Sadaharu Suga

Design of new coumarin dyes having thiophene moieties for highly efficient organic-dye-sensitized solar cells

We have developed new coumarin dyes having thiophene moieties in order to improve the photovoltaic performance of dye-sensitized nanocrystalline TiO2 solar cells based on the organic dyes as photosensitizers. A solar-energy-to-electricity conversion efficiency (η) of 7.7% was attained under AM 1.5 irradiation (100 mW cm−2) with a short-circuit current density (Jsc) of 14.3 mA cm−2, an open-circuit voltage (Voc) of 0.73 V, and a fill factor (ff) of 0.74.

A coumarin-derivative dye sensitized nanocrystalline TiO2 solar cell having a high solar-energy conversion efficiency up to 5.6%

It is found that newly synthesized coumarin derivatives work as highly efficient photosensitizers for dye-sensitized nanocrystalline TiO2 solar cells producing a 5.6% solar-light-to-electricity conversion efficiency, the highest efficiency so far among organic dye-sensitized solar cells, with a short-circuit current density of 13.8 mA cm−2, an open-circuit photovoltage of 0.63 V, and a fill factor of 0.63 under standard AM 1.5 irradiation (100 mW cm−2).

PHOTOSENSITIZATION OF A POROUS TIO2 ELECTRODE WITH MEROCYANINE DYES CONTAINING A CARBOXYL GROUP AND A LONG ALKYL CHAIN

Porous TiO2 electrodes sensitized using merocyanine dyes containing a carboxyl group and a long alkyl chain, in particular 3-carboxymethyl-5-[2-(3-alkyl-2-benzothiazoli- nyldene)ethylidene]-2-thioxo-4-thiazolidinone, showed remarkably high solar–energy efficiency (4.2%, AM-1.5, 100 mW cm−2).

Novel polyene dyes for highly efficient dye-sensitized solar cells.

We have developed an efficient and novel polyene-dye-sensitized nanocrystalline TiO2 solar cells producing a 6.8% solar energy-to-electricity conversion efficiency (eta) under AM 1.5 irradiation (100 mW cm(-2)): short-circuit current density (Jsc), 12.9 mA cm(-2), open-circuit photovoltage (Voc), 0.71 V, fill factor (ff), 0.74.

Significant effects of the distance between the cyanine dye skeleton and the semiconductor surface on the photoelectrochemical properties of dye-sensitized porous semiconductor electrodes

The incident photon-to-current conversion efficiency (IPCE) of a porous TiO2 electrode sensitized by cyanine dyes increased with decreasing distance between the skeleton of the dye and the TiO2 surface. The photocurrent of oxide semiconductor electrodes sensitized by a cyanine dye increased with the positive shift of the conduction band potential of the oxide semiconductor in the following order: Nb2O5<TiO2<ZnO<SnO2. The SnO2 semiconductor cell showed the best light-to-electric conversion efficiency among the four semiconductors.