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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • Signal-to-Noise Ratio (SNR)
  • Infinite Gain Multiple Feedback (IGMF)
  • Visible Light Communications (VLC)
  • LED
  • Trans-Impedance Amplifier (TIA)
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • University of Northumbria
  • University of Huddersfield
29 条数据
?? 中文（中国） ▾

  • Study of (AgxCu1a??x)2ZnSn(S,Se)4 monograins synthesized by molten salt method for solar cell applications

    摘要： The open circuit voltage (VOC) deficit of Cu2ZnSn(S,Se)4 (CZTSSe) kesterite solar cells is higher than that of the closely related Cu(InGa)Se2 solar cells. One of the most promising strategies to overcome the large VOC deficit of kesterite solar cells is by reducing the recombination losses through appropriate cation substitution. In fact, replacing totally or partially Zn or Cu by an element with larger covalent radius one can significantly reduce the concentration of I–II antisite defects in the bulk. In this study, an investigation of the impact of partial substitution of Cu by Ag in CZTSSe solid solution monograins is presented. A detailed photoluminescence study is conducted on Ag-incorporated CZTSSe monograins and a radiative recombination model is proposed. The composition and structural quality of the monograins in dependence of the added Ag amount are characterized using Energy Dispersive X-ray Spectroscopy and X-Ray Diffraction method, respectively. The Ag-incorporated CZTSSe monograin solar cells are characterized by temperature dependent current-voltage and electron beam induced current methods. It was found, that low Ag contents (x ≤ 0.02) in CZTSSe lead to higher solar cell device efficiencies.

    关键词： Copper zinc tin sulfur selenide,Monograins,Electron beam induced current,Photoluminescence,Kesterite,Cations substituation

    更新于2025-11-21 10:59:37

  • Reorientational dynamics of organic cations in perovskite-like coordination polymers

    摘要： Here we report the dynamics of organic cations as guest molecules in a perovskite host-framework. The molecular motion of CH3NH3+ (MAFe), (CH3)2NH2+ (DMAFe) and (CH3)3NH+ (TrMAFe) in the cage formed by KFe(CN)63? units was studied using a combination of experimental methods: (i) thermal analysis, (ii) dielectric and electric studies, (iii) optical observations, (iv) EPR and 1H NMR spectroscopy and (v) quasielastic neutron scattering (QENS). In the case of MAFe and TrMAFe, the thermal analysis reveals one solid-to-solid phase transition (PT) and two PTs for the DMAFe crystal. A markedly temperature-dependent dielectric constant indicates the tunable and switchable properties of the complexes. Also, their semiconducting properties are confirmed by a dc conductivity measurement. The broadband dielectric relaxation is analyzed for the TrMAFe sample in the frequency range of 100 Hz–1 GHz. QENS shows that we deal rather with the localized motion of the cation than a diffusive one. Three models, which concern the simultaneous rotation of the CH3 and/or NH3 group, π-flips and free rotations of the organic cation, are used to fit the elastic incoherent structure factor. The 1H NMR spin–lattice relaxation time for all compounds under study, as well as the second moments, has been measured in a wide temperature range. In all studied samples, the temperature dependence of the second moment of the proton NMR line indicated the gradual evolution of the molecular movements from the rigid state up to a highly disordered one.

    关键词： quasielastic neutron scattering,phase transitions,perovskite,coordination polymers,dielectric properties,NMR spectroscopy,dynamics,organic cations

    更新于2025-11-14 17:28:48

  • Novel π-conjugated systems based on pyrimidine N-Oxide

    摘要： Pyrimidine N-oxide moiety for the first time was used as a heterocyclic core for the construction of π-conjugated molecules with fluorescent properties. For the synthesis of the title compounds a simple two-step protocol starting from readily available 4-fluoro-2-methylpyrimidine N-oxides was elaborated. A series of 17 novel pyrimidine N-oxide derivatives containing various functional substituents and π-conjugated systems of different length were obtained. The title compounds revealed fluorescent properties in visible region, possessing emission maximum up to 575 nm. Deoxygenation of the N-oxide group led to the loss of visible fluorescence. The chemosensor properties towards TFA and a number of metal cations were demonstrated for 3a, the first representative of the title series. Cytotoxic activity against breast adenocarcinoma cell line was found for three pyrimidine N-oxide derivatives 3b,i,n. Pyrimidine N-oxide 3a was shown to possess excellent biocompatibility and capability to enter cells, that makes it a promising structure for development of bioimaging fluorescent probes.

    关键词： Anticancer activity,Pyrimidines,π-Conjugated systems,Fluorescence,Knoevenagel condensation,Metal cations

    更新于2025-09-23 15:23:52

  • How the Mixed Cations (Guanidium, Formamidinium, and Phenylethylamine) in Tin Iodide Perovskites Affect Their Charge Carrier Dynamics and Solar Cell Characteristics

    摘要： Despite recent interest in lead-free Sn iodide perovskite (ASnI3) solar cells, the role of mixed A-site cations is yet to be fully understood. Here, we report the effect of the ternary mixing of organic A-site cations (guanidium, GA; formamidinium, FA; and phenylethylamine, PEA) on the solar cell performance and charge carrier dynamics that are evaluated using time-resolved microwave conductivity (TRMC). (GAxFA1?x)0.9PEA0.1SnI3 exhibits the maximum power conversion efficiency (PCE) of 7.90% at x = 0.15 and a drastic decrease with increasing GA content. Notably, our TRMC measurements of ASnI3 with/without a hole transport layer reveal the same trend with the devices. From the analyses, we suggest that a variation of electron mobility affected by the location of the GA cation in the grains significantly impacts the PCE. Our work sheds light on the role of mixed A-site cations and directs a route toward the further development of Sn perovskite solar cells.

    关键词： time-resolved microwave conductivity,mixed A-site cations,solar cell performance,Sn iodide perovskite,charge carrier dynamics,lead-free

    更新于2025-09-23 15:21:01

  • Ambient air-processed mesoscopic solar cells based on methylammonium and phenethylammonium quasi-2D/3D perovskites

    摘要： The instability of perovskite solar cells under ambient conditions leads many scientific groups to produce their solar cell devices under controllable, yet, expensive conditions. In this work, a mesoscopic solar cell device produced under ambient air/temperature conditions and relatively high humidity is presented. The active material is based on methylamine, phenethylamine, lead(II) iodide and lead(II) chloride. Furthermore, a bis(trifluoromethane)sulfonimide lithium (Li-TFSI) salt layer was used as a dopant onto mesoscopic TiO2, while the hole-transport material used was the popular poly(3-hexylthiophene-2,5-diyl) (P3HT) polymer. All layers were deposited by simple spin coating technique, while the whole process took place under 40–60% relative humidity–ambient conditions. The sequential deposited perovskite layer was built by a 3D mixed halide (CH3NH3)3PbI3Cl2 layer on top of a mixed 3D/Quasi-2D perovskite (CH3NH3)3PbI3Cl2–(C8H9NH3)2(CH3NH3)2Pb3I10 layer. These specific perovskites were used to take advantage of the well-known power conversion efficiency (PCE) of the mixed halide perovskite based on methylamine, and the proven reproducibility and stability of the phenethylamine-based perovskites, especially under non-controllable conditions. The champion mesoscopic device presented a PCE of 13.22%, with short circuit current density (JSC) of 23.67 mA/cm2, open circuit voltage (VOC) of 1034 mV and fill factor (FF) 0.54.

    关键词： Mesoscopic structure,Methylamine–phenethylamine mixed cations,Hybrid organic–inorganic semiconductors,Ambient conditions,Perovskites,Mesoporous solar cells

    更新于2025-09-23 15:21:01

  • Interface passivation treatment by halogenated low-dimensional perovskites for high-performance and stable perovskite photovoltaics

    摘要： The voltage loss which is mainly caused by the nonradiative recombination at the interface has played a serious negative effect on the photovoltaic performance of perovskite solar cells (PSCs). Herein, we firstly designed four halogenated layers by the way of employing different benzylammonium-based aromatic cations for high-performance devices. The introduction of halogen functional groups can not only enhance the hydrophobicity but also optimize the photovoltaic characteristics of LDP which play an important role on passivation effect of the interface between perovskite and hole transport materials (HTM) layer. The films with halogenated LDP passivation layers displayed suppressed nonradiative recombination and reduced trap density, leading to significantly reduced voltage loss. As a result, the optimal devices with 4-bromobenzylammonium-based LDP layer achieved the power conversion efficiency (PCE) as high as 21.13% with an enhanced open-circuit voltage (Voc) of 1.14 V. Under the hydrophobic and buffer action of the halogenated LDP layer, the modified devices showed outstanding long-term stability when exposed to moisture, heat and continuous UV irradiation. This work proves the enhanced passivation effect of LDP layer by regulating the chemical property of introduced organic cations for high-performance and stable perovskite photovoltaics.

    关键词： Low-dimensional perovskite,Perovskite solar cells,Halogenated cations,Passivation effect,Photovoltaic performance

    更新于2025-09-23 15:21:01

  • Three-dimensional Lead Iodide Perovskitoid Hybrids with High X-ray Photoresponse

    摘要： Large organic A cations cannot stabilize the 3D perovskite AMX3 structure because they cannot be accommodated in the cubo-octhedral cage (do not follow the Goldschmidt tolerance factor rule), and they generally template low-dimensional structures. Here we report that the large di-cation aminomethylpyridinium (AMPY), can template novel 3D structures which resemble conventional perovskites. They have the formula (xAMPY)M2I6 (x = 3 or 4, M = Sn2+ or Pb2+) which is doubled the AMX3 formula. However, because of the steric requirement of the Goldschmidt tolerance factor rule, it is impossible for (xAMPY)M2I6 to form proper perovskite structures. Instead, a combination of corner-sharing and edge-sharing connectivity is adopted in these compounds leading to the new 3D structures. DFT calculations reveal that the compounds are indirect-bandgap semiconductors with direct bandgaps presenting at slightly higher energies and dispersive electronic bands. The bandgaps of the Sn and Pb compounds are ~ 1.7 eV and 2.0 eV, respectively, which is slightly higher than the corresponding AMI3 3D perovskites. The Raman spectra for the compounds are diffuse, with a broad rising central peak at very low frequencies around 0 cm-1, a feature that is characteristic of dynamical lattices, highly anharmonic, and dissipative vibrations very similar to the 3D AMX3 perovskites. Devices of (3AMPY)Pb2I6 crystals exhibit clear photoresponse under ambient light without applied bias, reflecting a high carrier mobility (μ) and long carrier lifetime (τ). The devices also exhibit sizable X-ray generated photocurrent with a high μτ product of ~1.2×10-4 cm2 /V and an X-ray sensitivity of 207 μC·Gy-1·cm-2.

    关键词： Metal halide hybrids,mixed cations,photoresponse,X-ray detector,anomalous bandgap behavior

    更新于2025-09-23 15:19:57

  • Controlling films structure by regulating 2D Ruddlesden-Popper perovskite formation enthalpy for efficient and stable tri-cation perovskite solar cells

    摘要： The incorporation of bulky organic cations to metal-halide perovskites, forming the 2D-3D heterojunctions, has dramatically improved the stability of perovskite solar cells (PSCs). Nevertheless, the power conversion efficiencies (PCEs) of these PSCs are typically sacrificed because the formed 2D structures possess larger dielectric confinement, wider bandgaps, higher exciton binding energies and lower charge-carrier mobilities than the 3D perovskites. Here, we demonstrate that the environmental stability of the PSCs could be significantly improved without sacrificing the efficiency by introducing hydrophobic polyfluorinated cations (CF3CF2CH2NH3+, 5F-PA+) to the metal-halide perovskites. Due to the large 2D perovskite formation enthalpy with polyfluorinated cations, the addition of such cations will form a protective layer at the grain boundaries of 3D perovskite rather than form the 2D perovskites. The resultant solar cells based on 5F-PA0.05[Cs0.05(MA0.17FA0.83)0.95]0.95Pb(Br0.17I0.83)3 exhibit a substantially increased PCE of 22.86% compared with that (20.69%) of the control Cs0.05(MA0.17FA0.83)0.95Pb(Br0.17I0.83)3 devices. More importantly, the optimized devices could keep 80% of their original PCEs after >3000 h in ambient environment with 65 ± 10% relative humidity, which is attributed to hydrophobic fluorine moieties.

    关键词： power conversion efficiency,perovskite solar cells,environmental stability,polyfluorinated cations,2D-3D heterojunctions

    更新于2025-09-23 15:19:57

  • Phase control of quasi-2D perovskites and improved light-emitting performance by excess organic cations and nanoparticle intercalation

    摘要： The optoelectronic properties of quasi-two-dimensional organic–inorganic hybrid perovskites can be tuned by controlling the formation of Ruddlesden–Popper type phases, which enables diverse device applications such as photovoltaics and light-emitting diodes (LEDs). Herein, the influence of excess organic cations on the phase formation of (PEA)2MAn?1PbnBr3n+1 is systematically investigated with various mixing ratios to discover the phase distribution beneficial for light-emitting diodes. It is found that PEA cations exceeding Pb ions in molar ratio are required to produce small-n phases in the films with a strong photoluminescence, while excess MA cations enable the formation of more large-n phases. Low electrical conductivity inherent to the properties of quasi-2D perovskites is further lowered by the introduction of excess organic cations. This is overcome by the intercalation of zinc oxide (ZnO) nanoparticles (NPs) into the blocking layers composed of PEA cations. Importantly, these metal oxide NPs also modulate the phase distribution, enabling the realization of bright green quasi-2D perovskites with a better stability and a maximum luminance of nearly 60 000 cd m?2, which is the highest brightness compared to the so far reported quasi-2D perovskite LEDs incorporating organic cations.

    关键词： phase control,excess organic cations,nanoparticle intercalation,light-emitting diodes,quasi-2D perovskites

    更新于2025-09-19 17:15:36

  • Widening the 2D/3D Perovskite Family for Efficient and Thermal-Resistant Solar Cells by the Use of Secondary Ammonium Cations

    摘要： While 2D/3D layered perovskites have been the object of comprehensive research principally focused on increasing the long-term stability observed in 3D perovskites, significant opportunities still exist concerning the application of different kinds of cations outside the sphere of primary amines, which are the cations most usually applied. Our results demonstrate that the materials and the solar cells prepared with dipropylammonium iodide (DipI), a bulky secondary ammonium cation of small size, lead to obtaining materials that are not only efficient and thermodynamically stable but also robust toward heat stress. Time-resolved studies indicate longer carrier lifetime for 2D/3D layered perovskites fabricated with this bulky cation than for systems based on bulky primary ammonium cations, which allowed us to obtain PCE = 12.51% (n = 10), 15.78% (n = 50), and 17.90% (n = 90). We determine that the concentration of perovskite material after 240 min at 100 °C is up to 575% greater in the 2D/3D perovskite (n = 10) than that observed in 3D perovskite films. The material stability also improves the thermal stability of the photovoltaic devices, presenting an efficiency drop of just 4% for n = 50 and n = 10 after thermal annealing while the performance drop for reference 3D samples in the same conditions was greater than 80%.

    关键词： carrier lifetime,2D/3D perovskites,solar cells,thermal stability,secondary ammonium cations

    更新于2025-09-19 17:13:59