Energy and Charge Transfer in Electroluminescent Polymer/Porphyrin Blends

1999 ◽  
Vol 558 ◽  
Author(s):  
V. Cleave ◽  
G. Yahioglu ◽  
P. Le Barny ◽  
R.H. Friend ◽  
N. Tessler ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Charge Separation ◽  
Emission Spectra ◽  
Time Resolved ◽  
Show Evidence ◽  
Homo And Lumo ◽  
Lumo Level ◽  
Photoluminescence Efficiency ◽  
Absorption Measurements ◽  
Triplet Excitons

ABSTRACTWe present a study of the effects of blending electroluminescent polymers with platinum (II) octaethylporphyrin (PtOEP). We find that in the case of polymers which are measured to have HOMO and LUMO levels respectively below and above those of the PtOEP, and which have emission spectra overlapping the PtOEP absorption spectra, energy transfer occurs as expected. We find further evidence, in the form of steady state and time-resolved electroluminescence and photoluminescence measurements, which indicates additional transfer of triplet excitons between polymer and porphyrin. Where the polymers have emission spectra overlapping the absorption spectra of PtOEP, but which are measured to have a HOMO or LUMO level between those of the porphyrin, quenching of the photoluminescence efficiency occurs. We propose this is due to charge separation between the porphyrin and the polymer, and show evidence for this in the form of photoinduced absorption measurements.

Energy and Charge Transfer in Electroluminescent Polymer/Porphyrin Blends

1999 ◽  
Vol 560 ◽  
Author(s):  
V. Cleave ◽  
G. Yahioglu ◽  
P. Le Barny ◽  
R.H. Friend ◽  
N. Tessler ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Charge Separation ◽  
Emission Spectra ◽  
Time Resolved ◽  
Show Evidence ◽  
Homo And Lumo ◽  
Lumo Level ◽  
Photoluminescence Efficiency ◽  
Absorption Measurements ◽  
Triplet Excitons

ABSTRACTWe present a study of the effects of blending electroluminescent polymers with platinum (II) octaethylporphyrin (PtOEP). We find that in the case of polymers which are measured to have HOMO and LUMO levels respectively below and above those of the PtOEP, and which have emission spectra overlapping the PtOEP absorption spectra, energy transfer occurs as expected. We find further evidence, in the form of steady state and time-resolved electroluminescence and photoluminescence measurements, which indicates additional transfer of triplet excitons between polymer and porphyrin. Where the polymers have emission spectra overlapping the absorption spectra of PtOEP, but which are measured to have a HOMO or LUMO level between those of the porphyrin, quenching of the photoluminescence efficiency occurs. We propose this is due to charge separation between the porphyrin and the polymer, and show evidence for this in the form of photoinduced absorption measurements.

Photoinduced electron transfer processes in three component rotaxanes with porphyrins, [60]fullerene and triphenylamine

2006 ◽  
Vol 10 (12) ◽  
pp. 1346-1359 ◽  
Author(s):  
Hisahiro Sasabe ◽  
Yoshio Furusho ◽  
Atula S.D. Sandanayaka ◽  
Yasuyuki Araki ◽  
Nobuhiro Kihara ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Charge Separation ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Solvent Polarity ◽  
Time Resolved ◽  
Transfer Processes ◽  
Back Electron Transfer ◽  
Electron Transfer Processes ◽  
Absorption Measurements

Electron transfer processes occurring through-space and through-bond were studied for novel mechanically linked triad [2]rotaxanes, which contain a porphyrin (MP) unit as a pendant and [60]fullerene ( C 60) and triphenylamine ( TPA ) moieties as stopper groups at the axle ends (abbreviated as ( MP ; C 60- TPA ) rot+ with MP = H 2 P or ZnP . The photophysical properties were investigated by means of time-resolved fluorescence and transient absorption measurements with changing solvent polarity. The charge separation took place mainly via(1 MP *; C 60- TPA ) rot+ and ( MP ;1 C 60*- TPA ) rot + in polar solvents. Within the charge-separated states of triads ( MP ; C 60- TPA ) rot +, hole-shift and/or back electron transfer took place competitively. The lifetime of the charge separation state of ( ZnP ; C 60- TPA ) rot+ was similar to that of dyad ( C 60- TPA ) rot+ (140 ns in dimethylformamide), whereas that of ( H 2 P ; C 60- TPA ) rot + was as long as 230 ns, suggesting two final charge separation states such as ( MP ; C 60•-- TPA •+) rot + and ( MP •+; C 60•-- TPA ) rot+ depending on the kind of porphyrin.

Photoinduced electron and energy transfer processes in rotaxanes containing zinc porphyrin as pendant and [60]fullerene and ferrocene as axle ends

2005 ◽  
Vol 09 (10) ◽  
pp. 724-734 ◽  
Author(s):  
Mio Maes ◽  
Hisahiro Sasabe ◽  
Nobuhiro Kihara ◽  
Yasuyuki Araki ◽  
Yoshio Furusho ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Charge Separation ◽  
Transient Absorption ◽  
Recombination Rates ◽  
Time Resolved ◽  
Transient Absorption Spectra ◽  
Transfer Processes ◽  
Nonpolar Solvents ◽  
Electron Transfer Processes ◽  
Absorption Measurements

Photoinduced electron-transfer processes of a newly synthesized rotaxane containing porphyrinatozinc ( ZnP ), [60]fullerene ( C 60), and ferrocene ( Fc ) have been studied in terms of the time-resolved fluorescence and transient absorption measurements in polar and nonpolar solvents. In this rotaxane, ( ZnP ; C 60- Fc ) rotax , ZnP was chosen as a pendant of a crown-ether necklace, through which an axle with C 60 and Fc at both termini was penetrated. By the selective excitation of the ZnP moiety in a nonpolar solvent, energy transfer predominantly takes place to the C 60 moiety of ( ZnP ; C 60- Fc ) rotax . In polar solvents, charge-separation process takes place via the excited singlet state of the ZnP moiety in addition to the energy-transfer process. From the nanosecond transient absorption spectra, a clear absorption band of the C 60•− moiety was observed at 1000 nm as well as a broad absorption in the 600-800 nm region due to ZnP •+, suggesting the generation of ( ZnP •+; C 60•−- Fc ) rotax in the first step. Afterward, the hole-transferring process from ZnP •+ to Fc is thermodynamically possible, although this process is not fast because of its through-space process character. The final lifetimes of the C 60•− moiety were evaluated to be 290 and 370 ns in benzonitrile and DMF, respectively. The ratios of the charge-separation rates to charge-recombination rates were ca. 1000, indicating that ( ZnP ; C 60- Fc ) rotax affords an efficient photosynthetic model.

Optical, electrochemical and third-order nonlinear optical studies of triphenylamine substituted zinc phthalocyanine

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1173-1181 ◽  
Author(s):  
Narra Vamsi Krishna ◽  
Puliparambil Thilakan Anusha ◽  
S. Venugopal Rao ◽  
L. Giribabu
Keyword(s):  
Nonlinear Optical ◽  
Emission Spectra ◽  
Optical Emission ◽  
Soret Band ◽  
Laser Pulses ◽  
Zinc Phthalocyanine ◽  
Third Order ◽  
Time Resolved ◽  
Nlo Properties ◽  
Scan Data

Zinc phthalocyanine possessing triphenylamine at its peripheral position has been synthesized and its optical, emission, electrochemical and third-order nonlinear optical (NLO) properties were investigated. Soret band was broadened due to the presence of triphenylamine moiety. Electrochemical properties indicated that both oxidation and reduction processes were ring centered. Emission spectra were recorded in different solvents and the fluorescence yields obtained were in the range of 0.02–0.17 while the time-resolved fluorescence data revealed radiative lifetimes of typically few ns. Third-order NLO properties of this molecule have been examined using the Z-scan technique with picosecond (ps) and femtoseocnd (fs) pulses. Closed and open aperture Z-scan data were recorded with 2 ps/1 50 fs laser pulses at a wavelength of 800 nm and NLO coefficients were extracted from both the data. Our data clearly suggests the potential of this molecule for photonics applications.

NIR and Upconversion Luminescence Properties of Nd3+ Doped in Gd2O3-CaO-SiO2-B2O3 Glass System

2014 ◽  
Vol 548-549 ◽  
pp. 124-128 ◽  
Author(s):  
S. Insiripong ◽  
S. Kaewjeang ◽  
U. Maghanemi ◽  
H.J. Kim ◽  
N. Chanthima ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Upconversion Luminescence ◽  
Emission Spectra ◽  
Concentration Quenching ◽  
Luminescence Spectra ◽  
Optical Absorption Spectra ◽  
Glass Matrices ◽  
Nir Luminescence

In this work, properties of Nd3+ in Gd2O3-CaO-SiO2-B2O3 glass systems with composition 25Gd2O3-10CaO-10SiO2-(55-x)B2O3-xNd2O3 where x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol% were investigated. The optical absorption spectra show peaks at 4F3/2 (877 nm) , 4F5/2+2H9/2 (802 nm), 4F7/2+4S3/2 (743 nm), 4F9/2 (682 nm), 2H11/2 (627 nm), 2G7/2 +4G5/2 (582 nm), 4G7/2 +2K13/2 (527 nm), 4G11/2 (481 nm), 2P1/2 (427 nm) and 2L15/2 + 4D1/2 + 1I11/2+ 4D5/2+ 4D3/2 (355 nm) reflecting the Nd3+ ions in glass matrices. The densities were increased with increasing of Nd2O3 concentration. This indicates the increase of the molecular weight by the replacement of B2O3 with a heavier Nd2O3 oxide in the glass. The upconversion luminescence spectra show bands at 393 nm for all Nd2O3 concentration and the strongest intensity from 2.5 % mol of Nd2O3 was obtained. For NIR luminescence, the intensity of Nd3+ emission spectra increases with increasing concentrations of Nd3+ up to 1.5 mol% and beyond 1.5 mol% the concentration quenching is observed.

Preparation and Properties of La2O3-CaO-P2O5 Glasses Doped with Eu3+ Ions

2016 ◽  
Vol 675-676 ◽  
pp. 376-379 ◽  
Author(s):  
Narun Luewarasirikul ◽  
Piyachat Meejitpaisan ◽  
Jakrapong Kaewkhao
Keyword(s):  
Calcium Phosphate ◽  
Molar Volume ◽  
Absorption Spectra ◽  
Room Temperature ◽  
Emission Spectra ◽  
Phosphate Glasses ◽  
Excitation Wavelength ◽  
Melt Quenching ◽  
Volume Measurements ◽  
Doped Glasses

Lanthanum calcium phosphate glasses doped with Eu3+ ions in compositions 20La2O3:10CaO:(70-x)P2O5:xEu2O3 (where x = 0.05, 0.10, 0.50 and 1.50 mol%) were prepared by melt-quenching technique. The density and molar volume measurements were carried out at room temperature. The absorption spectra were investigated in the UV-Vis-NIR region from 200 to 2500 nm. The emission spectra of Eu3+-doped glasses centered at 590 nm (5D0→7F1), 612 nm (5D0→7F2), 652 nm (5D0→7F3) and 699 nm (5D0→7F4) have been observed with 393 nm excitation wavelength.

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