Elena E. Sheina

Tuning the Electrical Conductivity and Self-Assembly of Regioregular Polythiophene by Block Copolymerization: Nanowire Morphologies in New Di- and Triblock Copolymers

could self-as-sembleintoanumberofnanoscalemorphologies, such as lamellar, spherical, cylindrical, andvesicularstructures,whichwouldleadtothepossibilitythatnew electronic/structural copolymers could be designed,synthesized, and assembled as components in new nano-devices. Here we present a veryeasysynthetic method toproducealargenumberofwell-definedblockcopolymersandpolyurethane elastomers containing regioregular polythio-phenes. Despite having low percentages of regioregularpolythiophenes, these new copolymers have very high con-ductivities(oftheorderofafewScm

Structural variation of donor–acceptor copolymers containing benzodithiophene with bithienyl substituents to achieve high open circuit voltage in bulk heterojunction solar cells

Three new donor–acceptor copolymers P1, P2, and P3 were synthesized with benzodithiophene with bithienyl substituents as the donor and 5,6-difluorobenzo[c][1,2,5]thiadiazole, 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole, and 5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole as the acceptors, respectively. The insertion of thiophene spacer between the donor and the acceptor broadened the absorption of the polymers P2 and P3 and resulted in a red shift of ∼30 nm as compared to that of the polymer P1. However, the inclusion of fluorine atoms on the polymer had detrimental effects on the photovoltaic properties of the polymers. The synthesized donor–acceptor polymers were tested in bulk heterojunction (BHJ) solar cells with [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) acceptor. Polymer P2 gave a PCE of 3.52% with PC71BM in which the active layer was prepared in chloroform with 3% v/v 1,8-diiodooctane (DIO) additive. The effect of fluorine substitution and thiophene group insertion on the UV/Vis absorbance, photovoltaic performances, morphology, and charge carrier mobilities for the polymers are discussed.

Advances in Plexcore active layer technology systems for organic photovoltaics: roof-top and accelerated lifetime analysis of high performance organic photovoltaic cells

We report NREL-certified efficiencies and initial lifetime data for organic photovoltaic (OPV) cells based on Plexcore PV photoactive layer and Plexcore HTL-OPV hole transport layer technology. Plexcore PV-F3, a photoactive layer OPV ink, was certified in a single-layer OPV cell at the National Renewable Energy Laboratory (NREL) at 5.4%, which represents the highest official mark for a single-layer organic solar cell. We have fabricated and measured P3HT:PCBM solar cells with a peak efficiency of 4.4% and typical efficiencies of 3 - 4% (internal, NREL-calibrated measurement) with P3HT manufactured at Plextronics by the Grignard Metathesis (GRIM) method. Outdoor and accelerated lifetime testing of these devices is reported. Both Plexcore PV-F3 and P3HT:PCBM-based OPV cells exhibit >750 hours of outdoor roof-top, non-accelerated lifetime with less than 8% loss in initial efficiency for both active layer systems when exposed continuously to the climate of Western Pennsylvania. These devices are continuously being tested to date. Accelerated testing using a high-intensity (1000W) metal-halide lamp affords shorter lifetimes; however, the true acceleration factor is still to be determined.

Benzodithiophene homopolymers synthesized by Grignard metathesis (GRIM) and Stille coupling polymerizations

Poly{4,8-bis(95-dodecylthiophene-2-yl)benzo[1,2-b:4,5-b′]dithiophene} has been synthesized by both Grignard metathesis (P1) and Stille coupling polymerizations (P2). Polymers P1 and P2 were characterized and their optoelectronic properties, charge carrier mobilities, and photovoltaic properties were compared. The field-effect mobilities of the polymers were measured on both untreated and heptadecafluoro-1,1,2,2-tetrahydro-decyl-1-trimethoxysilane (FS) treated organic field effect transistor (OFET) devices. The polymers were also evaluated in bulk heterojunction (BHJ) solar cells with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor.