Nonlinear Optical and Transport Properties of Fullerene Crystals

1994 ◽  
Vol 359 ◽  
Author(s):  
Hugh J. Byrne ◽  
Lidia Akselrod ◽  
Andreas T. Werner ◽  
Wolfgang K. Maser ◽  
Mathias Kaiser ◽  
...  
Keyword(s):  
Phase Transition ◽  
Excited State ◽  
Nonlinear Dependence ◽  
High Excited State ◽  
Time Resolved ◽  
Highly Nonlinear ◽  
Observed Behaviour ◽  
State Densities ◽  
Photochemical Modification ◽  
Time Resolved Photoluminescence

ABSTRACTPicosecond time resolved photoluminescence and photoconductivity measurements are performed to investigate the influence of high intensity illumination on the properties of Fullerene crystals. A highly nonlinear dependence of both the photoluminescence characteristics and the photoconductive response of the fullerenes is seen and temperature dependent measurements indicate that the nonlinear processes are associated with an insulatormetal-like phase transition in the material, and thus that the electronic properties of the excited state are dramatically altered at high excited state densities. The observed behaviour is compared and contrasted to the changes in the optical properties upon photochemical modification of the pristine material via Raman spectroscopy. Application of a simple phenomenological model to calculate the contribution of intermolecular exchange and correlation energies in the excited state supports the proposal that the observed phenomena originate from a Mott-like phase transition. A further manifestation of this behaviour is the emergence of a broadband electroluminescent emission above a critical injection current density.

Tuning the excited-state deactivation pathways of dinuclear ruthenium(ii) 2,2′-bipyridine complexes through bridging ligand design

2020 ◽  
Vol 49 (24) ◽  
pp. 8096-8106 ◽  
Author(s):  
Simon Cerfontaine ◽  
Ludovic Troian-Gautier ◽  
Sara A. M. Wehlin ◽  
Frédérique Loiseau ◽  
Emilie Cauët ◽  
...  
Keyword(s):  
Excited State ◽  
Steady State ◽  
Variable Temperature ◽  
Ligand Design ◽  
Binuclear Complexes ◽  
Time Resolved ◽  
Bridging Ligand ◽  
Dinuclear Ruthenium ◽  
Photophysical Study ◽  
Time Resolved Photoluminescence

A detailed photophysical study of binuclear complexes was performed using steady-state and time-resolved photoluminescence measurements at variable temperature. The results were compared with the prototypical [Ru(bpy)3]2+.

Time-resolved photoluminescence and excited state structure of Bi3+ center in YAlO3

2014 ◽  
Vol 36 (10) ◽  
pp. 1705-1708 ◽  
Author(s):  
A. Krasnikov ◽  
L. Lipińska ◽  
E. Mihokova ◽  
M. Nikl ◽  
T. Shalapska ◽  
...  
Keyword(s):  
Excited State ◽  
State Structure ◽  
Time Resolved ◽  
Time Resolved Photoluminescence

scholarly journals Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3904
Author(s):  
Kaveendra Maduwantha ◽  
Shigeyuki Yamada ◽  
Kaveenga Rasika Koswattage ◽  
Tsutomu Konno ◽  
Takuya Hosokai
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Density Functional Theory Calculations ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Unique Material ◽  
Potential Applications ◽  
Time Resolved Photoluminescence

Room-temperature phosphorescent (RTP) materials have been attracting tremendous interest, owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we reported the synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al., Beilstein J. Org. Chem. 2020, 16, 1154–1162.]. To deeply understand their RTP properties, we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra, measured at 77 K, and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. The correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is discussed.

Quantification of trap state densities in GaAs heterostructures grown at varying rates using intensity-dependent time resolved photoluminescence

2013 ◽  
Vol 102 (18) ◽  
pp. 182108 ◽  
Author(s):  
C. R. Haughn ◽  
K. J. Schmieder ◽  
J. M. O. Zide ◽  
A. Barnett ◽  
C. Ebert ◽  
...  
Keyword(s):  
Trap State ◽  
Time Resolved ◽  
State Densities ◽  
Time Resolved Photoluminescence

scholarly journals Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks

2020 ◽  
Author(s):  
Kaveendra Maduwantha ◽  
Shigeyuki Yamada ◽  
Kaveenga Rasika Koswattage ◽  
Tsutomu Konno ◽  
Takuya Hosokai
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Density Functional Theory Calculations ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Unique Material ◽  
Potential Applications ◽  
Time Resolved Photoluminescence

Room-temperature phosphorescent (RTP) materials have been attracted tremendous interest owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we have reported a synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al, Beilstein J. Org. Chem. 2020, 16, 1154–1162.]. To further understand their RTP properties, here we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra measured at 77 K and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. A discussion of the correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is presented.

Time resolved photoluminescence spectra of PPV film: heterogeneity and excited state relaxation

2004 ◽  
Vol 386 (1-3) ◽  
pp. 118-122 ◽  
Author(s):  
V.V.N. Ravi Kishore ◽  
Sonali Kokane ◽  
K.L. Narasimhan ◽  
N. Periasamy
Keyword(s):  
Excited State ◽  
Photoluminescence Spectra ◽  
Time Resolved ◽  
Time Resolved Photoluminescence

scholarly journals Excited State Dynamics of Perylenediimide films with Isopropyl phenyl- and Undecane-Substitution

2020 ◽  
Author(s):  
Qiu-Shi Ma ◽  
Cheng-Wei Ju ◽  
Ruihua Pu ◽  
Wenjie Zhang ◽  
Xian Lin ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Transient Absorption ◽  
Amorphous Film ◽  
Singlet Fission ◽  
Amorphous Films ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Coating Method ◽  
Time Resolved Photoluminescence

<p>The aggregation of Perylene Diimide (PDI) and its derivatives strongly depends on the molecular structure, and therefore has great impact on the excited states. By regulating the molecular stacking such as monomer, dimer, J- and/or H-aggregate, the formation of different excited states is adjustable and controllable. In this study, we have synthesized two kinds of PDI derivatives - undecane-substituted PDI (PDI-1) and diisopropylphenyl-substituted PDI (PDI-2), and the films are fabricated with spin-coating method. By employing photoluminescence (PL), time-resolved photoluminescence (TRPL) and transient absorption (TA) spectroscopy, the excited-state dynamics of two PDI amorphous films have been investigated systematically. The result reveals that both films have formed excimer after photoexcitation mainly due to the stronger electronic coupling among molecule aggregate in the amorphous film. It should be noted that the excited state dynamics in PDI-2 shows a singlet fission like process, which is evidenced by the appearance of triplet state absorption. This study provides the dynamics of excited state in amorphous PDI films, and pave the way for better understanding and adjusting the excited state of amorphous films. </p>

Excited State Dynamics of Perylenediimide films with Isopropyl phenyl- and Undecane-Substitution

2020 ◽  
Author(s):  
Qiu-Shi Ma ◽  
Cheng-Wei Ju ◽  
Ruihua Pu ◽  
Wenjie Zhang ◽  
Xian Lin ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Transient Absorption ◽  
Amorphous Film ◽  
Singlet Fission ◽  
Amorphous Films ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Coating Method ◽  
Time Resolved Photoluminescence

<p>The aggregation of Perylene Diimide (PDI) and its derivatives strongly depends on the molecular structure, and therefore has great impact on the excited states. By regulating the molecular stacking such as monomer, dimer, J- and/or H-aggregate, the formation of different excited states is adjustable and controllable. In this study, we have synthesized two kinds of PDI derivatives - undecane-substituted PDI (PDI-1) and diisopropylphenyl-substituted PDI (PDI-2), and the films are fabricated with spin-coating method. By employing photoluminescence (PL), time-resolved photoluminescence (TRPL) and transient absorption (TA) spectroscopy, the excited-state dynamics of two PDI amorphous films have been investigated systematically. The result reveals that both films have formed excimer after photoexcitation mainly due to the stronger electronic coupling among molecule aggregate in the amorphous film. It should be noted that the excited state dynamics in PDI-2 shows a singlet fission like process, which is evidenced by the appearance of triplet state absorption. This study provides the dynamics of excited state in amorphous PDI films, and pave the way for better understanding and adjusting the excited state of amorphous films. </p>

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