Organic photovoltaic devices based on p-conjugated small molecules represent an attractive approach for low-cost solar energy conversion, in part due to their tunable optoelectronic properties and amenability to vacuum deposition. However, the power conversion efficiencies of these devices can be limited by poor nanoscale morphology of the bulk-heterojunction (BHJ) active layer. Top-down attempts to improve BHJ devices, such as annealing, have so far achieved only limited success. Herein we employ a �bottom-up� approach, in which p-conjugated donor chromophores are retrofitted with an H-bonding unit such that programmed self-assembly is encouraged. The H-bonding motif selected, known to aggregate into trimeric assemblies under appropriate conditions, was coupled to a branched quaterthiophene chromophore. Structural analogues lacking H-bonding capability were likewise prepared. Using these non-H-bonding analogues as a control, preliminary results show favorable aggregation of the compounds in solution and in bulk, and three-fold improved performance in devices.

Self-assembling p-conjugated donor materials for improved BHJ device performance

246th National Meeting (2013)

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