Solid-state dye-sensitized solar cells using red and near-IR absorbing bodipy sensitizers

Boron-dipyrrin dyes, through rational design, yield promising new materials. With strong electron-donor functionalities and anchoring groups for attachment to nanocrystalline TiO2, these dyes proved useful as sensitizers in dye-sensitized solar cells. Their applicability in a solid-state electrolyte regime offers additional opportunities for practical applications. © 2010 American Chemical Society

Functional brush poly(2-ethyl-2-oxazine)s : synthesis by CROP and RAFT, thermoresponsiveness and grafting onto iron oxide nanoparticles

Brush polymers are highly functional polymeric materials combining the properties of different polymer classes and have found numerous applications, for example, in nanomedicine. Here, the synthesis of functional phosphonate‐ester‐bearing brush polymers based on poly(2‐oxazine)s is reported through a combination of cationic ring‐opening polymerization (CROP) of 2‐ethyl‐2‐oxazine and reversible addition‐fragmentation chain transfer (RAFT) polymerization. In this way, a small library of well‐defined (Đ ≤ 1.17) poly(oligo(2‐ethyl‐2‐oxazine) methacrylate) P(OEtOzMA)n brushes with tunable lower critical solution temperature (LCST) behavior and negligible cell toxicity is prepared. Upon deprotection, the phosphonic acid end‐group of the P(OEtOzMA)n brush enables the successful grafting‐onto iron oxide nanoparticles (IONPs). Colloidal stability of the particle suspension in combination with suitable magnetic resonance imaging (MRI) relaxivities demonstrates the potential of these particles for future applications as negative MRI contrast agents

Disorder in P3HT Nanoparticles Probed by Optical Spectroscopy on P3HT-b-PEG Micelles

We employ photoluminescence (PL) spectroscopy on individual nanoscale aggregates of the conjugated polymer poly(3-hexylthiophene), P3HT, at room temperature (RT) and at low temperature (LT) (1.5 K), to unravel different levels of structural and electronic disorder within P3HT nanoparticles. The aggregates are prepared by self-assembly of the block copolymer P3HT-block-poly(ethylene glycol) (P3HT-b-PEG) into micelles, with the P3HT aggregates constituting the micelles' core. Irrespective of temperature, we find from the intensity ratio between the 0-1 and 0-0 peaks in the PL spectra that the P3HT aggregates are of H-type nature, as expected from pi-stacked conjugated thiophene backbones. Moreover, the distributions of the PL peak ratios demonstrate a large variation of disorder between micelles (inter-aggregate disorder) and within individual aggregates (intra-aggregate disorder). Upon cooling from RT to LT, the PL spectra red-shift by 550 cm(-1), and the energy of the (effective) carbon-bond stretch mode is reduced by 100 cm(-1). These spectral changes indicate that the P3HT backbone in the P3HT-b-PEG copolymer does not fully planarize before aggregation at RT and that upon cooling, partial planarization occurs. This intra-chain torsional disorder is ultimately responsible for the intra-and inter-aggregate disorder. These findings are supported by temperature-dependent absorption spectra on thin P3HT films. The interplay between intra-chain, intra-aggregate, and inter-aggregate disorder is key for the bulk photophysical properties of nanoparticles based on conjugated polymers, for example, in hierarchical (super-) structures. Ultimately, these properties determine the usefulness of such structures in hybrid organic-inorganic materials, for example, in (bio-)sensing and optoelectronics applications

W-Band ENDOR of Light-Induced PPerAcr Anion Radicals in Double-Crystalline Donor-Bridge-Acceptor P3HT- b -PPerAcr Block Copolymer in Frozen Solution: Experimental and DFT Study

© 2018 American Chemical Society. Light-induced W-band electron nuclear double resonance and density functional theory of a spin density distribution study of poly-perylene bisimide acrylate (PPerAcr) anion radicals in double-crystalline donor-bridge-acceptor block copolymers (BCPs) are under consideration. Evidence of spin density sharing in the electron acceptor block, mainly distributed on the perylenediimide frame of PPerAcr without delocalization along the π-stack direction of the PPerAcr block in BCPs, was found at the low (50 K) temperature in frozen o-1,2-dichlorobenzene solution. The electron-hopping frequency between the anion and the nearby neutral PPerAcr of assembled π-stacks in P3HT-b-PPerAcr BCPs is limited by a frequency of around 108 Hz at temperatures below 50 K in the steady-state regime of continuous-wave light illumination

Roadmap on organic inorganic hybrid perovskite semiconductors and devices

Metal halide perovskites are the first solution processed semiconductors that can compete in their functionality with conventional semiconductors, such as silicon. Over the past several years, perovskite semiconductors have reported breakthroughs in various optoelectronic devices, such as solar cells, photodetectors, light emitting and memory devices, and so on. Until now, perovskite semiconductors face challenges regarding their stability, reproducibility, and toxicity. In this Roadmap, we combine the expertise of chemistry, physics, and device engineering from leading experts in the perovskite research community to focus on the fundamental material properties, the fabrication methods, characterization and photophysical properties, perovskite devices, and current challenges in this field. We develop a comprehensive overview of the current state of the art and offer readers an informed perspective of where this field is heading and what challenges we have to overcome to get to successful commercializatio