Charge-carrier relaxation dynamics of poly(3-hexylthiophene)-coated gold hybrid nanoparticles

Recent Advances of Plasmonic Organic Solar Cells: Photophysical Investigations

The surface plasmon resonance (SPR) of metallic nanomaterials, such as gold (Au) and silver (Ag), has been extensively exploited to improve the optical absorption, the charge carrier transport, and the ultimate device performances in organic photovoltaic cells (OPV). With the incorporation of diverse metallic nanostructures in active layers, buffer layers, electrodes, or between adjacent layers of OPVs, multiple plasmonic mechanisms may occur and need to be distinguished to better understand plasmonic enhancement. Steady-state photophysics is a powerful tool for unraveling the plasmonic nature and revealing plasmonic mechanisms such as the localized surface plasmon resonance (LSPR), the propagating plasmon-polariton (SPP), and the plasmon-gap mode. Furthermore, the charge transfer dynamics in the organic semiconductor materials can be elucidated from the transient photophysical investigations. In this review article, the basics of the plasmonic mechanisms and the related metallic nanostructures are briefly introduced. We then outline the recent advances of the plasmonic applications in OPVs emphasizing the linkage between the photophysical properties, the nanometallic geometries, and the photovoltaic performance of the OPV devices.

Direct Observation of an Efficient Triplet Exciton Diffusion Process in a Platinum-Containing Conjugated Polymer

We report the synthesis and characterization of a conjugated polymer incorporated with cyclometalated platinum complexes on the main chain. The polymer may serve as an efficient triplet sensitizer in light-harvesting systems. The photophysical properties of the polymer were studied by nanosecond and femtosecond time-resolved transient absorption spectroscopies. After excitation, an energy-transfer process from the thiophene units on the conjugated main chain to the singlet excited state of the Pt complex moieties occurred in less than 150 fs. The subsequent intersystem crossing process resulted in the formation of a triplet excited state at the Pt complex moieties in ∼3.2 ps, which was then followed by an efficient triplet diffusion process that led to the formation of triplet excitons on the polymer main chain in ∼283 ps. This proposed efficient triplet sensitized polymer system not only enhances the exciton diffusion length but also reduces energy loss in the process, which displays remarkable implications in the design of novel materials for triplet sensitized solar cells.

A colloidal system of polythiophene-grafted edge-gold-coated silver nanoprisms with enhanced optical properties and stability

P3HT has been grafted to edge-gold-coated silver nanoprisms to have feasible-process ability, enhanced optical properties, and high stability.

Highly luminescent gold nanoparticles: effect of ruthenium distance for nanoprobes with enhanced lifetimes

The photophysical properties of gold nanoparticles, AuNPs, with sizes of 13, 50 and 100 nm in diameter, coated with surface-active ruthenium complexes have been studied to investigate the effect of the distance of the ruthenium luminescent centre from the gold surface. Luminescence lifetimes of the three ruthenium probes, RuS1, RuS6 and RuS12, with different length spacer units between the surface active groups and the ruthenium centre were taken. The metal complexes were attached to AuNP13, AuNP50 and AuNP100 via thiol groups using a method of precoating the nanoparticles with a fluorinated surfactant. The luminescence lifetime of the longer spacer unit complex, RuS12, was enhanced by 70% upon attachment to the AuNP when compared to the increase of the short and medium linker unit complexes, RuS1 (20%) and (RuS6 40%) respectively. The effect of the surfactant in the lifetime increase of the ruthenium coated AuNPs was shown to be larger for the medium spacer probe, RuS6. There was no effect of the change of the size of the AuNPs from 13 to 50 or 100 nm.

Formation and decay of charge carriers in aggregate nanofibers consisting of poly(3-hexylthiophene)-coated gold nanoparticles

Hybrid nanofibers consisting of poly(3-hexylthiophene)-coated gold nanoparticles have been facilely fabricated and comprehensively investigated by time-resolved emission and transient-absorption spectroscopy.

Controlled synthesis of multi-armed P3HT star polymers with gold nanoparticle core

Well-defined multi-armed P3HT star polymers with a gold nanoparticle (NP) core were synthesized by an arm-first method based on a ligand exchange reaction between linear end-functionalized P3HT (P3HT-SH) and gold NPs.