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Influence of baking temperature on relevant properties of sol-gel Ga-doped ZnO thin films annealed at low temperature
摘要： Ga-doped ZnO(GZO) transparent thin films were grown onto glass substrates by sol-gel based spin coating process. After each coating, the as-deposited film was thermally baked at different moderate temperatures ranging from 100°C to 250°C followed by calcinations at certain temperature lower than 400°C. Characterization were conducted on calcined samples using scanning electron microscope (SEM), X-ray diffraction (XRD), optical spectroscopy and Fourier transform infrared spectroscopy (FTIR). The influence of baking temperature on crucial properties including structural, morphological and optical properties of Ga-doped ZnO transparent thin films were extensively investigated. XRD patterns exhibited typical polycrystalline of hexagonal wurtzite structure of as-deposited thin films and baking temperature is considered as one of essential key parameters affecting the crucial properties of the prepared films.
关键词： Low temperature annealing,Ga-doped ZnO,Baking temperature,Spin coating
更新于2025-09-12 10:27:22
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Review of the fundamental issues in new generation high efficiency perovskite solar cells
摘要： This is a mini review of the fundamental issues in producing high efficiency solar cells. We have raised many important issues that limit the power conversion efficiency, and introduced the solutions in particular to perovskite solar cell structures. We supposedly estimate very high efficiencies over detailed balance or Schockley-Quessier limit up to 50 %, having applications such as tandem cells, light concentration, inter-band activities with deep levels, photon upconversion and quantum dots together with some unique processing systems.
关键词： Spin Coating,Organic elektronics,Thin film,Perovskite solar cells
更新于2025-09-12 10:27:22
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Optimization of a precursor-PbI2 layer by re-crystallization for efficiency improvement in perovskite solar cells
摘要： Due to good light absorption capability, ease of production process and high potential of large area fabrication, perovskite solar cells receive a wide attention around the scientific community. Factors affecting the efficiency of perovskite solar cells include moisture, perovskite solution purity, completeness of perovskite layer and perovskite crystal grain size. In this work, the investigation of crystallization process of PbI2 as precursor for methyl ammonium lead triodide (CH3NH3PbI3) photo-absorber layer has been carried out. The inverted structure of FTO/PEDOT: PSS/CH3NH3PbI3/PCBM/Ag perovskite devices is fabricated using the two-step spin-coating method. The pre-heated PbI2 solution is left at room temperature to re-crystallize at various crystallization time (0-60 h). It was discovered that the perovskite solar cell using 48 h of crystallization time provides the highest power conversion efficiency of 9.69%. Morphology and crystallinity of perovskite layer will be discussed in relation to photovoltaic properties.
关键词： re-crystallization,perovskite solar cells,two-step spin - coating method,inverted structure
更新于2025-09-12 10:27:22
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Enhanced photovoltaic performance and stability of planar perovskite solar cells by introducing dithizone
摘要： In the two-step spin-coating method, the crystallization and morphology of PbI2 film are essential for producing highly efficient and stable planar heterojunction (PHJ) perovskite solar cells. In this work, the dithizone (DTZ) molecules were introduced into PbI2 precursor to improve the performance of perovskite films. We found that adding DTZ was an effective method to retard the crystallization of PbI2 film and consequently, produced a high-quality perovskite film with pinhole-free, smoother, and fewer defects surface. Most importantly, the presence of residual DTZ in wet PbI2 film also assisted DMSO to slow down the growth of perovskite grains. By tuning the concentration of DTZ, the power conversion efficiency of the best performed cell has increased to 20.66% with negligible photocurrent hysteresis. Meanwhile, the best DTZ device offer an excellent stability, which retained 97% of the initial PCE after storage in the dark for approximately 24 days. We expect this controlled crystallization method could be further explored and provides a useful strategy to improve the performance of perovskite solar cells.
关键词： Planar heterojunction,Dithizone,Perovskite solar cells,Two-step spin-coating method,Chelating agents
更新于2025-09-12 10:27:22
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Strontium Chloride Passivated Perovskite Thin Films for Efficient Solar Cells with Power Conversion Efficiency over 21% and Superior Stability
摘要： Industrialization of perovskite solar cells (PSCs) is constrained by adverse stability in the air. Herein, we report an effective strontium chloride (SrCl2) passivation upon the HC(NH2)2-CH3NH3 (FA-MA) based perovskite thin films for the suppression of non-radiative recombination. Moreover, the recombination dynamics, crystallinity, carrier transport, morphology and the elemental stoichiometry of this film were systematically studied. By optimizing the concentration of SrCl2, the corresponding devices exhibited an increased open-circuit voltage (1.00 V vs 1.09 V), in consistent with the enhanced photoluminescence lifetime. The champion passivated device showed a ascendant power conversion efficiency (PCE) about 21.11% , with over 90% retention of the primal PCE in dry air after 1000 h aging with 20% ~ 30% humidity. A superior stability and an accelerated eletron/hole extraction ability were futher observed by time-resolved photoluminescence (TRPL) spectroscopy.
关键词： Charge-transport,High-performance,Spin coating,Crystallzation,Hysteresis,Ion migration
更新于2025-09-12 10:27:22
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Observation of Longitudinal Spin Seebeck Voltage in YIG Films Chemically Prepared by Co-Precipitation and Spin Coating
摘要： Longitudinal spin Seebeck effect (LSSE) of Y3Fe5O12 (YIG) thin films chemically prepared on a Si substrate with a SiO2 surface layer has been investigated with a particular focus on its dependence on the metal (Pt or W) for the capping layer used to carry out the measurements. The YIG films are prepared by a combination of co-precipitation, spin coating, and annealing processes. The structural characterization by X-ray diffraction proves that the films are polycrystalline in a garnet phase with an average crystallite size of ～34 nm. The microstructural analyses of the film surface by scanning electron microscopy and scanning probe microscopy show that the roughness Ra of the film is ～31 nm. The magnetic easy axis of the YIG films is in the direction parallel to the films. We have found that the polarity of the LSSE voltage VLSSE measured with a Pt capping layer apparently differs from that observed when a W capping layer is used. The value of VLSSE increases almost linearly with increasing temperature difference (cid:2)T independent of the choice of metal for the capping layer. The observed LSSE for the polycrystalline YIG films is one order of magnitude smaller than that reported for YIG and Bi:YIG single-crystal samples grown by metal–organic decomposition.
关键词： Co-precipitation,spin coating,garnet ferrite,spin Seebeck effect (SSE)
更新于2025-09-11 14:15:04
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Structurally simple OLEDs based on a new fluorinated poly(oxindolylidenearylene)
摘要： Organic light emitting diodes (OLEDs) based on a new polymer; are reported. This new polymer; Poly[(Benzo[c][1,2,5]thiadiazole-4,7-diylbis(9,9-dimethyl-9H-fluorene-7,2-diyl))-3,3-diyl(1-(3-(trifluoromethyl)phenyl)-2-oxindole)] (PF-2F), was used as emissive layer (EML), with a relatively simple architecture ITO/PEDOT:PSS/polymer/(LiF or PFN)/A, which is a modified version of our previously reported; PF-1: Poly[(Benzo[c][1,2,5]thiadiazole-4,7-diylbis(9,9-dimethyl-9H-fluorene-7,2-diyl(1-phenyl-2-oxindole)], applied in OLEDs and lasing devices. The main difference between these two polymers, is the trifluoromethyl (CF3) group addition to the PF-2F. CF3 leads to improved OLEDs electroluminescence and better EQEmax; due to enhanced mechanical properties, higher solubility and higher fluorescence quantum yield (FLQY). PF-1 and PF-2F polymers have an excellent FLQY: ~1. Polymer films (by spin coating) show low roughness value (~ 1-2 nm), just like polymers in OLEDs. OLEDs based on the modified polymer (with yellow-green electroluminescence (EL) emission) showed luminances of up to 1937 cd/m2, current efficiencies of up to 35 cd/A and maximum external quantum efficiency (EQEmax) of up to 2.6 %. Additionally, promising preliminary results on flexible OLEDs using PF-2F and PEDOT: PSS conductive (PH1000) (as anode) are reported.
关键词： Donor-Acceptor,Spin coating,Fluorinated polymer PF-2F,simple OLEDs
更新于2025-09-11 14:15:04
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Growth of Zinc Oxide Nanorods with the Thickness of Less than or Equal to 1? <i>μ</i> m through Zinc Acetate or Zinc Nitrate for Perovskite Solar Cell Applications
摘要： Arrays of zinc oxide (ZnO) nanorod (NR) were fabricated in a vertical axis direction through the two-step method of seed layer’s deposition and growth of the NR. The seed layer was applied by spin coating with a three-time repetition (n) and rotational speed (v) at 3000 rpm. After the seed layer had grown, ZnO NRs were grown with a growth solution made by combining one zinc source with one hydroxide source. There were two di?erent zinc sources, i.e., zinc acetate dehydrate and zinc nitrate hexahydrate and, for comparison, zinc acetate (ZA) and zinc nitrate (ZN) were each combined with the same hydroxide source, hexamethylene-tetramine (HMT). Later, the growth solutions were processed by the chemical bath deposition (CBD) method using a waterbath machine. The CBD method was started at room temperature until it reached the designated temperature at 85°C. At that point, the growth time was calculated from the zero-minute condition. It was found that ZnO NRs had already grown at a thickness of about 100 nm for both ZA and ZN sources. The growth time varied at 15, 60, 90, and 120 minutes after the zero-minute point. By using two separate and independent zinc sources while growing ZnO NRs at various growth periods, several ZnO NRs’ thicknesses were controlled. According to a paper by Lee et al., the lower thickness of ZnO NRs boosted the charge transfer properties of perovskite solar cells (PSCs) because the series resistance between ZnO/perovskite interfaces was lessened. Scanning electron microscopy (SEM) images were observed to analyze the morphological shape of the ZnO NRs. X-ray di?raction (XRD) pro?les were characterized to obtain the data for ZnO NR crystallinity. Full width at half maximum (FWHM) analysis was performed at the (002) ZnO peak to calculate the crystal size of the peak. From the results, the smallest crystallite sizes for ZnO NRs grown from ZA and ZN sources were 10.70 nm and 19.29 nm, respectively, which would be the most suitable condition for PSC application.
关键词： zinc oxide nanorods,perovskite solar cells,chemical bath deposition,spin coating,seed layer
更新于2025-09-11 14:15:04
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Correlation between the Morphology of ZnO Layers and the Electroluminescence of Quantum Dot Light-Emitting Diodes
摘要： The present work shows the e?ect of the ZnO layer morphology on inverted quantum dot light-emitting diodes (QLEDs) using di?erent spin-coating processes. In the inverted structure of ITO/ZnO/QDs/CBP/MoO3/Al, ZnO nanoparticles were used as the electron transport layer. The utilization of a two-step spin-coating process to deposit a ZnO layer on a patterned ITO glass substrate resulted in an increase in the surface roughness of the ZnO layer and a decrease in the luminance of the QLEDs. However, the current e?ciency of the device was enhanced by more than two-fold due to the reduced current density. Optimization of the ZnO spin-coating process can e?ciently improve the optical and electrical properties of QLEDs.
关键词： colloidal quantum dots,quantum dot light-emitting diodes,spin-coating process,ZnO
更新于2025-09-11 14:15:04
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Synthesis of uniform silver nanowires from AgCl seeds for transparent conductive films via spin-coating at variable spin-speed
摘要： Uniform silver nanowires (AgNWs) with high aspect ratio are significant to fabricate high-performance transparent conductive films (TCFs). In this work, AgNWs were synthesized through polyol method using AgCl as seeds. The growth mechanism of AgNWs upon AgCl particles was demonstrated, which provided a clear understanding of heterogeneous nucleation for synthesizing crystal. The amounts and the reaction time of AgCl were discussed to probe the effect on morphology of final AgNWs. Apart from that, the temperature was also tuned to provide appropriate thermal energy for synthesis of AgNWs. Uniform AgNWs with thin diameter about 52 nm and aspect ratio above 1000 were synthesized by optimizing the amounts, reaction time of AgCl and the temperature. These AgNWs were utilized to fabricate TCFs firstly through spin-coating at a variable speed. The resulting films coated at variable spin-speed largely improved the performance of films compared with those of films coated at constant spin-speed, exhibiting a low sheet resistance of 54Ω sq-1 and high transmittance of 92% at 550 nm with haze of 5.4%.
关键词： growth,AgCl,Silver nanowires,transparent conductive films,spin-coating
更新于2025-09-10 09:29:36