Organic small molecule solar cells are used as a test bed to investigate the influence of film morphology on the density of charge-transfer (CT) states. CT states are considered as precursors for charge generation and their energy as the upper limit for the open-circuit voltage in organic donor-acceptor solar cells. In this study the influence of morphology for two perylene donors [crystalline diindenoperylene (DIP) versus amorphous tetraphenyldibenzoperiflanthene (DBP)] with almost identical ionization energy is investigated. As acceptor material, the fullerene C 60 is used. By combining device measurements with optical and low-energy ultraviolet photoelectron spectroscopy, a comprehensive picture is obtained that describes how morphology and the connected density of states (DOS) affect device performance and the spectroscopic signature of CT states. Especially for the crystalline donor material DIP, strong exponential tail states reaching far into the gap are observed, which can be related to the presence of grain boundaries. A voltage-dependent filling of these states is identified as the origin of a blue shift of electroluminescence spectra with increasing applied voltage. Different approaches are compared to study the influence of static and dynamic disorder in the description of CT emission and absorption spectra of organic solar cells. Despite the fact that both donors yield almost identical CT energy (and, thus, the same open-circuit voltage) the Stokes shift between photocurrent and electroluminescence spectra and, concomitantly, the width of the CT DOS varies by more than a factor of 2. We discuss this observation in terms of the donoracceptor reorganization energy as well as an additional line broadening by static disorder. Remarkably, the more crystalline donor DIP shows a significant deviation from a Marcus-type description, while this is not the case for the amorphous DBP. This highlights the importance of film morphology in organic solar cells.

We demonstrated for the first time a facile and reproducible preparation of large-scale (∼40 m2) initiator layers for surface-initiated atom transfer radical polymerization (SI-ATRP) using a simple sol–gel solution of (p-chloromethyl)­phenyl­trimethoxysilane and tetraethoxysilane. Highly smooth and transparent initiator layers could be formed on various inorganic/organic substrates via a spin-, wire-bar-, or roll-to-roll-coating without any marked change in surface morphology or bulk properties at room temperature. Combining the advantages of this sol–gel approach and subsequent “paint on” SI-ATRP using a variety of waterborne monomers, we have succeeded in the formation of polymer brushes on large-scale real-life substrates (i.e., maximum 50 × 50 cm2) under ambient conditions (room temperature and open to the air) without any complicated apparatus or harsh reaction conditions.

We report a novel oil/water separation device, allowing continuous, high-speed, and highly efficient purification of large volumes of oily water. This device uses a pair of hydrophilic/hydrophobic polymer-brush-functionalized stainless steel meshes, which have antagonistic wetting properties, i.e., superoleophobic and superhydrophobic properties, when submerged in the opposite liquid phase. This device can purify large volumes of n-hexadecane/water mixture (∼1000 L) in a continuous process rather than in batches, to high purities (∼99.9% mol/mol) at high flow rates (∼5 mL s(-1) cm(-2)), unlike the oil/water separation meshes reported so far.

SummaryThe attachment ability of ladybird beetles Coccinella septempunctata was systematically investigated on eight types of surface, each with different chemical and topographical properties. The results of traction force tests clearly demonstrated that chemical surface properties, such as static/dynamic de-wettability of water and oil caused by specific chemical compositions, had no significant effect on the attachment of the beetles. Surface roughness was found to be the dominant factor, strongly affecting the attachment ability of the beetles.

This paper concerns a method of selecting a subset of features for a logistic regression model. Information criteria, such as the Akaike information criterion and Bayesian information criterion, are employed as a goodness-offit measure. The feature subset selection problem is formulated as a mixed integer linear optimization problem, which can be solved with standard mathematical optimization software, by using a piecewise linear approximation. Computational experiments show that, in terms of solution quality, the proposed method has superiority over common stepwise methods.

The free radial forearm flap is a very common material for penile reconstruction. Its major problems are donor-site morbidity with large depressive scar after skin grafting, urethral fistula due to insufficiency of suture line for the urethra, and need for microvascular anastomosis. A new method using combined bilateral island SCIP flaps for the urethra and penis is developed for gender identity disorder (GID) patients. The advantages of this method are minimal donor-site morbidity with a concealed donor scar, and possible one-stage reconstruction for a longer urethra of 22 cm in length without insufficiency, even for GID female-to-male patients. A disadvantage is poor sensory recovery.

Palm region extraction is one of the most important processes in palmprint recognition, since the accuracy of extracted palm regions has a significant impact on recognition performance. Especially in contactless recognition systems, a palm region has to be extracted from a palm image by taking into consideration a variety of hand poses. Most conventional methods of palm region extraction assume that all the fingers are spread and a palm faces to a camera. This assumption forces users to locate his/her hand with limited pose and position, resulting in impairing the flexibility of the contactless palmprint recognition system. Addressing the above problem, this paper proposes a novel palm region extraction method robust against hand pose. Through a set of experiments using our databases which contains palm images with different hand pose and the public database, we demonstrate that the proposed method exhibits efficient perfomance compared with conventional methods.

The complete electronic structure inside a practical organic photovoltaic (OPV) device consisting of a trilayer structure of copper‐phthalocyanine (CuPc), fullerene (C60), and bathocuproine (BCP) is demonstrated using low‐energy ultraviolet photoelectron spectroscopy (LE‐UPS) and photoelectron yield spectroscopy (PYS). The molecular orbital energy alignment and electrostatic potential distribution throughout the entire device is illustrated based on the LE‐UPS results. A favorable potential gradient to carry the photogenerated holes and electrons is manifested to be built spontaneously in the CuPc and BCP layers, respectively. Furthermore, the ultrahigh sensitivity measurements of LE‐UPS clearly unveil the distributions of faint density‐of‐states in the energy‐gap region in the organic films. Substantially barrierless contacts to both electrodes are fulfilled by the existence of these gap states. The electronic structure under simulated sunlight illumination is examined for the purpose of elucidating the electronic structures inside the working devices in the open‐circuit condition. These results indicate experimentally the electronic functionalities of each organic material, in particular of the BCP buffer layer, on the cell efficiency.