NSLS-II Seminar

Conjugated, semi-conducting polymers have tremendous potential for use in cheap, flexible, light weight devices and have been widely studied in thin film transistors (TFTs), light emitting diodes (LEDs), and photovoltaics (OPVs). Such devices offer the potential to create cheap energy, consume less energy, or be simply cheaper and more practical. Despite great empirical advances during the recent past and a rapidly growing research community, fundamental understanding of device function is still lacking in many instances. The relationship, for example, between structure, processing, and device performance is still unclear in poly(2,5-bis(3-tetradecyllthiophen-2-yl)thieno[3,2-b]thiophene) (pBTTT) based TFT devices. Recent work at the Advanced Light Source has for the first time uncovered a fundamental relationship between the length-scale of the correlation of the polymer backbone orientation as measured with resonant scattering and the saturation mobility. I will discuss these results and a number of other important issues in organic devices that could be resolved. I furthermore delineate important questions that are raised by the soft x-ray experiments. The examples discussed exemplify the importance of the mesoscale structure, i.e. how the nano-scale is connected to the “real world”. The advanced characterization capabilities anticipated to be available at NSLS-II should further accelerate progress and understanding in this rapidly growing field.