title: Photostability Can Be Significantly Modulated by Molecular Packing in Glasses.
abstract: While previous work has demonstrated that molecular packing in organic crystals can strongly influence photochemical stability, efforts to tune photostability in amorphous materials have shown much smaller effects. Here we show that physical vapor deposition can substantially improve the photostability of organic glasses. Disperse Orange 37 (DO37), an azobenzene derivative, is studied as a model system. Photostability is assessed through changes in the density and molecular orientation of glassy thin films during light irradiation. By optimizing the substrate temperature used for deposition, we can increase photostability by a factor of 50 relative to the liquid-cooled glass. Photostability correlates with glass density, with density increases of up to 1.3%. Coarse-grained molecular simulations, which mimic glass preparation and the photoisomerization reaction, also indicate that glasses with higher density have substantially increased photostability. These results provide insights that may assist in the design of organic photovoltaics and light-emission devices with longer lifetimes.
authors: Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors: Yue
authors: Y
authors: Qiu
authors: Institute for Molecular Engineering, University of Chicago , Chicago, Illinois 60637, United States.
authors: Lucas W
authors: LW
authors: Antony
authors: Institute for Molecular Engineering, University of Chicago , Chicago, Illinois 60637, United States.
authors: Juan J
authors: JJ
authors: de Pablo
authors: Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors: M D
authors: MD
authors: Ediger