Chirp-independent time-resolved spectroscopy using the self-reference method

Kim, In-Sik; Sohn, Byoung-Uk; Hwang, Sung In; Lee, Chang‐Lyoul; Ko, Do‐Kyeong

doi:10.1088/1054-660x/24/4/045701

Cited by 10 publications

(11 citation statements)

References 19 publications

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“…The ground state absorptions were measured using an UV–vis absorption spectrometer (UV‐2450, Shimadzu). The excited state dynamics were determined with a TA spectrometer that was made in‐house, employing a femtosecond regenerative amplification system (Legend Elite Duo, Coherent, 800 nm, 1 kHz, 45 fs) . The fundamental beam was wavelength‐tailored for the pump and probe beams by second harmonic and white light continuum generations, respectively.…”

Section: Methodsmentioning

confidence: 99%

Effect of Fluorine Substitution on the Charge Carrier Dynamics of Benzothiadiazole‐Based Solar Cell Materials

Kim

et al. 2016

Macromol. Rapid Commun.

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The femtosecond transient absorption (TA) characterization of a new benzothiadiazole (BT)-based donor-acceptor conjugated copolymer, poly[(2,6-dithieno[3,2-b:2',3'-d]thiophene)-alt-(4,7-di(4-octyldodecylthiopen-2-yl)-2,1,3-benzo[c][1,2,5]thiadiazole (PBT), as well as its fluorinated derivatives, PFBT and PDFBT, is carried out. Additionally, bulk heterojunction (BHJ) films consisting of the copolymers and [6,6]-phenyl-C71 -butylic acid methyl ester (PC70 BM) are examined using TA spectroscopy. Both the singlet excited state dynamics in the copolymers and the charge transfer state dynamics in the BHJs are investigated in terms of fluorination dependency; the fluorinated copolymers exhibit less singlet exciton recombination rate than the fluorine-free copolymer, and the BHJs including the fluorinated copolymers display slower monomolecular recombination than the fluorine-free analogue. Furthermore, the excitation-intensity-dependent TA dynamics of the copolymers and BHJs is investigated, revealing that, when sufficiently high excitation intensity is used to induce annihilation processes, the fluorinated copolymers and BHJs incorporating the fluorinated copolymers show more rapid TA decay ascribable to morphological enhancement. These TA spectroscopic findings are found to correlate with the device characteristics with respect to fluorinated content in the polymer solar cells. In particular, both the short-circuit current density and fill factor of BHJ solar cells correspond closely with the fast decay parameters of the BHJ films under high excitation intensity.

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Section: Methodsmentioning

confidence: 99%

Effect of Fluorine Substitution on the Charge Carrier Dynamics of Benzothiadiazole‐Based Solar Cell Materials

Kim

et al. 2016

Macromol. Rapid Commun.

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“…The steady state absorption measurement was achieved by using a spectrometer (V-570, JASCO). The time-resolved measurements were measured with a home-built femtosecond transient absorption (TA) spectrometer applying second harmonic of main beam (800 nm, 45 fs, 1 kHz) as pump and a white light continuum as probe, and a methodological explanation is specified elsewhere [12]. The polarizations of pump and probe were tuned to be a magic angle (54.7°).…”

Section: Methodsmentioning

confidence: 99%

Femtosecond transient absorption dynamics in low bandgap polymer solar cell materials including poly(thienylenevinylene) derivative and benzothiadiazole moiety

et al. 2015

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“…The TA spectrometer setup is briefly explained in the Supporting Information and depicted elsewhere 19 .…”

Section: Introductionmentioning

confidence: 99%

Fabrication-Method-Dependent Excited State Dynamics in CH3NH3PbI3 Perovskite Films

Kim

Kang

et al. 2017

Sci Rep

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Understanding the excited-state dynamics in perovskite photovoltaics is necessary for progress in these materials, but changes in dynamics depending on the fabrication processes used for perovskite photoactive layers remain poorly characterised. Here we report a comparative study on femtosecond transient absorption (TA) in CH3NH3PbI3 perovskite films fabricated by various solution-processing methods. The grain sizes and the number of voids between grains on each film varied according to the film synthesis method. At the low excitation fluence of 0.37 μJ cm−2, fast signal drops in TA dyanmics within 1.5 ps were observed in all perovskite films, but the signal drop magnitudes differed becuase of the variations in charge migration to trap states and band gap renormalisation. For high excitation fluences, the buil-up time of the TA signal was increased by the activated hot-phonon bottleneck, while the signal decay rate was accelerated by fluence-dependent high-order charge recombination. These fluence-dependent dynamics changed for different perovskite fabrication methords, indicating that the dynamics were affected by morphological features such as grain sizes and defects.

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Chirp-independent time-resolved spectroscopy using the self-reference method

Cited by 10 publications

References 19 publications

Effect of Fluorine Substitution on the Charge Carrier Dynamics of Benzothiadiazole‐Based Solar Cell Materials

Effect of Fluorine Substitution on the Charge Carrier Dynamics of Benzothiadiazole‐Based Solar Cell Materials

Femtosecond transient absorption dynamics in low bandgap polymer solar cell materials including poly(thienylenevinylene) derivative and benzothiadiazole moiety

Fabrication-Method-Dependent Excited State Dynamics in CH3NH3PbI3 Perovskite Films

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