Hybrid heterojunctions of conjugated polymers and inorganic nanomaterials are a promising combination for obtaining high performance solar cells (SC). In this work we have explored new possible uses of the WS2 nanotubes (NTs) both as the only acceptor material blended with a polymer and in ternary systems mixed with a polymer and quantum dots (QDs). In particular we have spectroscopically investigated binary blends of poly(3-hexylthiophene) (P3HT) and WS2 NTs, P3HT and CdSe QDs, and ternary blends of P3HT, CdSe QDs and WS2 NTs. We report fluorescence quenching effects of the QD signal in the P3HT–CdSe–WS2 system with the increase of NT concentration. Static and time-resolved fluorescence studies reveal efficient resonant energy transfer from the QDs to the NTs upon photoexcitation. The evidence of energetic interaction between WS2 NTs and QDs opens new fields of application of WS2 NTs and holds very promising potential for improving charge transfer phenomena in the active layer of hybrid solar cells.
17 September 2018 in Proceedings of the National Academy of Sciences
Significance: The molecular basis of the mysterious ability of the clinically approved bioresorbable vascular scaffold to maintain radial strength after 9 mo of hydrolysis—despite a ∼40% reduction in the poly l -lactide molecular weight Mn —is an unexpected gradient in degradation revealed by X-ray microdiffraction. Hydrolysis is slowest in the 100- × 30-µm region where stress is concentrated during arterial contractions. This favorable gradient in hydrolysis arises from gradients in morphology created during crimping onto the angioplasty balloon: Small regions that undergo elongational deformation (<3% of scaffold) resist hydrolysis after deployment. This remarkably small amount of material (too low to detect in Mn measurements) has a disproportionate impact on strength because it forms precisely where the scaffold is most vulnerable to failure.