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Solution-processable PEDOT:PSS:?±-In2Se3 with enhanced conductivity as a hole transport layer for high-performance polymer solar cells
摘要： Two-dimensional (2D) nanosheets have attracted enormous attention in photovoltaic devices owing to their outstanding photoelectric properties in recent years. Herein, 2D α-In2Se3 nanosheets with higher conductivity and suitable work function are synthesized by liquid phase exfoliation method. To ameliorate the low conductivity of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) (2.21×10-3 S cm-1), α-In2Se3 nanosheets are directly added into PEDOT:PSS to obtain PEDOT:PSS:α-In2Se3 composite film. The composite film exhibits excellent optical transmittance, suitable work function, and enhanced conductivity (1.54×10-2 S cm-1). To profoundly investigate the mechanism of conductivity improvement, XPS, Raman, EPR and AFM measurements are conducted. The results show that the synergistic effect of 2D α-In2Se3 nanosheets and isopropanol/deionized water cosolvent screens the Coulombic attraction among PEDOT and PSS. The screening effect results in the partial removal of PSS and the benzoid-quinoid transition of PEDOT. In addition, α-In2Se3 nanosheets may serve as physical linkers for PEDOT chains. Both effects are beneficial to increase interfacial contact area between PEDOT chains and form a larger conductive network of PEDOT, leading to an enhanced conductivity. The composite film is first employed as a hole transport layer (HTL) in polymer solar cells (PSCs). The power conversion efficiency (PCE) of PBDB-T:ITIC-based device with composite HTL is 10% higher than that of unmodified PBDB-T:ITIC-based device, and the maximum PCE of 15.89% is achieved in PM6:Y6 system. More interestingly, the stability of devices with composite HTL is improved owing to the partial removal of PSS. Thus the PEDOT:PSS:α-In2Se3 composite can be an application prospect HTL material in PSCs.
关键词： polymer solar cells,hole transport layer,α-In2Se3,PEDOT:PSS,stability
更新于2025-09-23 15:21:01
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Hole-doped 2D InSe for spintronic applications
摘要： Using first-principles calculations based on density functional theory, we study the magnetic and electronic properties of hole-doped two-dimensional InSe. Our simulations reveal that although 2D InSe is intrinsically non-magnetic, a stable ferromagnetic phase appears for a wide range of hole densities. Interestingly, hole doping not only induces spontaneous magnetization but also half-metallicity, and hole-doped InSe, presenting one conducting and one insulating spin channel, could be highly promising for next generation spintronic nanodevices. The possibility to induce hole doping and a subsequent ferromagnetic order by intrinsic and extrinsic defects was also investigated. We found that In vacancy creates spin-polarized states close to the valence band and leads to a p-type behavior. Similar to In vacancies, group-V atoms replacing Se atoms lead to a p-type behavior, potentially stabilizing a ferromagnetic order in 2D InSe.
关键词： ferromagnetism,InSe,half-metallicity,hole-doping,defects
更新于2025-09-23 15:21:01
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Design of hole transport type host for stable operation in blue organic light-emitting diodes
摘要： Molecular design of the hole transport type host for mixed host was investigated to improve the lifetime of the phosphorescent organic light-emitting diodes. A negative polaron stabilizing hole transport type host design was employed and the effect of the negative polaron stabilizing unit was investigated. Dibenzofuran or benzonitrile was introduced as the negative polaron stabilizing unit in the bicarbazole backbone structure of the hole transport type host. Two host materials were synthesized and the comparison of them proposed that the negative polaron stabilizing unit is a key to the lifetime of the phosphorescent organic light-emitting diodes. The dibenzofuran and benzonitrile embedded bicarbazole hosts performed better than the mCBP host. The dibenzofuran and benzonitrile modified bicarbazole hosts demonstrated high external quantum efficiency of 18.6 and 19.1%, respectively and lifetime extension by 30% compared with the conventional host without the negative polaron stabilizing unit.
关键词： Negative polaron,Lifetime,Mixed host,Hole type host
更新于2025-09-23 15:21:01
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Perovskite solar cells based on the synergy between carbon electrodes and polyethylene glycol additive with excellent stability
摘要： The quality of the photoactive layer gravely affects the characteristics and stabilities of photovoltaic device. Here, by introducing polyethylene glycol (PEG) into the methylammonium lead trihalide (MAPbI3) precursor solution, we fabricate high-quality MAPbI3 perovskite film with high coverage and large grain size. By adjusting the PEG concentration into the perovskite film, the hole-conductor-free mesoporous perovskite solar cell with carbon electrode exhibits a boosted power conversion efficiency of 11.62%, which originates primarily from the enhancements of light absorption and acceleration of carriers transfer. Meanwhile, hygroscopic PEG protects the perovskite film from moisture, which leads to the perovskite film and corresponding device exhibit superior stability. This work confirms a high-efficiency and feasible strategy using polymer materials to enhance the performance in power conversion efficiency and stability of perovskite solar cells.
关键词： Carbon counter electrode,Hygroscopic polyethylene glycol additive,Perovskite solar cells,High stability,Hole-conductor-free
更新于2025-09-23 15:21:01
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The Performance Improvement of Using Hole Transport Layer with Lithium and Cobalt for Inverted Planar Perovskite Solar Cell
摘要： With the continuous development of solar cells, the perovskite solar cells (PSCs), whose hole transport layer plays a vital part in collection of photogenerated carriers, have been studied by many researchers. Interface transport layers are important for efficiency and stability enhancement. In this paper, we demonstrated that lithium (Li) and cobalt (Co) codoped in the novel inorganic hole transport layer named NiOx, which were deposited onto ITO substrates via solution methods at room temperature, can greatly enhance performance based on inverted structures of planar heterojunction PSCs. Compared to the pristine NiOx films, doping a certain amount of Li and Co can increase optical transparency, work function, electrical conductivity and hole mobility of NiOx film. Furthermore, experimental results certified that coating CH3NH3PbIxCl3?x perovskite films on Li and Co- NiOx electrode interlayer film can improve chemical stability and absorbing ability of sunlight than the pristine NiOx. Consequently, the power conversion efficiency (PCE) of PSCs has a great improvement from 14.1% to 18.7% when codoped with 10% Li and 5% Co in NiOx. Moreover, the short-circuit current density (Jsc) was increased from 20.09 mA/cm2 to 21.7 mA/cm2 and the fill factor (FF) was enhanced from 0.70 to 0.75 for the PSCs. The experiment results demonstrated that the Li and Co codoped NiOx can be a effective dopant to improve the performance of the PSCs.
关键词： codoping,nickle oxide,hole transport layer,perovskite solar cells,performance
更新于2025-09-23 15:21:01
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Effect of the corona treatment on the microstructure of PVDF probed by electrochemical impedance spectroscopy
摘要： The microstructure of Polyvinylidene Fluoride (PVDF) membrane treated by corona was investigated in this study. The crystalline structure of PVDF membrane was con?rmed by x-ray diffraction (XRD), and the hole structure was evaluated by electrochemical impedance spectroscopy (EIS). It was found that the β phase appears in XRD pattern for treated PVDF, implying the polarization during corona treatment. The variation of membrane resistance suggested that the hole structure of PVDF became more porous with increasing treated time from 0 h to 2 h ?rstly, then became denser with treated time from 2 h to 4 h, and ?nally cracked at the treated time longer than 4 h. All the results indicated that corona treatment would induce the change of the bulk structure of PVDF membrane.
关键词： polyvinylidene ?uoride,corona treatment,electrochemical impedance spectroscopy,hole structure
更新于2025-09-23 15:21:01
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One Dimensional CdS Nanotube vs CdS Bulk Structure for Photocatalytic Water Splitting: Role of Dimensionality
摘要： Using the state-of-the-art density functional theoretical calculations, we have modelled a facetted CdS nanotube (NT) catalyst for photocatalytic water splitting. The overall photocatalytic activity of the CdS photocatalyst has been predicted based on the electronic structures, band edge alignment, and overpotential study. For comparisons, we have also investigated the water spilitting process over the CdS bulk structure. The band edge alignment along with oxygen evolution reaction/hydrogen evolution reaction (OER/HER) mechanism studies help us to find out the effective overpotential for the overall water splitting on these surfaces. Our study shows that CdS NT has highly stabilized valence band edge compared to that in the CdS bulk due to strong p-d mixing. Such highly stabilized valence band edge is important for the hole-transfer process and reduces the risk of electron-hole recombination. Such nanotube requires less overpotential for water oxidation reaction than the periodic CdS. All these suggest that the efficiency of water oxidation/reduction process further improves in CdS as we reduce its dimensionality. More importantly, we report here that there are two factors, which makes CdS nanotube as a better photocatalyst material compared to its bulk counterpart. Furthermore, the stabilized valence band edge is good for their photostability too as bulk CdS suffers from photostability.
关键词： photocatalysis,HER,CdS nanotube,OER,electron-hole recombination
更新于2025-09-23 15:21:01
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A physical model of the broad-band continuum of AGN and its implications for the UV/X relation and optical variability
摘要： We develop a new spectral model for the broad-band spectral energy distribution (SED) of active galactic nuclei (AGN). This includes an outer standard disc, an inner warm Comptonizing region to produce the soft X-ray excess and a hot corona. We tie these together energetically by assuming Novikov–Thorne emissivity, and use this to de?ne a size scale for the hard X-ray corona as equal to the radius where the remaining accretion energy down to the black hole can power the observed X-ray emission. We test this on three AGN with well-de?ned SEDs as well as on larger samples to show that the average hard X-ray luminosity is always approximately a few per cent of the Eddington luminosity across a large range of Eddington ratio. As a consequence, the radial size scale required for gravity to power the X-ray corona has to decrease with increasing Eddington fraction. For the ?rst time, we hardwire this into the spectral models, and set the hard X-ray spectral index self-consistently from the ratio of the hard X-ray luminosity to intercepted seed photon luminosity from the disc. This matches the observed correlation of steeper spectral index with increasing Eddington ratio, as well as reproducing the observed tight UV/X relation of quasars. We also include the reprocessed emission produced by the hot inner ?ow illuminating the warm Comptonization and standard disc regions and show that this predicts a decreasing amount of optical variability with increasing Eddington ratio as observed, though additional processes may also be required to explain the observed optical variability.
关键词： galaxies: Seyfert,accretion,black hole physics,accretion discs
更新于2025-09-23 15:21:01
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Three-particle electron-hole complexes in two-dimensional electron systems
摘要： Three-particle complexes consisting of two holes in the completely filled zero-electron Landau level and an excited electron in the unoccupied first Landau level are investigated in a quantum Hall insulator. The distinctive features of these three-particle complexes are an electron-hole mass symmetry and the small energy gap of the quantum Hall insulator itself. Theoretical calculations of the trion energy spectrum in a quantizing magnetic field predict that, besides the ground state, trions feature a hierarchy of excited bound states. In agreement with the theoretical simulations, we observe new photoluminescence lines related to the excited trion states. A relatively small energy gap allows the binding of three-particle complexes with magnetoplasma oscillations and the formation of plasmarons. The plasmaron properties are investigated experimentally.
关键词： photoluminescence,plasmarons,electron-hole mass symmetry,quantum Hall insulator,trion energy spectrum,three-particle complexes
更新于2025-09-23 15:21:01
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Effects of Parasitic Region in SiC Bipolar Junction Transistors on Forced Current Gain
摘要： Effects of a parasitic region in SiC BJTs on conductivity modulation and a forced current gain (????) were investigated by using TCAD simulation with various device structures. By introducing an Al+-implanted region below the base parasitic region, ???? can be improved because the implanted region can reduce the base spreading resistance, leading to alleviation of debiasing effect. ???? in devices with various parasitic areas, whose base spreading resistances were reduced by the Al+-implantation, were compared. We found that ???? can be enhanced by expanding the parasitic area if the base spreading resistance is sufficiently reduced. The higher ???? is attributed to an expanded conductivity-modulated region. The collector current spreading in the collector layer and hole injection from the parasitic region as well as from the intrinsic region can play a role to evoke conductivity modulation. Thus, the larger parasitic region can expand the conductivity-modulated region, which results in expansion of an active area and the enhancement of ????, though a higher base voltage is required.
关键词： forced current gain,conductivity modulation,parasitic region,hole injection,SiC BJT,base spreading resistance
更新于2025-09-23 15:21:01