Exciton Dynamics of P3HT:PCBM Blend Films with Different Polymer Regioregularities Using Transient Absorption Spectroscopy

Lee, Sunae; Lee, Myoung-Hee; An, Jongdeok; Ahme, Helene; Im, Chan

doi:10.1080/15421406.2013.804381

Cited by 6 publications

(7 citation statements)

References 14 publications

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“…Such a decrease of all the time constants supports the occurrence of the intermolecular charge transfer between ABSQs and PCBM. 58 The occurrence of the charge-transfer dynamics is further confirmed by the formation of radical cations of squaraine derivatives exhibiting positive transient absorption at around 710 nm, consistent with the literature, 25,53,54 upon addition of PCBM at a longer time delay (Figure S14). However, the transient absorption spectra showing the anion radical of PCBM in the NIR region 59,60 would be advantageous to support the occurrence of the intermolecular charge-transfer process in the mixture.…”

Section: ■ Results and Discussionsupporting

confidence: 87%

“…Importantly, the decrease of τ 3 for all the derivatives is consistent with the reduction of fluorescence dynamics observed in the TCSPC. Such a decrease of all the time constants supports the occurrence of the intermolecular charge transfer between ABSQs and PCBM . The occurrence of the charge-transfer dynamics is further confirmed by the formation of radical cations of squaraine derivatives exhibiting positive transient absorption at around 710 nm, consistent with the literature, ,, upon addition of PCBM at a longer time delay (Figure S14).…”

Section: Resultssupporting

confidence: 86%

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Ultrafast Intermolecular Interaction Dynamics between NIR-Absorbing Unsymmetrical Squaraines and PCBM: Effects of Halogen Substitution

et al. 2022

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Among near-infrared (NIR) dyes, squaraine derivatives are applied as efficient sensitizers in optoelectronic and biomedical devices due to their simple synthesis, intense absorption, and emission and exceptional photochemical stability. The fundamental understanding of the structure–property relationships of sensitizers provides the insight to increase the efficiency of such devices. Here, unsymmetrical squaraine derivatives (ABSQs) with donor–acceptor–donor (D–A–D′) architectures having N,N-dimethyl amino anthracene and benzothiazole (ABSQ-H) halogenated with fluoride (ABSQ-F), chloride (ABSQ-Cl), and bromide (ABSQ-Br) were synthesized to understand the effect of halogen on the photophysical properties and intermolecular interaction dynamics with phenyl-C61-butyric acid methyl ester (PCBM), which is used widely as an electron acceptor in bulk heterojunction-based devices. Interestingly, ABSQ-H exhibited intense absorption (ε ∼ 6.72 × 104 M–1 cm–1) spectra centered at ∼660 nm. Upon halogen substitution, a bathochromic shift in the absorption spectra with an increase of molar absorptivity was observed (ε ∼ 8.59 × 104 M–1 cm–1), which is beneficial for NIR light harvesting. The femtosecond transient absorption spectra of ABSQs revealed that the polarity of the solvent controlled the excited-state relaxation dynamics. Upon addition of PCBM, the fluorescence intensity and dynamics of halogenated ABSQs were quenched, and the formation of a squaraine radical cation was observed, reflecting the occurrence of intermolecular charge-transfer dynamics between ABSQs and PCBM. Thus, the observation of a bathochromic shift with intense absorption and an efficient intermolecular interaction with PCBM upon halogenation of ABSQs provide a design strategy for the development of unsymmetrical squaraine derivatives for bulk heterojunction-based optoelectronic devices.

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Section: ■ Results and Discussionsupporting

confidence: 87%

Section: Resultssupporting

confidence: 86%

Ultrafast Intermolecular Interaction Dynamics between NIR-Absorbing Unsymmetrical Squaraines and PCBM: Effects of Halogen Substitution

et al. 2022

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“…On the one hand, it was reported that charge transfer (CT) efficiency at the P3HT/PCBM interface does not depend on specific regularity of P3HT chains, whereas charge dissociation is better for regioregular P3HT chains . On the other hand, it was shown recently that the use of regiorandom instead of regioregular P3HT leads to more effective electron transfer from P3HT to PCBM, which means that disorder can facilitate CT processes . This suggestion was also supported earlier by theoretical models. , While it is well-known that structural and energetic disorder normally suppresses CT along the polymer chain, − the effect of chain disorder on electron transfer from donor to acceptor moiety has not been studied thoroughly, and to our knowledge only few experimental − and theoretical , works dealt with this problem.…”

Section: Introductionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Effect of the Polymer Chain Arrangement on Exciton and Polaron Dynamics in P3HT and P3HT:PCBM Films

et al. 2018

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Arrangement of polymer chains at the interface with an acceptor is one of the key issues which influences the interfacial charge transfer. Films of P3HT and P3HT:PCBM blends with the different polymer chain arrangement have been prepared from one-component and binary solvents representing a mixture of chloroform and different poor solvents with high boiling temperature. Electronic absorption and photoluminescence spectra evidenced in favor of reduced disorder of P3HT films as a result of use of poor solvents; the ordering was displayed through structuring and narrowing the spectral bands, indicative of decreasing width of Gaussian distribution of molecular transition frequencies. At the same time, transient absorption of singlet excitons showed that exciton decay in highly ordered P3HT films slows down as compared to the disordered film, and this effect was reproduced for the different poor solvents used. A more pronounced effect was revealed in P3HT:PCBM blends where much faster decay of excitons was found in disordered as-prepared P3HT:PCBM film from chloroform as compared to the annealed film or films prepared from the binary solvents. A complex behavior of polarons in the different regions of the blend film, i.e., within crystalline domains of P3HT and at the interface of P3HT/PCBM, was observed. The conclusion was drawn that chain disorder induces easier exciton dissociation and charge transfer at the P3HT/PCBM interface.

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“…In some works the triplet state [14] formation is studied [7,[15][16][17][18]. Ultrafast transient absorption spectroscopy also allows to observe exciton dynamics in polymer/fullerene blends [19,20].…”

Section: Introductionmentioning

confidence: 99%

Photochemistry of P3HT and PC 60 BM in toluene solution: Evidence of T–T energy transfer

Lukina

Pozdnyakov

Mereshchenko

et al. 2015

Journal of Photochemistry and Photobiology A: Chemistry

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A B S T R A C TPhotochemical properties of regioregular poly(3-hexylthiophene) (P3HT), fullerene derivative [6,6]-phenyl C61-butyric acid methyl ester (PC 60 BM) and their 1:1 mixture in argon-saturated toluene solution were studied by optical spectroscopy and nanosecond laser flash photolysis (l ex = 532 nm). Separate excitation of components leads to formation of corresponding triplet state of fullerene (

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Exciton Dynamics of P3HT:PCBM Blend Films with Different Polymer Regioregularities Using Transient Absorption Spectroscopy

Cited by 6 publications

References 14 publications

Ultrafast Intermolecular Interaction Dynamics between NIR-Absorbing Unsymmetrical Squaraines and PCBM: Effects of Halogen Substitution

Ultrafast Intermolecular Interaction Dynamics between NIR-Absorbing Unsymmetrical Squaraines and PCBM: Effects of Halogen Substitution

Effect of the Polymer Chain Arrangement on Exciton and Polaron Dynamics in P3HT and P3HT:PCBM Films

Photochemistry of P3HT and PC 60 BM in toluene solution: Evidence of T–T energy transfer

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