Asuman Durmus

A neutral state green polymer with a superior transmissive light blue oxidized state.

This report highlights the synthesis of only the second green polymer in the literature, which possesses superior properties over the first: a highly transmissive light blue color in the oxidized state with high optical contrast and excellent switching properties.

Synthesis of N-substituted Pyrido[4,3-d]pyrimidines for the Large-Scale Production of Self-Assembled Rosettes and Nanotubes

N-substituted pyrido[4,3-d]pyrimidines are heterocycles which exhibit the asymmetric hydrogen bonding codes of both guanine and cytosine at 60° angles to each other, such that the molecules self-organize unambiguously into a cyclic hexamer, assembled via 18 intermolecular hydrogen bonds. The synthesis is straightforward and can be concluded in six steps from the commercially available malononitrile dimer. X-ray crystallographic analysis of the supermacrocyclic structure shows an undulating disk with a ca. 10.5 Å cavity, the centers of which do not overlap sufficiently to describe a channel in the solid state. However, AFM, SEM, and TEM imaging in solution reveals the formation of 1D nanostructures in agreement with their self-assembly into rosette supermacrocycles, which then stack linearly to form rosette nanotubes.

A green neutral state donor–acceptor copolymer for organic solar cells

We report on the photophysical and photovoltaic properties of a low band gap polymer bearing a quinoxaline moiety, poly(2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)quinoxaline) PDOPEQ, as an electron donor in bulk heterojunction solar cells blended with the acceptor 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene (PCBM). Devices were composed of PDOPEQ and varying amounts of PCBM (1:1, 1:2, 1:3, 1:4 w–w ratio). The components were spun cast from chlorobenzene (CB) and characterized by measuring current–voltage characteristics under simulated AM 1.5 conditions. The devices with 1:3 polymer to PCBM ratio exhibited short circuit current density (Jsc) of 0.8 mA cm−2, an open circuit voltage (Voc) of 0.2 V, and a fill factor (FF) of 0.3. Incident photon to current efficiency (IPCE) is also reported. The IPCE spectrum spans from 400 nm to 800 nm and exhibits a photocurrent contribution of ca. 5.5% at around 400 nm. The nanoscale morphology was investigated with atomic force microscopy (AFM). Photoinduced absorption spectroscopy confirms the photoinduced charge transfer in such donor acceptor blends.