Tandem Solar Cells from Accessible Low Band-Gap Polymers Using an Efficient Interconnecting Layer.

Tandem solar cell architectures are designed to improve device photoresponse by enabling the capture of wider range of solar spectrum as compared to single-junction device. However, the practical realization of this concept in bulk-heterojunction polymer systems requires the judicious design of a transparent interconnecting layer compatible with both polymers. Moreover, the polymers selected should be readily synthesized at large scale (>1 kg) and high performance. In this work, we demonstrate a novel tandem polymer solar cell that combines low band gap poly isoindigo [P(T3-iI)-2], which is easily synthesized in kilogram quantities, with a novel Cr/MoO3 interconnecting layer. Cr/MoO3 is shown to be greater than 80% transparent above 375 nm and an efficient interconnecting layer for P(T3-iI)-2 and PCDTBT, leading to 6% power conversion efficiencies under AM 1.5G illumination. These results serve to extend the range of interconnecting layer materials for tandem cell fabrication by establishing, for the first time, that a thin, evaporated layer of Cr/MoO3 can work as an effective interconnecting layer in a tandem polymer solar cells made with scalable photoactive materials.

Polymeric catenanes synthesized via "click" chemistry and atom transfer radical coupling.

A novel route for the synthesis of polymeric catenanes was demonstrated by grafting an alkyne functionalized polymer onto a supramolecularly templated azide terminated ligand followed by ring closure via atom transfer radical coupling (ATRC). The polymeric catenane was characterized via GPC and AFM imaging.

A supramolecularly templated catenane initiator and a controlled ring expansion strategy.

We report the first synthesis of a catenated polymer via a ring-expansion strategy, which is based on a supramolecularly templated initiator. The high yielding synthesis and simple isolation method will enable the investigation and development of this unique polymer system for further applications.

Polymer catenanes via a supramolecularly templated ATRP initiator.

Synthesis of polymer catenanes via a living radical polymerization and supramolecular template approach are demonstrated. The ring closure was performed via atom transfer radical cross coupling (ATRC) to obtain polymer catenanes from the linear polymer metal complex precursor.