Colloidal Ag nanoparticles coated with L‐glutathione attached to bimane chromophores were studied by absorption, circular dichroism (CD), and fluorescence spectroscopies. The absorption and CD spectra were resonantly enhanced by Ag surface plasmons. The wavelength and particle‐size dependence of the enhancement indicated that an electromagnetic “antenna” effect is in action.

The photosystem I (PS I) protein is one of nature's most efficient light harvesting complexes and exhibits outstanding optoelectronic properties. Here we demonstrate how metal nanoparticles which act as artificial antennas can enhance the light absorption of the protein. This hybrid system shows an increase in light absorption and of circular dichroism over the entire absorption band of the protein rather than at the specific plasmon resonance wavelength of spherical metal nanoparticles (NPs). This is explained by broad-resonant and nonresonant field enhancements caused by metal NP aggregates, by the high dielectric constant of the metal, and by NP-PS I-NP antenna junctions which effectively enhance light absorption in the PS I.

Seeded semiconductor nanorods represent a unique family of quantum confined materials that manifest characteristics of mixed dimensionality. They show polarized emission with high quantum yield and fluorescence switching under an electric field, features that are desirable for use in display technologies and other optical applications. So far, their robust synthesis has been limited mainly to CdSe/CdS heterostructures, thereby constraining the spectral tunability to the red region of the visible spectrum. Herein we present a novel synthesis of CdSe/CdZnS seeded nanorods with a radially graded composition that show bright and highly polarized green emission with minimal intermittency, as confirmed by ensemble and single nanorods optical measurements. Atomistic pseudopotential simulations elucidate the importance of the Zn atoms within the nanorod structure, in particular the effect of the graded composition. Thus, the controlled addition of Zn influences and improves the nanorods' optoelectronic performance by providing an additional handle to manipulate the degree confinement beyond the common size control approach. These nanorods may be utilized in applications that require the generation of a full, rich spectrum such as energy-efficient displays and lighting.

Thin-film organic near-infrared (NIR) photodiodes can be essential building blocks in the rapidly emerging fields including the internet of things and wearable electronics. However, the demonstration of NIR organic photodiodes with not only high responsivity but also low dark current density that is comparable to that of inorganic photodiodes, for example, below 1 nA cm–2 for silicon photodiodes, remains a challenge. In this work, we have demonstrated non-fullerene acceptor-based NIR photodiodes with an ultralow dark current density of 0.2 nA cm–2 at −2 V by innovating on charge transport layers to mitigate the reverse charge injection and interfacial defect-induced current generation. The same device also shows a high external quantum efficiency approaching 70% at 850 nm and a specific detectivity of over 1013 Jones at wavelengths up to 940 nm. Furthermore, the versatility of our approach for mitigating dark current is demonstrated using a NIR photodetector utilizing different non-fullerene systems. Finally, the practical application of NIR organic photodiodes is demonstrated with an image sensor integrated on a silicon CMOS readout. This work provides new insight into the device stack design of low-dark current NIR organic photodiodes for weak light detection.

Phone: þ972 2 6584515, Fax: þ972 2 6584148Large-scale lateral alignment of nanorods (NRs) is of interest for manifestation of their anistropic properties including polarized emission and directional electrical transport. This study investigates the utility of mechanical rubbing for macroscopic scale alignment of colloidal semiconductor NRs. CdSe/CdS seeded-rods, exhibiting linearly polarized emission, are aligned by mechanical rubbing of a spin-coated glass substrate. The dragging force exerted by the rubbing fibers results in deflection and reorientation of the NRs along the rubbing direction. The rubbed samples were characterized by various methods including absorption, polarized emission, optical fluorescence microscopy, atomic force microscopy, and ultra-high resolution scanning electron microscopy. The emission polarization contrast ratio (CR), defined as the ratio between emission intensities parallel and perpendicular to the rubbing direction, was used to characterize the rods alignment.The effects of substrate treatments on the CR were studied, showing that partially hydrophobic surface provides optimal conditions for alignment. Excess organic ligands added to the deposited NR solution strongly affect the extent of alignment. This was studied for a series of NR samples of different dimensions and an optimal additive ratio of $3 ligand molecules per 1 nm 2 NR surface area was found to yield the highest CR. Average CR values of 3.5 were detected over the entire 6 cm 2 substrate area, with local values exceeding 4.5. While samples of rubbed spherical quantum dots and spincoated films of NRs show no emission polarization, the emission intensity from rubbed NR samples is polarized obeying Malus' law (wherein, the intensity is proportional to cos 2 (u)). Mechanical rubbing, well known for its use in LC devices, may be considered as a method for large-scale alignment of NRs on substrates.1 Introduction Semiconductor nanocrystals (NCs) manifest unique, size-dependent, electronic, and optical properties [1,2]. Advancements in the synthesis of these colloidal NCs yielded high quantum efficiencies [3] and control of the attained morphology [4,5]. Of particular interest are elongated semiconductor NCs, known as nanorods (NRs), exhibiting anisotropic properties such as polarized emission and lasing [6][7][8][9][10][11][12]. Alignment of NRs on large scales by facile means is therefore of fundamental interest for the study of their anisotropic collective behavior and is also relevant for different optoelectronic applications of NRs. In this work, we examined the use of mechanical rubbing to induce NR alignment on large macroscopic scale areas. Effects of rubbing parameters, the substrate surface functionalization and excess organic ligands on the rubbing process, and the resulting alignment were investigated.