Publishes on Organic Electronics and Photovoltaics, Conducting polymers and applications, Organic Light-Emitting Diodes Research. 1.1k papers and 161.8k citations.
The carrier collection efficiency (η c ) and energy conversion efficiency (η e ) of polymer photovoltaic cells were improved by blending of the semiconducting polymer with C 60 or its functionalized derivatives. Composite films of poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) and fullerenes exhibit η c of about 29 percent of electrons per photon and η e of about 2.9 percent, efficiencies that are better by more than two orders of magnitude than those that have been achieved with devices made with pure MEH-PPV. The efficient charge separation results from photoinduced electron transfer from the MEH-PPV (as donor) to C 60 (as acceptor); the high collection efficiency results from a bicontinuous network of internal donor-acceptor heterojunctions.
We present a theoretical study of soliton formation in long-chain polyenes, including the energy of formation, length, mass, and activation energy for motion. The results provide an explanation of the mobile neutral defect observed in undoped ${(\mathrm{CH})}_{x}$. Since the soliton formation energy is less than that needed to create band excitation, solitons play a fundamental role in the charge-transfer doping mechanism.
Self-localized nonlinear excitations (solitons, polarons, and bipolarons) are fundamental and inherent features of quasi-one-dimensional conducting polymers. Their signatures are evident in many aspects of the physical and chemical properties of this growing class of novel materials. As a result, these polymers represent an opportunity for exploring the novel phenomena associated with topological solitons and their linear confinement which results from weakly lifting the ground-state degeneracy. The authors review the theoretical models that have been developed to describe the physics of polyacetylene and related conducting polymers and summarize the relevant experimental results obtained for these materials. An attempt is made to assess the validity of the soliton model of polyacetylene and its generalization to related systems in which the ground-state degeneracy has been lifted.
When silvery films of the semiconducting polymer, trans‘polyacetylene’, (CH)x, are exposed to chlorine, bromine, or iodine vapour, uptake of halogen occurs, and the conductivity increases markedly (over seven orders of magnitude in the case of iodine) to give, depending on the extent of halogenation, silvery or silvery-black films, some of which have a remarkably high conductivity at room temperature.