The objective of this program is to develop room-temperature electrophosphorescence (RT-EP) utilizing purely organic materials. These materials termed ?molecular alloys? are efficient phosphors as they transport charge, induce intersystem crossing from the singlet to triplet excited state, and lock the phosphors in a matrix preventing their nonradiative relaxation. The materials displaying RT-EP will be investigated using optical spectroscopy and force microscopy (AFM, STM, C-AFM, KPM). Studies of polaron/exciton dynamics in films via photoluminescence (PL)- and photoinduced absorption (PA)-detected magnetic resonance (PLDMR and PADMR, respectively) will be carried out together with studies of polaron and exciton dynamics in the OLEDs using electroluminescence (EL)- and electrical current-detected magnetic resonance (ELDMR and EDMR, respectively). Intellectual merit: The intellectual merit: Electrophosphorescence from purely organic materials has so far been observed only at low temperature (~15 K), which prevents practical applications. The PVD materials termed ?molecular alloys? allow for efficient (EQE~3%) RT-EP in experimental devices. Thus, studies aimed at detailed understanding of the processes taking place in the all-organic phosphors-based devices are important. Broader impact: The broader impacts are: Basic science proposed: An understanding of new all-organic materials that facilitate ISC while limiting nonradiative relaxation of the triplets and investigating physics of corresponding OLEDs will be achieved. Energy-conservation relevance: OLEDs as efficient light sources that would not require precious/heavy metals would be more environmentally friendly. Interdisciplinary Education: Collaboration between the two research groups with expertise in PVD, materials chemistry, condensed-matter physics, device fabrication and characterization will enrich education, encourage interdisciplinary thinking, and facilitate student exchange.
