| AVS 54th International Symposium | |
| Surface Science | Wednesday Sessions |
| Session SS2+EM+TF-WeM |
| Session: | SAMs and Organic Films I |
| Presenter: | J.E. Reutt-Robey, University of Maryland |
| Authors: | J.E. Reutt-Robey, University of Maryland B. Xu, Yanshan University, China C.G. Tao, University of Maryland D.B. Dougherty, National Institute of Standards and Technology W. Jin, University of Maryland |
| Correspondent: | Click to Email |
Multi-component aromatic molecular films are of increasing interest in photovoltaic technologies and other organic electronic applications. Binary organic films offer the potential to tailor film structure on the nanoscale to optimize device performance through phase selection, domain size, distribution and orientation. A basic understanding of the factors that control structure in binary molecular films is thus important to advance these materials technologies. We report STM-studies of structure evolution in model donor-acceptor systems, such as ACA:C60 and Pentacene:C60. Films prepared by sequential physical vapor deposition onto Ag(111) substrates under UHV are monitored directly with an integrated UHV-STM. We demonstrate how ACA:C60 film growth conditions can be adjusted to selectively fabricate films that range from phase-separated hexagonal -C60 and chain-phase [4 0, 2 ]-ACA domains to intermixed co-crystalline chiral domains comprised of C60-terminated ACA pinwheels. Films produced with arbitrary composition generally lead to complex multi-phase structures. Predeposited ACA films with single phase structures provide the most effective pathway to single phases of intermixed structures. For example, the intermixed chiral phase is only accessible from the 2-D ACA molecular gas, whereas extended C60 chain structures may be accessed only from the dimer-phase [12 2, 6 5]-ACA domains. We apply lessons from the ACA:C60 system to Pentacene:C60, mixtures, utilizing the 2-D pentacene gas to access an intermixed honeycomb Pentacene:C60 phase.