In hybrid solar cells (HSCs) the inorganic/organic interface plays a crucial role for the power conversion efficiency (PCE) via the phase compatibility, energy level alignment and the interfacial dipole orientation. Here, we present a method for the synthesis of defined polymeric interfacial modifiers. Functionalized Pd(II) initiators were isolated and used, with AB-type bromo-thiophene-boronic acid ester monomers, in a controlled Suzuki-Miyaura Coupling polymerization (SMCP). By varying the initiator to monomer ratio regioregular oligo- to polythiophenes with chain lengths from 5 to 50 repeat units with a narrow molecular weight distribution and defined functionalized end groups are obtained. The ability of diethyl phosphonates to bind strongly via condensation with titania surfaces was exploited for the utilization as interfacial modifiers in titania/P3HT HSCs. The influence of the chain length and the electron deficient aryl-phosphonate end groups on the PCE is rationalized.

Phosphonate functionalized poly-3-hexylthiophenes by controlled Suzuki-Miyaura coupling polymerization for interface modification in hybrid solar cells

253rd National Meeting (2017)

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