TY - JOUR
T1 - Near-Infrared Photoelectrochemical Conversion via Photoinduced Charge Separation in Supramolecular Complexes of Anionic Phthalocyanines with Li+@C60
AU - Kawashima, Yuki
AU - Ohkubo, Kei
AU - Blas-Ferrando, Vicente Manuel
AU - Sakai, Hayato
AU - Font-Sanchis, Enrique
AU - Ortíz, Javier
AU - Fernández-Lázaro, Fernando
AU - Hasobe, Taku
AU - Sastre-Santos, Ángela
AU - Fukuzumi, Shunichi
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/6/18
Y1 - 2015/6/18
N2 - Two phthalocyanines possessing carboxylate groups ((TBA)4 H2 Pc·1 and (TBA)4 H2 Pc·2) form 1:2 supramolecular complexes with lithium cation-encapsulated C60 (Li+@C60 ) [H2 Pc·14-/(Li+@C60 )2 and H2 Pc·24-/(Li+@C60 )2 ] in a polar mixed solvent. From the UV-vis spectral changes, the binding constants (K) were estimated as ca. 1012 M-2. Upon the photoexcitation of constructed supramolecular complexes, photoinduced electron transfer occurred to form the charge-separated (CS) state. The lifetime of the CS state was determined to be 1.2 ms for H2 Pc·24-/(Li+@C60 )2 , which is the longest CS lifetime among the porphyrinoid/fullerene supramolecular complexes. H2 Pc·14-/(Li+@C60 )2 also afforded the long-lived CS state of 1.0 ms. The spin state of the long-lived CS states was determined to be a triplet, as indicated by the EPR signal at g = 4. The reorganization energy (λ) and the electronic coupling term were determined to be λ = 1.70 eV, V = 0.15 cm-1 from the temperature dependence of the rate constant for the charge recombination of the CS state of H2 Pc·14-/(Li+@C60 )2 . The energy of the CS state (0.49 eV) is much smaller than the reorganization energy, indicating that the back-electron-transfer process is located in the Marcus normal region. The small electronic coupling term results from the spin-forbidden back electron transfer due to the triplet CS state. Supramolecular complexes of anionic zinc phthalocyanines with Li+@C60 were also prepared and investigated. The ZnPc·44-/Li+@C60 supramolecular nanoclusters were assembled on the optically transparent electrode (OTE) of nanostructured SnO2 (OTE/SnO2 ) to construct the dye-sensitized solar cell. The IPCE (incident photon-to-photocurrent efficiency) values of OTE/SnO2 /(ZnPc·44-/Li+@C60 )n were much higher than the sum of the two IPCE values of the individual systems OTE/SnO2 /(Li+@C60 )n and OTE/SnO2 /(ZnPc·44-)n , covering the near-infrared region.
AB - Two phthalocyanines possessing carboxylate groups ((TBA)4 H2 Pc·1 and (TBA)4 H2 Pc·2) form 1:2 supramolecular complexes with lithium cation-encapsulated C60 (Li+@C60 ) [H2 Pc·14-/(Li+@C60 )2 and H2 Pc·24-/(Li+@C60 )2 ] in a polar mixed solvent. From the UV-vis spectral changes, the binding constants (K) were estimated as ca. 1012 M-2. Upon the photoexcitation of constructed supramolecular complexes, photoinduced electron transfer occurred to form the charge-separated (CS) state. The lifetime of the CS state was determined to be 1.2 ms for H2 Pc·24-/(Li+@C60 )2 , which is the longest CS lifetime among the porphyrinoid/fullerene supramolecular complexes. H2 Pc·14-/(Li+@C60 )2 also afforded the long-lived CS state of 1.0 ms. The spin state of the long-lived CS states was determined to be a triplet, as indicated by the EPR signal at g = 4. The reorganization energy (λ) and the electronic coupling term were determined to be λ = 1.70 eV, V = 0.15 cm-1 from the temperature dependence of the rate constant for the charge recombination of the CS state of H2 Pc·14-/(Li+@C60 )2 . The energy of the CS state (0.49 eV) is much smaller than the reorganization energy, indicating that the back-electron-transfer process is located in the Marcus normal region. The small electronic coupling term results from the spin-forbidden back electron transfer due to the triplet CS state. Supramolecular complexes of anionic zinc phthalocyanines with Li+@C60 were also prepared and investigated. The ZnPc·44-/Li+@C60 supramolecular nanoclusters were assembled on the optically transparent electrode (OTE) of nanostructured SnO2 (OTE/SnO2 ) to construct the dye-sensitized solar cell. The IPCE (incident photon-to-photocurrent efficiency) values of OTE/SnO2 /(ZnPc·44-/Li+@C60 )n were much higher than the sum of the two IPCE values of the individual systems OTE/SnO2 /(Li+@C60 )n and OTE/SnO2 /(ZnPc·44-)n , covering the near-infrared region.
UR - http://www.scopus.com/inward/record.url?scp=84934963413&partnerID=8YFLogxK
U2 - 10.1021/jp5123163
DO - 10.1021/jp5123163
M3 - Article
C2 - 25615010
AN - SCOPUS:84934963413
SN - 1520-6106
VL - 119
SP - 7690
EP - 7697
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 24
ER -