5 years ago

Using Heterodyne-Detected Electronic Sum Frequency Generation To Probe the Electronic Structure of Buried Interfaces

Using Heterodyne-Detected Electronic Sum Frequency Generation To Probe the Electronic Structure of Buried Interfaces
Benny A. Renard, Jon A. Bender, Daniel E. Cotton, Ravindra Pandey, Aaron P. Moon, Sean T. Roberts
Organic semiconductors (OSCs) are attractive optoelectronic materials due to their high extinction coefficients, processing advantages, and ability to display unique phenomena such as singlet exciton fission. However, employing OSCs as active electronic components remains challenging, as this necessitates forming junctions between OSCs and other materials. Such junctions can distort the OSC’s electronic properties, complicating the transfer of energy and charge across them. To investigate these junctions, our group has employed an interface-selective technique, electronic sum frequency generation spectroscopy (ESFG), yet one complication in applying ESFG to thin OSC films is they necessarily have two interfaces that can each produce signals. In a conventional ESFG measurement, information regarding the phase of the ESFG signal is lost. However, this information can be recovered with heterodyne detection (HD) techniques. Here, we present experiments and model calculations that illustrate some key advantages offered by HD-ESFG over conventional ESFG measurements for the study of OSC films. Specifically, we report HD-ESFG spectra of N,N′-dimethyl-3,4,9,10-perylenedicarboximide (C1-PDI) thin films that have been grown on SiO2. To implement these measurements, we have constructed an HD-ESFG spectrometer that uses common path optics to maintain a high degree of phase stability over multiple hours. We find that not only does HD-ESFG offer increased sensitivity to weak features in ESFG spectra, but the phase information included in these measurements aids in selectively isolating signals that arise from a specific film interface. Interestingly, we find that resonances in HD-ESFG spectra of C1-PDI are significantly shifted from those in linear absorption spectra of bulk C1-PDI films, suggesting that the intermolecular packing of molecules at film interfaces differs from the bulk.

Publisher URL: http://dx.doi.org/10.1021/acs.jpcc.7b05514

DOI: 10.1021/acs.jpcc.7b05514

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.