Fast charge transfer across dissimilar organic-organic, organic-inorganic, and organic-metal oxide interfaces is critical for high photoconversion efficiency in thin film solar energy conversion platforms.  Charge transfer, charge separation, and charge collection all compete kinetically with detrimental relaxation and recombination processes.  However the rates of these interfacial processes are hard to predict and must be measured as novel chromophores and transparent conductive oxides (TCO) are developed.  Transmission transient absorbance spectroscopy has been used to examine the photochemical kinetics of multilayer films where molecule-molecule and molecule-substrate processes occur simultaneously, but this geometry does not afford the sensitivity necessary to probe sub-monolayer chromophore films where interface processes can be isolated.  In this work, transient absorbance spectroscopy in attenuated total reflectance geometry was used to monitor excited state kinetics of semiconducting nanocrystals and porphyrin-perylene diimide dyads on TCO substrates and on insulating substrates.  Differences in the chromophores' excited state decay rates and ground state recovery rates as a function of the underlying substrate were used to quantitatively compare the desired interfacial charge transfer processes to the competing relaxation processes.  The excited state kinetics were correlated to the chemical and physical properties of both the chromophores and the TCOs, providing chemical rationale for the design of future active layer/TCO interfaces with sufficiently fast charge collection rates.

Photochemistry of chromophore/transparent conductive oxide interfaces measured using transient absorbance spectroscopy in attenuated total reflectance geometry

246th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.