Hussein Awada

Surface-initiated polymerization of A–A/B–B type conjugated monomers by palladium-catalyzed Stille polycondensation: towards low band gap polymer brushes

A surface-initiated polycondensation which enables access to well-defined core–shell nanoparticles is described. Stille polymerization was initiated from the surface of palladium catalyst-immobilized zinc oxide nanorods. For the first time, a low band gap polymer, poly[(4,4′-bis(2-ethylhexyl)dithieno-[3,2-b:2′,3′-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (PSBTBT), was anchored on zinc oxide nanorods to create hybrid materials with tunable photophysical properties.

Bis-Azide Low-Band Gap Cross-Linkable Molecule N3-[CPDT(FBTTh2)2] to Fully Thermally Stabilize Organic Solar Cells Based on P3HT:PC61BM

We synthesized a novel bis-azide low-band gap cross-linkable molecule N3-[CPDT(FBTTh2)2] with wide absorption. This compound is of interest as an additive in polymer/fullerene bulk heterojunction solar cells. In addition to providing efficient thermal stabilization of the morphology, the additive can harvest additional solar light compared with pristine poly(3-hexyl thiophene) to improve the power-conversion efficiency (PCE). The additional donor material was visualized from the appearance of additional external quantum efficiency contributions between 650 and 800 nm. An open-circuit voltage increase of ∼2% compensates the decrease in the short-circuit current of ∼2% to achieve a fully thermally stabilized PCE of 3.5% after 24 h of annealing at 150 °C.

Synthesis and photovoltaic properties of a new donor-acceptor conjugated polymer based on fluorinated benzothiadiazole units

A novel fluorinated copolymer (PDTSffBT) based on dithienosilole donor unit and fluorinated benzothiadiazole acceptor unit has been synthesized for polymer solar cells. This copolymer exhibits a deeper HOMO energy level compared to that of hydrogenated benzothiadiazole-based copolymer (PDTSBT), resulting in high open-circuit voltages well exceeding 0.75 V. The introduction of the two electron-withdrawing fluorine atoms on the benzothiadiazole unit also leads to an increase in the molar extinction coefficient as well as the interchain interaction in the PDTSffBT copolymer with respect to its analogue PDTSBT copolymer. Power conversion efficiency (PCE) of the device using PDTSffBT:PC71BM as active layer (2.93 %) is much higher than of a PDTSBT:PC71BM (1.64 %) counterpart under identical conditions.