Building a qualitative and quantitative understanding of optoelectronic processes in materials for solar energy conversion: From molecules to material

PHYS 216

Andre J. Gesquiere, andre@mail.ucf.edu, Daeri Tenery, daeritenery@yahoo.com, and Zhongjian Hu, zjhu05@gmail.com. NanoScience Technology Center and Department of Chemistry, University of Central Florida, 12424 Research Parkway Suite 400, Orlando, FL 32826
Composite conjugated polymer (MEH-PPV, P3HT)-fullerene (PCBM) nanoparticles, representing a new class of nanoparticles, were fabricated and their optoelectronic properties were investigated. Characterization of the nanoparticles with solution- and single particle spectroscopy reveals the extent to which variations in polymer chain folding and interactions between polymer chains and fullerenes affect material morphology, spectral- and optoelectronic properties, providing a detailed molecular scale insight in the morphological effects at play in the active layers of bulk heterojunction organic photovoltaic devices. Experiments where acquisition of fluorescence emission rate was time-synchronized with a modulating electrical field applied to a device sample allowed us to identify the involved molecular states in interfacial charge separation. In addition, we determined the rate of charge separation under different electric field strengths, proving that the energetics and dynamics of the light-induced charge separation in organic photovoltaic devices is affected by the internal electrical fields present during device operation.