconductor nanocrystals are essential components of next-generation lighting and display devices. Due to their easily tunable and narrow emission band and near-unity fluorescence quantum yield, they allow cost-efficient fabrication of bright, pure-color and wide-gamut light emitting diodes (LEDs) and displays. A critical improvement in the quantum dot LED (QLED) technology was achieved when zinc oxide nanoparticles (NPs) were first introduced as an electron transport layer (ETL) material, which tremendously enhanced the device brightness and current efficiency due to the high mobility of electrons in ZnO and favorable alignment of its energy bands. During the next decade, the strategy of ZnO NP doping allowed the fabrication of QLEDs with a brightness of about 200 000 cd/m2 and current efficiency over 60 cd/A. On the other hand, the known ZnO doping approaches rely on a very fine tuning of the energy levels of the ZnO NP conduction band minimum; hence, selection of the appropriate dopant that would ensure the best device characteristics is often ambiguous. Here we address this problem via detailed comparison of QLEDs whose ETLs are formed by a set of ZnO NPs doped with Al, Ga, Mg, or Li. Although magnesium-doped ZnO NPs are the most common ETL material used in recently designed QLEDs, our experiments have shown that their aluminum-doped counterparts ensure better device performance in terms of brightness, current efficiency and turn-on voltage. These findings allow us to suggest ZnO NPs doped with Al as the best ETL material to be used in future QLEDs.
关键词： electron transport layer,doping,zinc oxide nanoparticles,light-emitting diodes,quantum dots
更新于2025-09-23 15:21:01
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Charge-transport layer engineering in perovskite solar cells
摘要： Photovoltaic (PV) technology that directly converts the solar energy into electrical energy, is regarding as one of the most promising utilization technologies of renewable and clean energy sources. Nowadays, developing low-cost and highly efficient PV technology is a hot research topic both for academia and industry. In this context, perovskite solar cells (PSCs) with metal halide perovskites [ABX3, A = CH3NH3+ (MA+), or CH(NH2)2+ (FA+), Cs+; B = Pb2+, Sn2+; X = Cl?, Br?, I?] as light harvesting material, is in the spotlight due to its easy fabrication process and high power conversion efficiency (PCE) [1,2]. To date, the certified PCE has been already pushed up to 25.2% (https://www.nrel.gov/pv/module-efficiency.html), making PSC an auspicious candidate for a new generation of photovoltaics. In future days, how to eliminate the non-essential charge carrier recombination in the device, further push the PCE approaching the Shockley-Queisser theoretical efficiency limit (~35%) and enhance the device stability, will be formidable challenges and the focus in the next stage of research work.
关键词： electron transport layer,hole transport layer,charge-transport layer,perovskite solar cells,power conversion efficiency
更新于2025-09-23 15:19:57
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Performance optimization of CH3NH3Pb(I1-xBrx)3 based perovskite solar cells by comparing different ETL materials through conduction band offset engineering
摘要： Numerical simulations can provide the physical insights into the carrier transport mechanism in the solar cells, and the factors influencing their performance. In this paper, perovskite solar cell (PSC) based on the mixed perovskite (CH3NH3Pb(I1-xBrx)3 has been numerically simulated using the SCAPS simulator. A comparative analysis of different electron transport layers (ETLs) based on their conduction band offsets (CBO) has been performed, while Spiro-OMeTAD was used as a hole transport layer (HTL). Among the proposed ETLs, CdZnS performed better and demonstrated the power conversion efficiency (PCE) of 25.20%. Also, the PCE of the PSC has been optimized by adjusting the doping concentrations in the ETL, Spiro-OMeTAD layer, and the thickness of the perovskite light absorber layer. It was found that the doping concentration of 1021 cm?3 for the CdZnS based ETL and 1020 cm?3 for Spiro-OMeTAD are the optimum concentrations values for demonstrating enhanced efficiency. A 600 nm thick perovskite layer has found to be appropriate for the efficient PSC design. For the initial guessing and numerical model validation, the photovoltaic data of a very stable (over one year with PCE ~13%) n-i-p structured (ITO/TiO2/CH3NH3Pb(I1-xBrx)3/Spiro-OMeTAD/Au) PSCs was used. These numerically simulated results signify the optimum performance of the photovoltaic device that can be further implemented to develop the highly efficient PSCs.
关键词： The power conversion efficiency,Hole transport layer,Electron transport layer,Conduction band offset engineering,SCAPS,Perovskite solar cell
更新于2025-09-23 15:19:57