Premium
Relationship between dye–iodine binding and cell voltage in dye‐sensitized solar cells: A quantum‐mechanical look
Author(s) -
Asaduzzaman Abu Md.,
Chappellaz Guy A. G.,
Schreckenbach Georg
Publication year - 2012
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.23070
Subject(s) - bromine , iodine , chemistry , chalcogen , photochemistry , steric effects , solar cell , redox , oxygen , binding energy , inorganic chemistry , stereochemistry , organic chemistry , materials science , physics , optoelectronics , nuclear physics
It has been proposed that iodine binding to dyes may actually decrease the cell efficiency of a dye‐sensitized solar cell. A previous experimental study showed that a two‐atom change from oxygen to sulfur increased recombination of iodine with injected electrons by a factor of approximately 2. Here, it is shown that iodine binding is a plausible explanation for this effect. The steric and conjugation effects are quantified separately using a set of model compounds. Quantum‐chemical calculations show that elongation of the hydrocarbon chain has only an insignificant effect on the iodine and bromine binding to the chalcogen atoms (O, S, Se). The conjugation, however, significantly disfavors the iodine and bromine interaction. Iodine and bromine binding to the dye and model compounds containing sulfur is significantly more favorable than to their oxygen containing counterparts. Bromine binding to dyes is shown to be stronger than that of iodine. Accordingly, bromine binding to dyes may contribute significantly to the observed lower efficiencies in cells using Br 3 − /Br − as the redox couple. © 2012 Wiley Periodicals, Inc.