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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
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Influence of Annealing Atmosphere on Microstructure and Optical Properties of ZnO Thin Films
摘要： In this work, the ZnO films are deposited on conducting silicon chips by radio frequency magnetron sputtering. The as-deposited thin films are annealed at 800°C in a N2, O2 and CO+N2 atmosphere for 1h, respectively. The microstructure and electrical properties of the films are comprehensively investigated. XRD studies reveal that the ZnO films have a hexagonal wurtzite structure and they are highly oriented along (002) direction. The surface roughness of ZnO films decreased after annealing, which indicates better film quality. Room temperature PL spectrum is used to investigate the band gap and native defects existing in the films. Defects of thin films for different annealing conditions are analyzed in detail and the possible mechanism of the defects emission is discussed. We suggest that annealing atmosphere of CO+N2 is the most suitable annealing conditions for obtaining ZnO thin films with better crystal quality and good luminescence performance.
关键词： optical properties,ZnO thin films,annealing atmosphere
更新于2025-09-23 15:21:01
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Carrier Generation in p-Type Wide-Gap Oxide: SnNb <sub/>2</sub> O <sub/>6</sub> Foordite
摘要： Wide-gap oxides with their valence band maximum (VBM) composed of s orbitals are essential for realizing practical p-type transparent oxide semiconductors. We prepared a new p-type wide-gap oxide, SnNb2O6 foordite, with its VBM composed of Sn 5s orbitals. To discuss carrier generation, we prepared both p-type and n-type SnNb2O6 by controlling the annealing conditions. The carrier mobility and density were 3.8 × 10?1 cm2 V?1 s?1 and 3.7 × 1018 cm?3, respectively, for the p-type sample and 9.9 cm2 V?1 s?1 and 7.5 × 1015 cm?3, respectively, for the n-type sample. The crystal structure of SnNb2O6 foordite consists of two types of alternating layers, Sn and Nb2O6 octahedra, where three nonequivalent oxygen sites exist. Six oxygens in the chemical formula of SnNb2O6 are distributed at the three sites in pairs, where the oxygens in three nonequivalent sites were named O1?O3. Hole and electron carriers were considered to be generated by Sn4+-on-Nb5+ substitutional defects (SnNb??) and oxygen vacancies of O1 and O2 that are not bonded to Sn (VO1/O2′), respectively. Therefore, we concluded that it is essential to control SnNb?? and VO1/O2′ to control the semiconducting properties such as the carrier type and carrier density.
关键词： wide-gap oxides,carrier generation,SnNb2O6 foordite,annealing conditions,p-type transparent oxide semiconductors
更新于2025-09-23 15:21:01
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Controllable Multia??Step Preparation Method for Higha??Efficiency Perovskite Solar Cells with Low Annealing Temperature in Glove Box
摘要： Through a low-temperature process, a controlled two-step method in glove box is achieved, which avoids the need to transfer from glove box to air for annealing with the aid of moisture to assist crystallization in the traditional two-step method. Further utilizing recoating FA0.9MA0.1I solution to improve the formed perovskite, a high-efficiency perovskite solar cell is finally prepared through solid-liquid reaction.
关键词： low annealing temperature,perovskite solar cells,multi-step method,annealing-free
更新于2025-09-23 15:19:57
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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
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Inorganic and Pb-Free CsBi <sub/>3</sub> I <sub/>10</sub> Thin Film for Photovoltaic Applications
摘要： Computational, thin-film deposition and characterization approaches have been used to investigate the all inorganic lead-free CsBi3I10 as a candidate thin-film photovoltaic absorber. In this paper, CsBi3I10 was firstly predicted with a layer crystal structure of stable hexagonal phase like Cs3Bi2I9 and then prepared by one-step coating also showing the high purity hexagonal phase and crystallinity, very consistent with the theoretical calculation. After solvent annealing, a high absorption coefficient of approximately 105 cm?1 in visible light and a suitable optical bandgap of 1.78 eV were obtained for CsBi3I10 thin film. The solar cell based on CsBi3I10 perovskite thin film exhibited high power conversion efficiency of 1.05%, good reproducibility, hysteresis-freeness, and long-term stability. These results indicate that the performance of all-inorganic Pb-free perovskite solar cells can be further improved.
关键词： thin-film photovoltaic absorber,perovskite solar cells,CsBi3I10,solvent annealing,lead-free
更新于2025-09-23 15:19:57
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Nitrogen doping of TiO2 and annealing treatment of photoanode for enhanced solar cell performance
摘要： Mild doping of nitrogen (N) in TiO2 followed by an optimized aerial annealing treatment of CdS quantum dot (QD) sensitized photoanode resulted in ef?cient electron transfer and low recombination rates for the corresponding quantum dot solar cell (QDSC). Nitrogen doping passivates the surface defects in TiO2, reduces the density of recombination centers, and promotes electron injection into the current collector. N-doping also modi?es the electronic band structure of TiO2 and reduces the band gap from 3.17 to 2.91 eV. Therefore in the QDSC with the N-TiO2/CdS photoanode, both N-TiO2 and CdS, undergo charge separation upon illumination thereby producing a higher photocurrent compared to the undoped-TiO2/CdS based QDSC. N-doping also increased the redox activity of TiO2, allowing facile ion and electron transport across its cross-section which is advantageous for solar cell performance. Optimal annealing temperature of 150 (cid:1)C for the N-TiO2/CdS or TiO2/CdS photoanode restricted the back electron movement effectively, and imparted a signi?cantly enhanced power conversion ef?ciency (PCE) to the N-TiO2/CdS@150 (cid:1)C/polysul?de gel/C-fabric- solar cell, greater by 55% compared to its unannealed counterpart. Lowered average excited electron lifetime, increased-incident photon-to-current conversion ef?ciency, recombination resistance and photovoltage decay response time, con?rm the ability of the annealed photoanodes to undergo enhanced charge separation contrasting with the unannealed photoanode. This ?rst time study relies on two simple approaches of nitrogen doping and annealing treatment to achieve considerably improved photovoltaic parameters, and opens up realistic possibilities for commercialization of QDSCs.
关键词： Annealing treatment,Recombination,Charge transfer,N-doping,Solar cell
更新于2025-09-23 15:19:57
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Effects of post bonding annealing on GaAs//Si bonding interfaces and its application for sacrificial-layer-etching based multijunction solar cells
摘要： By using the sacrificial layer (SL) etching, GaAs substrates are separated from III–V epi substrate//Si substrate junctions that are made by surface activated bonding (SAB) technologies. The post-bonding low-temperature (300-?C) annealing plays an essential role in achieving a promising (～90%) bonding yield. The effects of the post-bonding annealing are investigated by hard X-ray photoemission spectroscopy and current–voltage measurements of GaAs//Si bonding interfaces. It is found that the concentration of oxygen atoms at interfaces is reduced and the resistance decreases to 1.6–2.1 m??cm2 by the low-temperature annealing. Aluminum fluoride complexes are not observed by X-ray photoelectron spectroscopy on the exposed surfaces of separated GaAs substrates. The roughness average of the surfaces is ≈0.25–0.30 nm. The characteristics of double junction cells fabricated on the GaAs//Si junctions prepared by the SL etching are almost the same as those of cells fabricated by dissolving GaAs substrates after bonding. These results indicate that multijunction cells could be fabricated in a process sequence compatible with reuse of GaAs substrates by combining the SL etching and SAB.
关键词： Sacrificial layer etching,GaAs//Si double junction cells,Surface activated bonding,Low temperature annealing,Epitaxial lift-off
更新于2025-09-23 15:19:57
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Synthesis and Characterization of Wide-Bandgap Conjugated Polymers Consisting of Same Electron Donor and Different Electron-Deficient Units and Their Application for Nonfullerene Polymer Solar Cells
摘要： Substantial development has been made in nonfullerene small molecule acceptors (NFSMAs) that has resulted in a significant increase in the power conversion efficiency (PCE) of nonfullerene-based polymer solar cells (PSCs). In order to achieve better compatibility with narrow-bandgap nonfullerene small molecule acceptors, it is important to design the conjugated polymers with a wide bandgap that has suitable molecular orbital energy levels. Here two donor–acceptor (D–A)-conjugated copolymers are designed and synthesized with the same thienyl-substituted benzodithiophene and different acceptors, i.e., poly{(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)-alt-(1,3-bis(2-octyldodecyl)-1,3-dihydro-2H-dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2-d]imidazol-2-one-5,8-diyl)} (DTBIA, P1) and poly{(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)-alt-(2-(5-(3-octyltridecyl)thiophen-2-yl)dithieno[3′,2′:3,4;2″,3″:5,6]benzo[1,2-d]thiazole-5,8-diyl)} (TDTBTA, P2) (and their optical and electrochemical properties are investigated). Both P1 and P2 exhibit similar deeper highest occupied molecular orbital energy level and different lowest unoccupied molecular orbital energy level. Both the copolymers have complementary absorption with a well-known nonfullerene acceptor ITIC-F. When blended with a narrow-bandgap acceptor ITIC-F, the PSCs based on P1 show a power conversion efficiency of 11.18% with a large open-circuit voltage of 0.96 V, a Jsc of 16.89 mA cm?2, and a fill factor (FF) of 0.69, which is larger than that for P2 counterpart (PCE = 9.32%, Jsc = 15.88 mA cm?2, Voc = 0.91 V, and FF = 0.645). Moreover, the energy losses for the PSCs based on P1 and P2 are 0.54 and 0.59 eV, respectively. Compared to P2, the P1-based PSCs show high values of incident photon to current conversion efficiency (IPCE) in the shorter-wavelength region (absorption of donor copolymer), more balanced hole and electron mobilities, and favorable phase separation with compact π–π stacking distance.
关键词： solvent vapor annealing,polymer solar cells,nonfullerene acceptors,wide-bandgap polymers
更新于2025-09-23 15:19:57
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Highly Rectifying Heterojunctions Formed by Annealed ZnO Nanorods on GaN Substrates
摘要： We study the effect of thermal annealing on the electrical properties of the nanoscale p-n heterojunctions based on single n-type ZnO nanorods on p-type GaN substrates. The ZnO nanorods are prepared by chemical bath deposition on both plain GaN substrates and on the substrates locally patterned by focused ion beam lithography. Electrical properties of single nanorod heterojunctions are measured with a nanoprobe in the vacuum chamber of a scanning electron microscope. The focused ion beam lithography provides a uniform nucleation of ZnO, which results in a uniform growth of ZnO nanorods. The specific configuration of the interface between the ZnO nanorods and GaN substrate created by the focused ion beam suppresses the surface leakage current and improves the current-voltage characteristics. Further improvement of the electrical characteristics is achieved by annealing of the structures in nitrogen, which limits the defect-mediated leakage current and increases the carrier injection efficiency.
关键词： chemical bath deposition,nanoscale heterojunctions,ZnO nanorods,nanoprobe in the scanning electron microscope,current-voltage characteristics,annealing,focused ion beam patterning
更新于2025-09-23 15:19:57