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oe1(光电查) - 科学论文

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  • Annealing CsPbX <sub/>3</sub> (X = Cl and Br) Perovskite Nanocrystals at High Reaction Temperatures: Phase Change and Its Prevention

    摘要： Annealing perovskite nanocrystals at high reaction temperature changes their crystal phase, shape, and optical properties. Carrying out reactions between 180 and 250 °C, the impact of thermal annealing for CsPbCl3 and CsPbBr3 nanocrystals in a reaction ?ask was investigated here. At higher temperature, a phase change was observed instantly, which could not be trapped even with ice-bath cooling. Interestingly, using a calculated amount of preformed alkylammonium halides as dual passivating agents, the nanocrystals of both CsPbCl3 and CsPbBr3 could even be stabilized for hours of annealing at 250 °C. CsPbCl3, which was reported to be a poor emissive nanocrystal in comparison to CsPbBr3, could sustain even more than 5 h of annealing at 250 °C and recorded ～51% absolutely quantum yield. Details of the interface chemistry and the role of the used dual passivating agent for providing thermal stability are studied and reported in this Letter.

    关键词： thermal annealing,quantum yield,phase change,dual passivating agents,perovskite nanocrystals

    更新于2025-09-23 15:21:01

  • Firing voltage reduction in thermally annealed Gea??Asa??Te thin film with ovonic threshold switching

    摘要： Recently, chalcogenide materials have exhibited ovonic threshold switching characteristics, improving their suitability as selector devices to effectively depress the sneak current in the cross-point array (CPA) structures. However, chalcogenides must be subjected to a firing process before they can exhibit the threshold switching behavior. The firing process causes operation problems with respect to the memory operation process in the case of the CPA structure. Although the firing process is expected to be related to Joule heating with a high electric current, the physical nature of the changes during the firing process remains unclear. In this study, selector devices are fabricated by sandwiching amorphous Ge–As–Te thin films between the TiN and W layers. Furthermore, the authors examine the microstructure of the Ge–As–Te thin films before and after the electric firing process using transmittance electron microscopy (TEM, JEOL JEM-F200). The TEM analysis of the pristine Ge–As–Te thin films denotes the uniform contrast of the image, which implies the uniform chemical composition of the film. However, the Ge–As–Te thin films exhibit nonuniform contrast due to the effects of Joule heating after the electric firing process. The Ge–As–Te thin films were thermally annealed at 150 and 250 °C for 1 min via the rapid thermal annealing process to verify the effects of thermal treatment on the firing process in chalcogenide thin films. The effect of thermal annealing on the threshold switching behavior was also investigated by studying the compositional stability. Their results showed that the thermal annealing process caused the uniform compositions on the pristine Ge–As–Te films to be fluctuated with decreasing firing voltage for threshold switching.

    关键词： Ge–As–Te thin films,chalcogenide materials,thermal annealing,ovonic threshold switching,firing process

    更新于2025-09-23 15:21:01

  • Effect of DI Water Content on the Growth of Anatase TiO<sub>2</sub> Nanotubes Synthesized by Anodization Process

    摘要： Vertically aligned anatase TiO2 nanotubes (NTs) were fabricated by anodization of a pure Ti foil in ethylene glycol solutions containing different concentrations of deionized (DI) water. The morphology, elemental composition, and crystallization of TiO2 nanostructures were analyzed by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray spectroscopy (XPS), respectively. The diameter and length of TiO2 NTs were controlled by varying concentrations of DI water. Furthermore, we found that TiO2 NTs in DI water 12 wt. % was suitable for further applications in UV photodetector due to it has a high volume to surface area ratio and long tube. TiO2 NTs have a high potential in various applications such as UV photodetectors, gas sensor, dye sensitized solar cells, and photocatalysts.

    关键词： Anatase TiO2,Anodization,Thermal annealing,Titanium dioxide,Nanotubes

    更新于2025-09-23 15:21:01

  • Morphology Control of Doped Spiroa??MeOTAD Films for Air Stable Perovskite Solar Cells

    摘要： Doped 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-MeOTAD), which acts as a hole-transporting layer (HTL), endows perovskite solar cells (PSCs) with excellent performance. However, the intrinsically hygroscopic nature of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) dopants also aggravates the moisture instability of PSCs. In this work, the origins of the moisture instability of spiro-MeOTAD HTLs are explored and strategies to enhance moisture resistance are proposed. After 780 h of aging in air, 52% of the initial power conversion efficiency (PCE) can be sustained by prolonging the mixing time of the precursor solution of spiro-MeOTAD to reduce accumulated LiTFSI. In contrast, only 7% of the initial PCE remains if the precursor solution is mixed briefly. By thermally annealing an HTL to evaporate residual tBP in spiro-MeOTAD, pinholes are completely eliminated and 65% of the initial PCE remains after the same aging time. In this study, the significance of the initial morphology of spiro-MeOTAD HTLs on device stability is analyzed and strategies based on physical morphology for controlling PSC moisture instability induced by HTL dopants are developed.

    关键词： moisture stability,perovskite solar cells,thermal annealing,spiro-MeOTAD

    更新于2025-09-23 15:19:57

  • 1200nma??Band InAs/GaAs Quantum Dot Intermixing by Dry Etching and Ion Implantation

    摘要： In this paper, the quantum dot intermixing (QDI) technique previously developed for 1550nm-band InAs/InAlGaAs quantum dot (QD) was applied to 1200nm-band InAs/GaAs QD. Three methods of defect introduction for triggering the QDI were employed such as ICP-RIE (Ar+) and ion implantation (Ar+ and B+). As a result, about 80nm PL peak wavelength shift was obtained for ICP-RIE when annealing was performed at 575 °C, after etching down to 450 nm to the QD layer. On the other hand, about 110nm PL peak wavelength shift was obtained for B+ ion implantation at an acceleration energy of 120 keV and a dose of 1.0×1014 /cm2 and subsequent annealing. Cross sectional image analyses by Scanning Transmission Electron Microscope (STEM) and Energy-Dispersive X-ray Spectroscopy (EDX) clarified the modification of InAs QD structures by the QDI process.

    关键词： intermixing,InAs/GaAs quantum dot,ICP-RIE,rapid thermal annealing,ion implantation

    更新于2025-09-23 15:19:57

  • Toward reliable high performing organic solar cells: Molecules, processing, and monitoring

    摘要： A steady surge in device efficiencies of organic solar cells (OSCs) along with improvement in associated features, such as stability and facile processing methods, is expected to provide a realistic, feasible commercial option. The introduction of high performing donor and acceptor molecules along with tailored buffer layers has provided the impetus for the resurgence of this field. Further options of ternary and tandem architectures of these OSC systems should push this technology to competitive levels. A major hurdle, which is expected when these devices are evaluated for long-term performance in all weather conditions, is the level of degradation. We examine and address these stability-limiting factors in this perspective article. Modifications in microstructure/morphology and interfaces with time and energy levels defining the molecules form some of the critical intrinsic degradation pathways. Various strategies that have been used to limit the associated pathways of degradation of the active layer will be discussed. One such strategy is electric field-assisted thermal annealing treatment, which concomitantly also brings in a favorable vertical phase segregated active layer morphology. We also emphasize the utility of photocurrent noise measurements to monitor the level of degradation and possibly forecast the trajectory of long-term performance of OSCs.

    关键词： processing methods,photocurrent noise measurements,electric field-assisted thermal annealing,device efficiencies,degradation,donor and acceptor molecules,organic solar cells,stability,ternary and tandem architectures

    更新于2025-09-23 15:19:57

  • A Nontoxic Bifunctional (Anti)Solvent as Digestivea??Ripening Agent for Higha??Performance Perovskite Solar Cells

    摘要： The preparation of high-quality perovskite films is important for achieving high-performance perovskite solar cells (PSCs). The effective balance between solvent and antisolvent is an essential factor for regulating high-quality perovskite film during the spin-coating and thermal-annealing steps. In this work, a greener, nonhalogenated, nontoxic bifunctional (anti)solvent, methyl benzoate (MB), is developed not only as an antisolvent to rapidly generate crystal seeds at the perovskite spin-coating step, but also as a digestive-ripening solvent for the perovskite precursors, which can prevent the loss of organic components during the thermal-annealing stage and effectively suppress the formation of miscellaneous lead halide phases. As a result, this novel bifunctional (anti)solvent is employed in planar n–i–p PSCs for engineering high-quality perovskite layers and thus achieving a power conversion efficiency up to 22.37% with negligible hysteresis and >1300 h stability. Moreover, due to the high boiling point and low-volatility characteristic of MB, high-performance PSCs are achieved reproducibly at different operating temperatures (22–34 °C). Therefore, this developed bifunctional solvent system can provide a promising platform toward globally upscaling and commercializing PSCs in all seasons and regions.

    关键词： digestive ripening,antisolvents,methyl benzoate,perovskites,thermal annealing,solvents

    更新于2025-09-23 15:19:57

  • Boron-doped graphene synthesis by pulsed laser co-deposition of carbon and boron

    摘要： Incorporating dopants, such as boron, in graphene, is crucial for many applications in electrochemistry, sensors, photovoltaics, and catalysis. Many routes have been investigated for the preparation of B-doped graphene (BG) films, including chemical processes. A different way to obtain boron-doped layers to better control the concentration of boron in the doped graphene film, is pulsed laser co-ablation of C and B solid sources followed by rapid thermal heating of the B-doped carbon film deposited on a metal catalyst. Amorphous a-C:B films, containing 2%at. boron, are synthetized by pulse laser deposition onto a nickel film catalyst. Rapid thermal annealing at 1100°C leads to the formation of boron-doped graphene films, characterized by Raman, XPS, FEG-SEM, HRTEM and AFM. The results confirm the production of 1-4 layer boron doped graphene films, with a similar 2 at.% boron concentration to that of the a-C:B used as the graphene solid precursor. Boron doping does not modify the nano-architecture of graphene, but increases the concentration of defects in the films. Our results pave a new way for boron doped graphene synthesis using laser processing in a controlled and reproducible way, in particular to achieve designed electrical and chemical properties in various electronic and electrochemical applications.

    关键词： Raman spectroscopy,Boron-doped graphene,Pulsed laser deposition,Rapid thermal annealing,HRTEM,XPS,AFM

    更新于2025-09-23 15:19:57

  • Maximize CdTe solar cell performance through copper activation engineering

    摘要： The incorporation of copper (Cu) is one of the critical processes for fabricating high-efficiency CdTe thin-film solar cells. However, due to its high mobility in CdTe, the distribution and concentration of Cu must be carefully engineered to reduce the compensative donor-like interstitial defects in CdTe bulk and the recombination centers at the buffer layer/CdTe interface to maximize device performances. Here, a cuprous chloride (CuCl) solution treatment and a rapid thermal annealing (RTA) process are used to control the concentration and distribution of Cu in CdTe absorbers, enabling a champion CdTe thin-film solar cell with a power conversion efficiency of 17.5% without selenium incorporation. The results demonstrate that the use of a CuCl solution can substantially reduce the amount of Cu needed in CdTe and the RTA process is a viable approach to engineer the Cu distribution in CdTe solar cells.

    关键词： Power conversion efficiency,Rapid thermal annealing,Cuprous chloride,CdTe solar cells,Copper activation

    更新于2025-09-23 15:19:57

  • Controlling In‐Ga‐Zn‐O Thin‐Film Resistance by Vacuum Rapid Thermal Annealing and Application to Transparent Electrode

    摘要： This study reveals that an amorphous indium gallium zinc oxide film shows a large resistance change under vacuum rapid thermal annealing, whereas a zinc tin oxide film shows little resistance change under the same treatment. Based on these findings, the applicability of amorphous indium gallium zinc oxide thin films to a transparent source/drain electrode in zinc tin oxide thin-film transistors is investigated. The optical transmittance of the amorphous indium gallium zinc oxide and amorphous zinc tin oxide films in the visible region is greater than 85%. Furthermore, a zinc tin oxide thin-film transistor with an amorphous indium gallium zinc oxide source/drain electrode exhibits superior operation characteristics than devices with indium tin oxide source/drain electrodes, such as a lower threshold swing (from 369.96 to 315.45 mV dec?1), higher mobility (from 28.47 to 36.187 cm2 V?1 s?1), and higher on/off current ratio (from 1.25 × 107 to 3.56 × 107). In addition, in positive and negative bias temperature stress tests, the zinc tin oxide thin-film transistor with an amorphous indium gallium zinc oxide source/drain electrode shows almost equal stability compared to the zinc tin oxide thin-film transistor with an indium tin oxide source/drain electrode.

    关键词： Zn-Sn-O (ZTO),In-Ga-Zn-O (IGZO) S/D electrode,thin-film transistors (TFT),vacuum rapid thermal annealing

    更新于2025-09-23 15:19:57