Electromodulation and magnetomodulation of exciton dissociation in electron donor (starburst amine) : electron acceptor (bathocuproine) system

Pelczarski, Daniel; Grygiel, Piotr; Falkowski, Karol; Klein, Maciej; Stampor, Waldemar

doi:10.1016/j.orgel.2015.06.050

Cited by 10 publications

(10 citation statements)

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“…4 ) has been obtained for NP-B1 solar devices with the HWHM equal to B LFE = 55 mT and B HFE = 600 mT while for NP-SQ2 devices B LFE = 17 mT and B HFE = 400 mT. Note that the HWHM of the low field component is much broader than hyperfine field in the EHP model, which is typically ~3 mT in organic compounds 9 10 21 23 . Furthermore, the strong spin-orbit coupling in N719 and B1 dyes induced by the high orbital magnetic field of ruthenium atom switches off the hyperfine field-scale effects 18 23 , therefore, HFM spin-mixing mechanism is rather not appropriate here.…”

Section: Resultsmentioning

confidence: 92%

“…In the relevant components of the formula (2) representing the low-field (LFE) and high-field (HFE) effects A LFE and A HFE parameters denote the MPC signal magnitudes for , whereas B LFE and B HFE determine the half width (B 1/2 ) at half signal maximum (HWHM) 10 . The relatively good fitting based on double-Lorentzian function (solid lines in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…This primary charge separation step in DSSCs has been extensively studied by femtosecond transient absorption spectroscopy 5 6 7 , however, the exact nature of the spatial separation of charge carriers involving possibly an intermediate stage of geminate electron-hole (e-h) pairs or exiciplex states is not fully understood so far 7 8 . Nevertheless, if these intermediate species are endowed with the magnetic moment then a low external magnetic field of tens mT strength can interact with them and this way change the generated photocurrent as observed in tris-(8-hydroxyquinolinato) aluminum (III) (Alq 3 ) films 9 , starburst amine (m-MTDATA): bathocuproine (BCP) system 10 or in polyhexylthiophene (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells 11 12 . Therefore, near-unity quantum efficiency of organic solar cells is achieved not only due to efficient (e-h) pair dissociation by electric field but it arises through the interplay between spin, energetics and delocalization of electronic excitations in organic semiconductors 13 .…”

mentioning

confidence: 99%

“…Consequently, singlet becomes a triplet, and vice versa . According to Zeeman effect the low external magnetic field of a few militesla competes with the hyperfine field (hyperfine interaction modulation - HFM) and thus splits the triplet sublevels, T +1 and T −1 , leading to the suppression of ISC process between singlet and triplet polaron pairs 10 19 20 21 . However, at high magnetic field induction (typically of ca.…”

mentioning

confidence: 99%

“… 25 (see also ref. 10 and 26 ), respectively. Recently magnetic field effects have been also reported for various n-types of dye-sensitized solar cells 27 28 , however, the proposed mechanism of these effects is unclear.…”

mentioning

confidence: 99%

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Magnetic field effects in dye-sensitized solar cells controlled by different cell architecture

Klein

Pankiewicz

Zalas

et al. 2016

Sci Rep

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The charge recombination and exciton dissociation are generally recognized as the basic electronic processes limiting the efficiency of photovoltaic devices. In this work, we propose a detailed mechanism of photocurrent generation in dye-sensitized solar cells (DSSCs) examined by magnetic field effect (MFE) technique. Here we demonstrate that the magnitude of the MFE on photocurrent in DSSCs can be controlled by the radius and spin coherence time of electron-hole (e-h) pairs which are experimentally modified by the photoanode morphology (TiO2 nanoparticles or nanotubes) and the electronic orbital structure of various dye molecules (ruthenium N719, dinuclear ruthenium B1 and fully organic squaraine SQ2 dyes). The observed MFE is attributed to magnetic-field-induced spin-mixing of (e-h) pairs according to the Δg mechanism.

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