The PIs have previously found that a hierarchical morphology of donor and acceptor domains led to a high yield of electron transfer, enhanced exciton dissociation, and a high power conversion efficiency (PCE). In this proposal, they seek to combine theory and experiments in a coordinated approach to manipulate the nanostructured hierarchical morphologies in a controlled manner in order to quantify the influence of different morphological length scales on the optoelectronic properties and the efficiencies of solar cells composed of a semi-conducting donor and the fullerene acceptor system, PCBM. One way to ensure increased contact between the donor and acceptor phases is to use block copolymers (BCP), PTB7, as ?compatiblizers? to meld the two phases. Their approach is to find what the ?design rules? are for OPVs by undertaking a systematic combined experimental-theoretical investigation for designing efficient compatibilizers in the context of OPV applications. Their general plan is to synthesize PTB7 block copolymers, measure the ÷-interaction parameter between model polymer blocks, PTB7, and fullerene in thin film, multilayer blends, then elucidate and correlate the thermodynamics and microstructures of the BHJ blends to the morphology and optoelectronic properties of bulk heterojunction photovoltaics with PTB7 block copolymer compatibilizers.
