scholarly journals Engineering the Color and the Donor-Acceptor Behavior in Nanowires: Blend Versus Coaxial Geometry

2020 ◽  
Author(s):  
Mohamed Mbarek ◽  
Kamel Alimi
Keyword(s):  
Thin Film ◽  
Charge Transfer ◽  
Shell Material ◽  
Time Resolved ◽  
Exciton Diffusion ◽  
The Core ◽  
Exciton Diffusion Length ◽  
Donor Acceptor ◽  
Time Resolved Photoluminescence ◽  
Thin Film Devices

The blending or the bilayering of two complementary species are the dominant methods for in-solution-processed thin film devices to get a strong donor-acceptor behavior. They propose opposite strategies for the respective arrangement of the two species, a central point for energy and/or charge transfer. In this work, we propose to engineer at the scale of the exciton diffusion length the organization of a donor (poly(vinyl-carbazole), PVK) and an acceptor (poly(para-phenylene-vinylene), PPV) in a nanowire geometry. A two-step template strategy was used to fabricate coaxial nanowires with PPV and PVK, alternatively as the core or the shell material. Their stationary and time-resolved photoluminescence properties were investigated and compared to the case of PVK-PPV blend. Their respective characteristics are direct evidences of the dominant mechanisms responsible for the emission properties.

scholarly journals Long-range exciton diffusion in non-fullerene acceptors and coarse bulk heterojunctions enable highly efficient organic photovoltaics

2020 ◽  
Vol 8 (31) ◽  
pp. 15687-15694
Author(s):  
Muhammad T. Sajjad ◽  
Arvydas Ruseckas ◽  
Lethy Krishnan Jagadamma ◽  
Yiwei Zhang ◽  
Ifor D. W. Samuel
Keyword(s):  
Long Range ◽  
Organic Photovoltaics ◽  
Diffusion Length ◽  
Three Dimensional ◽  
Accurate Estimate ◽  
Bulk Heterojunctions ◽  
Time Resolved ◽  
Exciton Diffusion ◽  
Exciton Diffusion Length ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence measurements provide an accurate estimate of the three-dimensional exciton diffusion length in three ITICs based non-fullerene acceptors (NFAs).

scholarly journals Horizontal versus vertical charge and energy transfer in hybrid assemblies of semiconductor nanoparticles

2012 ◽  
Vol 3 ◽  
pp. 629-636 ◽  
Author(s):  
Gilad Gotesman ◽  
Rahamim Guliamov ◽  
Ron Naaman
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Horizontal Plane ◽  
Quartz Substrate ◽  
Vertical Direction ◽  
Time Resolved ◽  
Transfer Processes ◽  
Donor And Acceptor ◽  
Hybrid Assemblies ◽  
Time Resolved Photoluminescence

We studied the photoluminescence and time-resolved photoluminescence from self-assembled bilayers of donor and acceptor nanoparticles (NPs) adsorbed on a quartz substrate through organic linkers. Charge and energy transfer processes within the assemblies were investigated as a function of the length of the dithiolated linker (DT) between the donors and acceptors. We found an unusual linker-length-dependency in the emission of the donors. This dependency may be explained by charge and energy transfer processes in the vertical direction (from the donors to the acceptors) that depend strongly on charge transfer processes occurring in the horizontal plane (within the monolayer of the acceptor), namely, parallel to the substrate.

scholarly journals Defect Characterization in ZnGeP2 by Time -Resolved Photoluminescence

1996 ◽  
Vol 450 ◽  
Author(s):  
N. Dietz ◽  
W. Busse ◽  
H. E. Gumlich ◽  
W. Ruderman ◽  
I. Tsveybak ◽  
...  
Keyword(s):  
Energy Range ◽  
Infrared Emission ◽  
Luminescence Spectra ◽  
Broad Emission Band ◽  
Wide Energy Range ◽  
Time Resolved ◽  
Broad Emission ◽  
Donor Acceptor ◽  
Donor States ◽  
Time Resolved Photoluminescence

AbstractSteady state and time-resolved photoluminescence (PL) investigations on ZnGeP2 crystals grown from the vapor phase by high pressure physical vapor transport (HPVT) and from the melt by gradient freezing (GF) are reported. The luminescence spectra reveal a broad infrared emission with peak position at 1.2 eV that exhibits features of classical donor-acceptor recombination. The hyperbolic decay characteristic over a wide energy range, investigated from 1.2 eV up to 1.5eV, suggest that this broad emission band is related to one energetic recombination center. Higher energetic luminescence structures at 1.6eV and 1.7eV were revealed after annealing of ZnGeP2 crystals in vacuum for a longer period of time. The emission decay behavior in this energy range is characterized by two hyperbolic time constants, viewed as the supercomposition of the decay from the broad emission center peaked at 1.2eV and additional donor-acceptor recombination emissions at 1.6eV and 1.7eV, respectively. ZnGeP2 crystals grown under Ge-deficient conditions by HPVT show an additional emission structure at 1.8 eV with sharp emission fine structures at 1.778 eV related to the presence of additional donor states.

scholarly journals Long-lived and disorder-free charge transfer states enable endothermic charge separation in efficient non-fullerene organic solar cells

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ture F. Hinrichsen ◽  
Christopher C. S. Chan ◽  
Chao Ma ◽  
David Paleček ◽  
Alexander Gillett ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Organic Solar Cells ◽  
Charge Separation ◽  
Free Charge ◽  
Charge Generation ◽  
Time Resolved ◽  
Thermodynamic Conditions ◽  
Donor Acceptor ◽  
Interfacial Charge

Abstract Organic solar cells based on non-fullerene acceptors can show high charge generation yields despite near-zero donor–acceptor energy offsets to drive charge separation and overcome the mutual Coulomb attraction between electron and hole. Here, we use time-resolved optical spectroscopy to show that free charges in these systems are generated by thermally activated dissociation of interfacial charge-transfer states that occurs over hundreds of picoseconds at room temperature, three orders of magnitude slower than comparable fullerene-based systems. Upon free electron–hole encounters at later times, both charge-transfer states and emissive excitons are regenerated, thus setting up an equilibrium between excitons, charge-transfer states and free charges. Our results suggest that the formation of long-lived and disorder-free charge-transfer states in these systems enables them to operate closely to quasi-thermodynamic conditions with no requirement for energy offsets to drive interfacial charge separation and achieve suppressed non-radiative recombination.

Time-resolved photoluminescence in CdIn2S4

1987 ◽  
Vol 65 (3) ◽  
pp. 204-207 ◽  
Author(s):  
S. Charbonneau ◽  
E. Fortin ◽  
J. Beauvais
Keyword(s):  
Single Crystals ◽  
Free Electron ◽  
Continuous Wave ◽  
Time Window ◽  
Photoluminescence Spectra ◽  
Time Resolved ◽  
Spectral Bands ◽  
Window Technique ◽  
Donor Acceptor ◽  
Time Resolved Photoluminescence

Photoluminescence spectra of CdIn2S4 single crystals at 1.8 K under both continuous-wave (CW) and pulsed excitation were obtained. In the latter case, a variable time-window technique was used to observe the time evolution of the spectra between 0 and 100 μs. In contrast to previous studies, four spectral bands were observed under both CW and pulsed, intrinsic or extrinsic excitation. In particular, two bands previously unobserved under extrinsic excitation were detected at 1.35 and 1.68 eV, and have been attributed to donor–acceptor pairs and free-electron to acceptor transitions respectively.

Fiber-fed time-resolved photoluminescence for reduced process feedback time on thin-film photovoltaics

2015 ◽  
Vol 86 (1) ◽  
pp. 013907 ◽  
Author(s):  
I. L. Repins ◽  
B. Egaas ◽  
L. M. Mansfield ◽  
M. A. Contreras ◽  
C. P. Muzzillo ◽  
...  
Keyword(s):  
Thin Film ◽  
Time Resolved ◽  
Thin Film Photovoltaics ◽  
Process Feedback ◽  
Time Resolved Photoluminescence ◽  
Feedback Time

scholarly journals Localized Surface Plasmon on 6H SiC with Ag Nanoparticles

2017 ◽  
Vol 897 ◽  
pp. 634-637
Author(s):  
Yi Wei ◽  
Ahmed Fadil ◽  
Hai Yan Ou
Keyword(s):  
Ag Nanoparticles ◽  
Internal Quantum Efficiency ◽  
Minority Carrier Lifetime ◽  
Fdtd Simulation ◽  
Localized Surface Plasmon ◽  
Ag Nanoparticle ◽  
Ag Nps ◽  
Time Resolved ◽  
Donor Acceptor ◽  
Time Resolved Photoluminescence

Silver (Ag) nanoparticles (NPs) were deposited on the surface of bulk Nitrogen-Boron co-doped 6H silicon carbide (SiC), and the Ag NPs were observed to induce localized surface plasmons (LSP) resonances on the SiC substrate, which was expected to improve the internal quantum efficiency (IQE) of the emissions of the donor-acceptor pairs of the SiC substrate. Room-temperature measurements of photoluminescence (PL), transmittance and time-resolved photoluminescence (TRPL) were applied to characterize the LSP resonances. Through the finite-difference time-domain (FDTD) simulation of the LSP resonance of an Ag nanoparticle on the SiC substrate, it is predicted that when the diameter of the cross section on the xy plane of the Ag nanoparticle is greater than 225 nm, the LSP starts to enhance the PL intensity. With implementation of a 3rd order exponential decay fitting model to the TRPL results, it is found that the average minority carrier lifetime of the SiC substrate decreased.

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