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In situ linear absorption and single-shot transient absorption are employed to understand how morphological changes during thermal annealing impact the electronic structure and excited-state dynamics of a polymer: fullerene blend. 

This study seeks to illuminate the aggregation and excited state dynamics of intercalated phthalocyanine:fullerene thin films during deposition viain situUV-vis spectroscopy and a spatially encoded transient absorption (TA) spectroscopy. 

A highly NIR-absorptive organic dye forms monomers when kinetically trapped in a polymer matrix, but upon thermal annealing, aggregation causes changes in excited-state processes, which are assayed via in situ transient absorption. 

A significant advantage of organic semiconductors over many of their inorganic counterparts is solution processability. However, solution processing commonly yields heterogeneous films with properties that are highly sensitive to the conditions and parameters of casting and processing. Measuring the key properties of these materials in situ, during film production, can provide new insight into the mechanism of these processing steps and how they lead to the emergence of the final organic film properties. The excited-state dynamics is often of import in photovoltaic, electronic, and light-emitting devices. This review focuses on single-shot transient absorption, which measures a transient spectrum in a single shot, enabling the rapid measurement of unstable chemical systems such as organic films during their casting and processing. We review the principles of instrument design and provide examples of the utility of this spectroscopy for measuring organic films during their production.