Quantitative estimation of the efficiency of electron injection from excited sensitizer dye into nanocrystalline ZnO film

The absolute value of the efficiency of electron injection from an excited coumarin dye (NKX-2311) into a nanocrystalline ZnO film was estimated as 0.8 +/- 0.1 through transient absorption measurements. This value was obtained by using the molar absorption coefficient of the oxidized form of NKX-2311 determined in solution. Using this value and the previously obtained relative injection efficiency, we estimated the molar absorption coefficients of the oxidized form of N3 dye (cis-bis(4,4'-dicarboxy-2,2'-bipyridine)dithiocyanato ruthenium(II); Ru(dcbpy)(2)(NCS)(2)) and the conducting electrons in the ZnO film.