Testing Real Quantum Theory in an Optical Quantum Network.

Quantum theory is commonly formulated in complex Hilbert spaces. However, the question of whether complex numbers need to be given a fundamental role in the theory has been debated since its pioneering days. Recently it has been shown that tests in the spirit of a Bell inequality can reveal quantum predictions in entanglement swapping scenarios that cannot be modeled by the natural real-number analog of standard quantum theory.

Quantum theory based on real numbers can be experimentally falsified.

Although complex numbers are essential in mathematics, they are not needed to describe physical experiments, as those are expressed in terms of probabilities, hence real numbers. Physics, however, aims to explain, rather than describe, experiments through theories. Although most theories of physics are based on real numbers, quantum theory was the first to be formulated in terms of operators acting on complex Hilbert spaces.

Tuning fullerene miscibility with porphyrin-terminated P3HTs in bulk heterojunction blends.

Understanding and manipulating the miscibility of donor and acceptor components in the active layer morphology is important to optimize the longevity of organic photovoltaic devices and control power conversion efficiency. In pursuit of this goal, a "porphyrin-capped" poly(3-hexylthiophene) was synthesized to take advantage of strong porphyrin:fullerene intermolecular interactions that modify fullerene miscibility in the active layer. End-functionalized poly(3-hexylthiophene) was synthesized via catalyst transfer polymerization and subsequently functionalized with a porphyrin moiety via post-polymerization modification.

Resonant Soft X-Ray Scattering Provides Protein Structure with Chemical Specificity.

We introduce resonant soft X-ray scattering (RSoXS) as an approach to study the structure of proteins and other biological molecules in solution. Scattering contrast calculations suggest that RSoXS has comparable or even higher sensitivity than hard X-ray scattering because of contrast generated at the absorption edges of constituent elements, such as carbon and oxygen. Here, we demonstrate that working near the carbon edge reveals the envelope function of bovine serum albumin, using scattering volumes of 10 μL that are multiple orders of magnitude lower than traditional scattering experiments.

Impact of Low Molecular Weight Poly(3-hexylthiophene)s as Additives in Organic Photovoltaic Devices.

Despite tremendous progress in using additives to enhance the power conversion efficiency of organic photovoltaic devices, significant challenges remain in controlling the microstructure of the active layer, such as at internal donor-acceptor interfaces. Here, we demonstrate that the addition of low molecular weight poly(3-hexylthiophene)s (low-MW P3HT) to the P3HT/fullerene active layer increases device performance up to 36% over an unmodified control device. Low MW P3HT chains ranging in size from 1.

Elemental mapping of interfacial layers at the cathode of organic solar cells.

One of the limitations in understanding the performance of organic solar cells has been the unclear picture of morphology and interfacial layers developed at the active layer/cathode interface. Here, by utilizing the shadow-Focused Ion Beam technique to enable energy-filtered transmission electron microscopy imaging in conjunction with X-ray photoelectron spectroscopy (XPS) experiments, we examine the cross-section of polythiophene/fullerene solar cells to characterize interfacial layers near the semiconductor-cathode interface. Elemental mapping reveals that localization of fullerene to the anode interface leads to low fill factors and S-shaped current-voltage characteristics.

Chemical bath deposition of ZnO nanowires at near-neutral pH conditions without hexamethylenetetramine (HMTA): understanding the role of HMTA in ZnO nanowire growth.

Chemical bath deposition (CBD) is an inexpensive and reproducible method for depositing ZnO nanowire arrays over large areas. The aqueous Zn(NO(3))(2)-hexamethylenetetramine (HMTA) chemistry is one of the most common CBD chemistries for ZnO nanowire synthesis, but some details of the reaction mechanism are still not well-understood. Here, we report the use of in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy to study HMTA adsorption from aqueous solutions onto ZnO nanoparticle films and show that HMTA does not adsorb on ZnO.