Semiconductor electrodes. 50. Effect of mode of illumination and doping on photochemical behavior of phthalocyanine films

KAZUHIKO TAKEDA, YUTAKA HARIMA, and K~z u o YAMASHITA. Can. J. Chem. 69, 192 (1991). Photoresponses for various porphyrin films prepared by the electrolytic micelle disruption (EMD) method have been investigated in the indium-tin oxide/porphyrin/I;, I-/Pt cell. The EMD film of an n-type porphyrin, 5,10,15,20-tetra(4-pyridy1)porphyrin (T(4-Py)P), exhibited a clear optical filtering effect (OFE), while not for the EMD films of p-type porphyrins such as (5,10,15,20-tetraphenylporphyrinato)zinc(II) (ZnTPP). For the EMD-ZnTPP film, the photocurrents at 500-700 nm were remarkably enhanced by increasing the film thickness. These photoelectrochemical properties were explained in terms of the electrolyte-permeability of the EMD films, which were confirmed by the electrochemical measurements and electron microscopic observations. The high conversion efficiency of the EMD-ZnTPP film was explained on the same basis. The difference in the thickness dependence of OFE between T(4-Py)P films prepared by the EMD and physical vapor deposition method was elucidated by the differences in diffusion lengths of excitons and in widths of photoactive layers in the films. In addition, a modified version of the EMD method was described in conjunction with a morphology control of the porphyrin solids.

Section: Resultsmentioning

confidence: 99%

Photoelectrochemical and optical properties of porphyrin thin films prepared by the electrolytic micelle disruption method

Takeda¹,

Harima²,

Yamashita³

1991

“…Le potentiel de bande plate varie beaucoup avec le pH de la solution dans le cas du couple rtdox BQ/HQ, alors qu'il a Ct C trouvC indCpendant du pH dans le cas du couple rCdox 13-/Ip. Un comportement identique a CtC observC (20) entre H2Pc et le chloranil; il augmente la conductivite dans le noir et la photoconductivitC du pigment (14,41,42). La benzoquinone est un accepteur plus faible que le chloranil, mais un complexe a 1'Ctat fondamental a CtC rapport6 dans I'acktone entre BQ et des tCtratolylporphines libres et de zinc (43), qui sont des molCcules tres proches de PcAlOH.…”

Section: Courbes Courant-tensionunclassified

“…Des progres remarquables ont CtC rCalisCs dans l'augmentation de I'efficacitC de conversion des cellules photovoltai'ques organiques, passant de au debut des annCes 1970 1% actuellement (3). Les composCs de type phtalocyanine ont r e p une attention particuliere en tant que colorants pour la sensibilisation spectrale et la stabilisation de semiconducteurs inorganiques (4)(5)(6)(7)(8)(9) et en tant que semiconducteurs formant des jonctions liquides avec des couples redox (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25).…”

Section: Introductionunclassified

“…La sublimation est la technique de deposition la plus frequemment utilisCe pour la fabrication de films de phtalocyanines (10)(11)(12)(13)(14)(15)(16)(17)(18)(19), mais on retrouve aussi 1'ClectrodCposition (20) et la dCposition par monocouches (32,33). Les phtalocyanines peuvent Etre aussi dispersees dans un polymere et le mClange obtenu peut Etre CtalC en films minces a l'aide d'un couteau ou d'un rouleau (23,24), ou dCposC par rotation (27,34) sur un support transparent.…”

Section: Introductionunclassified

See 1 more Smart Citation

Cellules photoélectrochimiques de phtalocyanine d'hydroxyaluminium déposées par rotation

Perrier¹,

Dao²

1986

“…Des Ctudes Clectrochirniques et photoClectrochimiques mettant en cause des Clectrodes de quelques phtalocyanines (H2Pc, ZnPc, FePc, CuPc, NiPc) en couches minces ont Cgalernent CtC rapportCes (17,18). De plus, des films de phtalocyanines ont CtC utilisCs pour de la sensibilisation spectrale dans des cellules photoClectrochimiques (19)(20)(21)(22)(23).…”

Section: Introductionunclassified

Photoélectrochimie des phtalocyanines sans métal, de cuivre et de fer

Marsan¹,

Bélanger²,

Piron³

1985

The cathodic and photocathodic behavior of electrodes of phthalocyanines without metal or complexed to copper or iron (H2Pc, CuPc, and FePc) has been studied in acidic, neutral, and alkaline media. In the dark, the polarization curve of the electrode of FePc shows two peaks of reduction which are not observed with the other phthalocyanines; these are associated with the reduction of the central cation. Lighting the semiconducting electrodes does not produce any effect on the reaction of production of hydrogen. An analysis of the curves of capacity vs. potential indicates the presence of intermediate levels localized within the forbidden band of the semiconductors and covering about 1% of their sites on the surface. The results can be explained if the phthalocyanines are considered to be semiconducting electrodes of type p. The energy of the bands and of the surface states can be depicted with a semiconductor–electrolyte interphase model and the nature of the charge transfers inhibited by the presence of these interfacial states is discussed. [Journal translation]