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Ba-induced phase segregation and band gap reduction in mixed-halide inorganic perovskite solar cells
摘要： All-inorganic metal halide perovskites are showing promising development towards efficient long-term stable materials and solar cells. Element doping, especially on the lead site, has been proved to be a useful strategy to obtain the desired film quality and material phase for high efficient and stable inorganic perovskite solar cells. Here we demonstrate a function by adding barium in CsPbI2Br. We find that barium is not incorporated into the perovskite lattice but induces phase segregation, resulting in a change in the iodide/bromide ratio compared with the precursor stoichiometry and consequently a reduction in the band gap energy of the perovskite phase. The device with 20 mol% barium shows a high power conversion efficiency of 14.0% and a great suppression of non-radiative recombination within the inorganic perovskite, yielding a high open-circuit voltage of 1.33 V and an external quantum efficiency of electroluminescence of 10?4.
关键词： inorganic perovskite solar cells,barium doping,non-radiative recombination,band gap reduction,phase segregation
更新于2025-09-19 17:13:59
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Controlled synthesis of SnSxSe2?x nanoplate alloys via synergetic control of reactant activity and surface defect passivation control with surfactant and co-surfactant mixture
摘要： Two-dimensional (2D) metal dichalcogenide nanomaterials have been receiving enormous research interest for electronic, optoelectronic, and catalytic applications. However, the facile tunability of alloying and doping, as well as the successful formation of ideal defect-free nanoplate morphology have been hardly achieved for 2D nanomaterials. Herein, we successfully synthesized a series of 2D solid-solution SnSxSe2(cid:1)x particles of 0.20–2.00 μm width and 30–68 nm thickness with morphological defect-free nanoplate via a solvothermal reaction. With controlled reactivities of elemental chalcogen precursors, a co-surfactant hexylamine together with a structure-directing agent polyvinylpyrrolidone was found to be essential for realizing ideal defect-free nanoplate morphology of SnSxSe2(cid:1)x particles without either cabbage-like or twinned structure. The successful synthesis of morphologically defect-free SnSxSe2(cid:1)x nanoplates with rationally controlled energy band gaps ranging from 1.36 eV for SnSe2 to 1.96 eV for SnS2 could provide promising materials for electronics, optoelectronics, and electrocatalytic applications.
关键词： 2D nanomaterials,Nanoplate,SnSe2,SnS2,Band gap,SnSxSe2(cid:1)x
更新于2025-09-19 17:13:59
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Structural and Electro-Optical Properties of Electrospun Cu-Doped ZnO Thin Films
摘要： Pure and Cu-doped ZnO thin films (TFs) were synthesized on glass substrates via the electrospinning method, and the effects of Cu concentration on electro-optical and structural properties were investigated. The nanofibers (NFs) changed to cross-linked nanoparticles (NPs) via calcination at 400 °C. XRD results indicate that Cu2+ was successfully incorporated into the ZnO host to form a hexagonal wurtzite structure. The crystallography of Cu-doped ZnO (CZO) was systematically investigated; it was found that both c/a ratio and compressive lattice strain increased. The photoluminescence (PL) behavior of CZO TFs revealed that the excitonic and redshifted UV emissions were manipulated by Zni, Oi, VZn, OZn and VO defect states. Optical absorption measurements showed excellent transmission percentages (above 87%) in the visible light range. The optical band gap of ZnO TFs decreased from 3.3 eV to 3.2 eV after incorporation of Cu. The results of this study show that electrospun CZO TFs has immense potential for use in electro-optical applications.
关键词： Crystallography,Electrospinning,Transmittance,Band gap,Photoluminescence,Copper
更新于2025-09-19 17:13:59
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Design of high-performance double quantum well vertical cavity transistor lasers with GRIN base region
摘要： Different confinement structures are analyzed to achieve higher optoelectronic performances for double quantum well vertical cavity transistor laser with graded index separate confinement heterostructure. Adding the drift component to the diffusion term of the current density and solving new sets of equations, modified electro-optic performances of the device is obtained. Band-gap engineering of the original structure predicts simultaneous improvements in both current gain (more than two times) and ?3 dB optical bandwidth (by 1.5 GHz). Other less critical, yet important, performance metrics including optical output power and threshold current (up to 20%) are enhanced due to applying graded layers of AlξGa1-ξAs in the base region.
关键词： Vertical cavity transistor laser,GRIN base region,Optoelectronic performance,Double quantum well,Band-gap engineering
更新于2025-09-19 17:13:59
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Single-Walled boron nitride nanotubes interaction with nickel, titanium, palladium, and gold metal atoms- A first-principles study
摘要： Ab initio calculations based on density functional theory was carried out to study the electronic properties of (3,3), (4,2), (5,2) and (6,0) boron nitride nanotubes when interacting with nickel, titanium, palladium and gold metal atoms. These interactions occurred via adsorption, intercalation, nitrogen substitutional doping and boron substitutional doping. The wide band gaps intrinsic to the pristine boron nitride nanotubes were successfully tuned upon interaction with the metal atoms irrespective of the type of interactions. However, for most of the interactions that occurred via intercalation and nitrogen substitutional doping, the boron nitride nanotube was found to possess semi-metallic properties. More states were added in the density of states upon interaction in which the d orbital of the transition metal atoms was found to be the major contributor to the increase in density of states.
关键词： Transition metals,Fermi energy,Density functional theory,Band gap,Boron nitride nanotubes
更新于2025-09-19 17:13:59
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Trifluoromethylation Enables a 3D Interpenetrated Low-Band-Gap Acceptor for Efficient Organic Solar Cells
摘要： Herein, tri?uoromethylation has proven to be an effective strategy for ultra-narrow band-gap NFAs. A PCE of 15.59% is achieved from BTIC-CF3-g-based devices, which is the highest value in reported ultra-narrow band-gap acceptors. A ternary device with 16.50% ef?ciency is also obtained, resulting from its red-shifted absorption. Meanwhile, the single-crystal structure of BTIC-CF3-g has been successfully presented, which gives a deep understanding of the solid-state molecular packings in these highly ef?cient acceptors.
关键词： ultra-narrow band-gap,nonfullerene acceptors,tri?uoromethylation,power conversion efficiency,organic solar cells
更新于2025-09-19 17:13:59
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Band Edge Tuning of Two-Dimensional Ruddlesdena??Popper Perovskites by A Cation Size Revealed through Nanoplates
摘要： Current understanding of the effects of various A site cations on the photophysical properties of halide perovskites (APbI3) is limited by the compositional tunability. Here we report the synthesis and characterization of colloidal nanoplates of a series of 2D Ruddlesden-Popper (RP) perovskites (HA)2(A)Pb2I7 (HA = n-hexylammonium) with seven small and large A site cations to reveal the size effects of such A cations. Absorbance and photoluminescence (PL) measurements show a clear parabolic trend of the optical band gap vs. the A cation size, with methylammonium and formamidinium near the bottom. This band gap shifting is attributed to the changing chemical pressure inside of the A site cavity templating the Pb-I framework. PL quantum yield and time resolved PL measurements show the effect of A cation size on the PL efficiencies and carrier lifetimes. This fundamental investigation can inform the choices of A site cations that can be incorporated into halide perovskite materials for optoelectronic applications.
关键词： chemical pressure,photoluminescence,A site cations,2D Ruddlesden-Popper perovskites,optical band gap
更新于2025-09-19 17:13:59
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What Is Limiting Pyrite Solar Cell Performance?
摘要： Iron pyrite (FeS2), an earth-abundant transition metal di-chalcogenide (TMD), has exotic electronic and optical properties suitable for solar cell applications. For example, it has an indirect band gap at (cid:1)0.95 eV and a direct band gap at 1.05–1.10 eV that is comparable to Si (1.1 eV), while absorption coef?cient of FeS2 is almost two orders of magnitudes higher than that of Si. Like Si, FeS2 solar cells also could have almost same theoretical energy conversion ef?ciency up to Shockley-Queisser limit. Additionally, the high absorption coef?cient of FeS2 offers the opportunities to fabricate a very thin absorber layer of thickness < 20 nm, which so far does not seem possible with other thin-?lm solar cell materials. It infers a sharp reduction of the production cost (￠/W) of electricity due to reduction of material cost. Consequently, FeS2 has gained interest as a potential non-toxic super absorber material in lieu of widely used but toxic and rare element containing CdTe and Cu(In, Ga)Se2 for thin-?lm solar cells.
关键词： super absorber,band gap,FeS2,solar cell,non-toxic,Iron pyrite,thin-film,absorption coefficient,photovoltaic
更新于2025-09-19 17:13:59
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Structure and luminescent properties of new Dy3+/Eu3+/Sm3+-activated InNbTiO6 phosphors for white UV-LEDs
摘要： A series of novel Dy3+/Eu3+/Sm3+-activated InNbTiO6 phosphors have been prepared by conventional solid state reaction method. Based on the structure refinement, RE3+ ions are preferred to occupy the site of In3+ (2e) in the wolframite-type host lattice. According to their UV–visible diffusion reflectance spectra, the band gap and absorption property of un-doped InNbTiO6 sample can be tuned by the dopants. Under UV–visible light excitation, Dy3+ activators in this matrix mainly show emission lines originating from their characteristic f→f transitions. The optimal excitation and emission wavelength are 385 nm and 581 nm for Dy3+, 394 nm and 616 nm for Eu3+, and 406 nm and 615 nm for Sm3+, respectively. Concentration quenching occurs at 0.06 for Dy3+, 0.06 for Eu3+, and 0.04 for Sm3+, ascribed to resonant q-q, q-q, and d-q interactions, respectively. The luminescence lifetimes are determined to be 0.13, 0.50, and 0.50 ms for InNbTiO6:0.06Dy3+, InNbTiO6:0.06Eu3+, and InNbTiO6:0.04Sm3+, respectively. The Dy3+, Eu3+, and Sm3+ doped phosphors exhibited yellowish-white, red, and orange-red luminescence, respectively. The quantum yields and thermal stability of representative phosphors have been investigated. Present work shows that these new phosphors are promising for application in UV-LED solid-state lighting devices.
关键词： Band gap,Absorption property,Luminescence,Crystal structure
更新于2025-09-19 17:13:59
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Non-layered ZnSb nanoplates for room temperature infrared polarized photodetectors
摘要： Non-layered 2D ZnSb nanoplates are successfully synthesized by chemical vapor deposition, which possess narrow band gap and novel anisotropic properties. Infrared polarized photodetectors based on the ZnSb nanoplates are designed and exhibit high responsivity, fast photoresponse speed, great stability, high anisotropic conductivity and linear polarization sensitivity.
关键词： anisotropic properties,ZnSb nanoplates,narrow band gap,chemical vapor deposition,infrared polarized photodetectors
更新于2025-09-19 17:13:59