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Femtosecond Spectroscopy of Au Hot-Electron Injection into TiO2: Evidence for Au/TiO2 Plasmon Photocatalysis by Bactericidal Au Ions and Related Phenomena
摘要： In the present work, we provide evidence for visible light irradiation of the Au/TiO2 nanoparticles’ surface plasmon resonance band (SPR) leading to electron injection from the Au nanoparticles to the conduction band of TiO2. The Au/TiO2 SPR band is shown to greatly enhance the light absorption of TiO2 in the visible region. Evidence is presented for the light absorption by the Au/TiO2 plasmon bands leading to the dissolution of Au nanoparticles. This dissolution occurs concomitantly with the injection of the hot electrons generated by the Au plasmon into the conduction band of TiO2. The electron injection from the Au nanoparticles into TiO2 was followed by femtosecond spectroscopy. The formation of Au ions was further confirmed by the spectral shift of the transient absorption spectra of Au/TiO2. The spectral changes of the SPR band of Au/TiO2 nanoparticles induced by visible light were detected by spectrophotometer, and the morphological transformation of Au/TiO2 was revealed by electron microscopy techniques as well. Subsequently, the fate of the Au ions was sorted out during the growth and biofilm formation for some selected Gram-negative bacteria. This study compares the bactericidal mechanism of Au ions and Ag ions, which were found to be substantially different depending on the selected cell used as a probe.
关键词： electron injection,antibacterial effects,genes expression,DNA repair,quorum sensing,plasmon photocatalysis,biofilms,gold nanoparticles,porins
更新于2025-11-21 11:20:42
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Diphenylisobenzofuran Bound to Nanocrystalline Metal Oxides: Excimer Formation, Singlet Fission, Electron Injection, and Low Energy Sensitization
摘要： We report the photophysical properties of the dicarboxylated diphenylisobenzofuran dye (1) bound to nanocrystalline metal oxide surfaces. With increased surface loading of 1, emission from the films is significantly quenched but with a small amount of excimer emission at maximum surface loadings. Long-lived triplets were observed by ns TA spectroscopy that is consistent with singlet fission occurring on mesoporous ZrO2. The evolution of these triplets however could not be convincingly resolved by our sub-nanosecond TA spectroscopy. Dye-sensitized devices composed of 1 on a TiO2|Al2O3 core-shell structure exhibited an unusual decrease, increase, and then decrease in Jsc with respect to the thickness of Al2O3. In these films the Al2O3 acts as a tunneling barrier to slow electron injection from the singlet excited state such that singlet fission, and electron injection from the triplet state become competitive. Proof-of-principle self-assembled bilayer films that exhibit efficient triplet energy transfer from a low energy absorbing dye to 1 is demonstrated as another step towards a SF-based DSSC that can circumvent the Shockley-Queisser limit.
关键词： low energy sensitization,excimer formation,singlet fission,electron injection,diphenylisobenzofuran,nanocrystalline metal oxides
更新于2025-09-23 15:21:21
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[SpringerBriefs in Applied Sciences and Technology] Air-Stable Inverted Organic Light-Emitting Diodes || Carrier Injection Mechanism
摘要： Both hole and electron injection layers are commonly used in recent OLEDs to reduce the injection barrier between electrodes and organic layers. This injection barrier originates from the energy difference between the work function (WF) of the electrode and the energy level of the organic layer. For instance, the hole injection barrier is defined as the energy difference between the Fermi level of the anode and the highest occupied molecular orbital (HOMO) level of the organic layer on the anode, as shown in Fig. 4.1a. Thus, an ideal hole injection material is the material that can make the surface WF of the anode larger (Fig. 4.1b). On the other hand, an ideal electron injection material is the material that can make the surface WF of the cathode smaller (Fig. 4.1c).
关键词： energy level alignment,OLEDs,electron injection,hole injection,work function
更新于2025-09-23 15:21:01
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Theoretical modifications of the molecular structure of Aurantinidin and Betanidin dyes to improve their efficiency as dye-sensitized solar cells
摘要： Two modifications of the molecular structures of Aurantinidin and Betanidin dyes were modeled, and the optical and electrical properties were calculated by using density functional theory (DFT) and time-dependent DFT (TD–DFT). The modification of the structures was done by connecting the units through vinyl groups and using regular electron acceptor and electron donor moieties to the original structures. It has been demonstrated that the modifications improved the electron injection properties of the molecules with higher light-harvesting efficiencies, an increase in the driving force of electron injection ( ΔG inject ) and open-circuit photovoltages ( V OC ).
关键词： DSSC,DFT,Frontier molecular orbitals,Electron injection,TD–DFT
更新于2025-09-23 15:21:01
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Boosting the Efficiency and Curtailing the Efficiency Roll-off in Green Perovskite Light-Emitting Diodes via Incorporating Ytterbium as Cathode Interface Layer
摘要： Perovskite light-emitting diodes (PeLEDs) exhibit high external quantum efficiencies (EQEs), emerging as a next-generation technology for lighting and display applications. Nevertheless, they suffer from severe efficiency roll-off at high luminance, particularly in case of blue and green emissions, which is one of the major bottlenecks in their industrial applications. Here, we attack this problem using a rare-earth metal, Yb, as cathode interface layer (CIL) for green PeLEDs. By adopting a new device configuration of ITO/TFB/FA-based Quasi-2D Perovskite/TPBi/Yb/Ag, we achieved a peak current efficiency (CE) of 22.3 cd/A with a corresponding EQE of 5.28% and a high maximum luminance of 19,160 cd/m2. Importantly, the maximum CE of 22 cd/A at 2,000 cd/m2 slightly decreased to 16.8 cd/A at 5,000 cd/m2 and maintained a still decent value of 12 cd/A at a very high luminance of 10,000 cd/m2, exhibiting a remarkably low efficiency roll-off. Our Yb-incorporated devices significantly outperformed the PeLEDs containing conventional CILs, including Mg and Liq, in terms of peak efficiency, efficiency roll-off and operational lifetime. We attribute this encouraging performance to barrier-free, efficient electron injection enabled by the low work function of Yb (2.6 eV) which led to a high electron current, nearly approaching the hole current in hole-dominant PeLEDs, as confirmed by the single-carrier device measurements. In addition, we also present Yb-incorporated PeLEDs containing Cs-based Quasi-2D perovskite as the emissive layer which displayed an impressive CE of 51.3 cd/A with a corresponding EQE of 16.4% and a maximum luminance of 14,240 cd/m2, and still demonstrated a reduced efficiency roll-off comparing to that of the Liq-based equivalent. These results unveil the inspiring prospects of Yb as an efficient CIL for PeLEDs towards high efficiency with reduced efficiency roll-off.
关键词： electron injection,ytterbium,quasi-2D,perovskite light-emitting diodes,stability,cathode interface layer,efficiency roll-off
更新于2025-09-23 15:21:01
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Unified theory of plasmon-induced resonance energy transfer and hot electron injection processes for enhanced photocurrent efficiency
摘要： Plasmons in metal nanoparticles (MNPs) promise to enhance solar energy conversion in semiconductors. Two essential mechanisms of enhancement in the near-field regime are hot electron injection (HEI) and plasmon-induced resonance energy transfer (PIRET). Individual studies of both mechanisms indicate that the PIRET efficiency is limited by the short lifetime of the plasmon, whereas the hot electrons result from the plasmon decay. The development of a unified theory of the coupled HEI and PIRET processes is fundamentally interesting and necessary for making reliable predictions but is complicated by the multiple interactions between various components that participate in the enhancement process. In this paper, we use the model-Hamiltonian approach to develop a combined theoretical framework including both PIRET and HEI. The coupled dynamics as well as the time evolution of hot electron energy distribution are studied. The theory further predicts an interference-induced asymmetry in the spectral dependence of PIRET, which can be used to distinguish it from HEI. As the relative contributions of PIRET and HEI strongly depend on the size of the MNPs, this presents itself as a simple route to control the strength of their contributions. The results presented here can further guide future applications of plasmonic solar energy harvesting.
关键词： plasmon,metal nanoparticles,hot electron injection,solar energy conversion,plasmon-induced resonance energy transfer
更新于2025-09-23 15:21:01
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Aromatic amine passivated TiO2 for dye-sensitized solar cells (DSSC) with ~9.8% efficiency
摘要： In this work, the e?ciency of dye-sensitized solar cells (DSSC) was improved by capping TiO2 with simple aromatic amines as a complexing agent. The aromatic amines, aniline and o-phenylenediamine capped TiO2 composites were synthesized via hydrothermal route and used as scattering layer in dye-sensitized solar cell (DSSC). Markedly, the maximum photo-conversion e?ciency of 9.84% was achieved with o-phenylenediamine capped-TiO2 composite as o-phenylenediamine capped-TiO2 showed higher re?ectivity than the pristine TiO2, which is highly bene?cial for re?ecting the photons back to photoanode. In addition, the average life time of carriers in o-phenylenediamine capped-TiO2 was found to be 9.8 ms, which was 2 times higher than the pristine TiO2 (4.29 ms).
关键词： Aromatic amines,DSSC,Scattering layer,Electron injection,TiO2,Lifetime
更新于2025-09-23 15:21:01
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Tuning the Color Palette of Semi-Transparent Solar Cells via Lateral ??-Extension of Polycyclic Heteroaromatics of Donora??Acceptor Dyes
摘要： Durable solar cells with tunable color and diaphaneity are very promising for building integrated photovoltaic applications. In this paper we employ donor–acceptor organic dyes U3, U4, U5, and R6 featured by polycyclic heteroaromatics 6,12-dihydroindeno[1,2-b]indeno[2',1':4,5]thieno[2,3-d]thiophene (IT2), 7,15-dihydrobenzo[6',7']indeno[2',1':4,5]thieno[3,2-b]benzo[6,7]indeno[2,1-d]thiophene (BIT2), 7,15-dihydrophenaleno[1,2-b]phenaleno[2',1':4,5]thieno[2,3-d]thiophene (PT2), and 9,19-dihydrobenzo[1',10']phenanthro[3',4':4,5]thieno[3,2-b]benzo[1,10]phenanthro[3,4-d]thiophene (BPT2) to fabricate semi-transparent dye-sensitized solar cells (DSSCs). The U3, U4, U5, and R6 based cells are goldenrod, crimson, red, and sapphire blue, with power conversion efficiencies of 3.5%, 8.2%, 7.6, and 10.1% at the AM1.5G conditions. Density functional theory calculation and voltammetric measurement reveal that lateral π-extension of polycyclic heteroaromatic brings forth a downward displacement of lowest unoccupied molecular orbital, affording a high molar extinction coefficient, low-energy gap blue dye. Femtosecond fluorescence decay measurements of dyed titania and alumina films unravel the electron injection yields of photo-excited dye molecules, which are well correlated with the maximal values of external quantum efficiencies of DSSCs. After 1,000 h full sunlight soaking at 60 oC, the red and blue DSSCs exhibit stable photocurrents, owing to the strong bonding and photochemical stability of dye molecules adsorbed on the surface of titania as well as the retention of close-to-unity electron collection yield.
关键词： electron injection,durability,tunable color,semi-transparent solar cell,lateral π-extension,photosensitizer
更新于2025-09-23 15:19:57
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Design of Tandem Organic Light Emitting Diode using efficient charge generation layer
摘要： In this work, highly e?cient Tandem Organic Light Emitting Diode (OLED) based on planar organic charge generation layer (CGL) of C70/Pentacene is proposed. It is found that the proposed CGL generate charges as well as exhibits organic photovoltaic type behavior. In addition a very thin layer of Al/LiF and PEDOT:PSS is used as electron and hole injection layer respectively to further increase the transport of electrons and holes from CGL to emissive unit. The current e?ciency and luminance of red tandem device is found to be 29 cd/A and 29010 cd/m2 at 20 mA/cm2 and 100 mA/cm2 respectively which is 1.855 times 1.856 times greater than that of single emitter device having current e?ciency and luminance of 15.63 cd/A and 15630 cd/cm2 at the same current densities Generally, the turn on voltage of Tandem devices is almost double as compared to single unit device. But with the proposed CGL the turn on voltage of red tandem device is found to be 5.9 V which is less than double the turn on voltage of single unit device (3 V). Therefore, the e?ective charge generation and transport property of proposed CGL as well as remarkable high injection property of thin Al layer and PEDOT:PSS leads to the enhancement in the e?ciency of tandem OLED.
关键词： Tandem OLED,Charge generation layer,Electron injection,E?ciency improvement
更新于2025-09-23 15:19:57
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Organic-inorganic hybrid composites as an electron injection layer in highly efficient inverted green-emitting polymer LEDs
摘要： Organic-inorganic hybrid light emitting diodes (HyLEDs) consist of an organic emission layer in combination with at least one metal oxide charge injection layer in an inverted structure. Low temperature, solution processing of metal oxide charge injection layers is one of the key factors in reducing the manufacture cost of HyLEDs. Herein, we report the use of composite materials, comprising conjugated polyelectrolytes (CPE) and zinc oxide nanoparticles (ZnO NPs), as the electron injection layer (EIL) in highly-efficient, green-light-emitting poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) polymer LEDs that are carefully optimised for use in an inverted HyLED architecture for the first time. The composite CPE:ZnO EILs are processed via a room temperature, one-step, solution deposition and enable superior device performance relative to ZnO NPs on their own. We find that specifically, they (i) improve EIL morphology, reducing surface roughness as well as pin-hole size and density, (ii) induce a favourable vacuum level shift for electron injection by coordinate bonding between the CPE and ZnO constituents, and (iii) reduce interfacial quenching by passivation of ZnO chemical defects caused by oxygen vacancies. This work is also the first demonstration that blending ZnO NPs and CPE supports much faster electroluminescence turn-on times (~7.12 μs) than for traditional ZnO/CPE bilayer devices (~0.4 s) via ‘locking’ of the CPE mobile ions, as well as higher device performance. This demonstrates good suitability for display applications. After optimisation of the EIL composition and the thickness of the F8BT emissive layer, we achieve promising device efficiencies of 16.5 cd/A and 5.41 lm/W for devices with a 1.1 μm thick F8BT layer, which is particularly relevant for potential roll-to-roll fabrication. These results clearly demonstrate the potential that this organic-inorganic composite EIL material has for the realisation of cheap, scalable and highly efficient, printable HyLED devices.
关键词： inverted,Hybrid light-emitting diodes,nanoparticles,electron injection layers,conjugated polyelectrolytes,zinc oxide
更新于2025-09-19 17:13:59