Azadipyrromethene-based Zn(II) complexes as nonplanar conjugated electron acceptors for organic photovoltaics.

The effectiveness of new a electron acceptor for organic solar cells is demonstrated. The acceptor is a homoleptic zinc(II) complex of 2,6-diphenylethynyl-1,3,7,9-tetraphenylazadipyrromethene. The high power-conversion efficiency obtained is attributed to the acceptor's 3D structure, which prevents crystallization and promotes a favourable nanoscale morphology, its high Voc , and its ability to contribute to light harvesting at 600-800 nm.

Tuning the dielectric properties of organic semiconductors via salt doping.

Enhancing the dielectric permittivity of organic semiconductors may open new opportunities to control charge generation and recombination dynamics in organic solar cells. The potential to tune the dielectric permittivity of organic semiconductors by doping them with redox inactive salts was explored using a combination of organic synthesis, electrical characterization, and time-resolved infrared spectroscopy. The addition of the salt, LiTFSI (lithium bis(trifluoro-methyl-sulfonyl)imide), to a conjugated polymer specifically designed to incorporate ions into its bulk phase increased the density of holes and enhanced the static dielectric permittivity of the polymer blend by more than an order of magnitude.

Conjugated block copolymer photovoltaics with near 3% efficiency through microphase separation.

Organic electronic materials have the potential to impact almost every aspect of modern life including how we access information, light our homes, and power personal electronics. Nevertheless, weak intermolecular interactions and disorder at junctions of different organic materials limit the performance and stability of organic interfaces and hence the applicability of organic semiconductors to electronic devices. Here, we demonstrate control of donor-acceptor heterojunctions through microphase-separated conjugated block copolymers.

Signatures of Multiphase Formation in the Active Layer of Organic Solar Cells from Resonant Soft X-ray Scattering.

Resonant soft X-ray scattering (RSOXS) is a complementary tool to existing reciprocal space methods, such as grazing-incidence small-angle X-ray scattering, for studying order formation in polymer thin films. In particular, RSOXS can exploit differences in absorption between multiple phases by tuning the X-ray energy to one or more resonance peaks of organic materials containing carbon, oxygen, nitrogen, or other atoms. Here, we have examined the structural evolution in poly(3-hexylthiophene-2,5-diyl)/[6,6]-phenyl-C-butyric acid methyl ester mixtures by tuning X-rays to resonant absorption energies of carbon and oxygen.