BackgroundExtant cubozoans are voracious predators characterized by their square shape, four evenly spaced outstretched tentacles and well-developed eyes. A few cubozoan fossils are known from the Middle Cambrian Marjum Formation of Utah and the well-known Carboniferous Mazon Creek Formation of Illinois. Undisputed cubozoan fossils were previously unknown from the early Cambrian; by that time probably all representatives of the living marine phyla, especially those of basal animals, should have evolved.MethodsMicroscopic fossils were recovered from a phosphatic limestone in the Lower Cambrian Kuanchuanpu Formation of South China using traditional acetic-acid maceration. Seven of the pre-hatched pentamerous cubozoan embryos, each of which bears five pairs of subumbrellar tentacle buds, were analyzed in detail through computed microtomography (Micro-CT) and scanning electron microscopy (SEM) without coating.ResultsThe figured microscopic fossils are unequivocal pre-hatching embryos based on their spherical fertilization envelope and the enclosed soft-tissue that has preserved key anatomical features arranged in perfect pentaradial symmetry, allowing detailed comparison with modern cnidarians, especially medusozoans. A combination of features, such as the claustrum, gonad-lamella, suspensorium and velarium suspended by the frenula, occur exclusively in the gastrovascular system of extant cubozoans, indicating a cubozoan affinity for these fossils. Additionally, the interior anatomy of these embryonic cubozoan fossils unprecedentedly exhibits the development of many new septum-derived lamellae and well-partitioned gastric pockets unknown in living cubozoans, implying that ancestral cubozoans had already evolved highly specialized structures displaying unexpected complexity at the dawn of the Cambrian. The well-developed endodermic lamellae and gastric pockets developed in the late embryonic stages of these cubozoan fossils are comparable with extant pelagic juvenile cubomedusae rather than sessile cubopolyps, whcih indicates a direct development in these fossil taxa, lacking characteristic stages of a typical cnidarian metagenesis such as planktonic planula and sessile polyps.

No abstract

The hole transporting layer (HTL) plays an important role in realizing efficient and stable perovskite solar cells (PSCs). In spite of intensive research efforts toward the development of HTL materials, low‐cost, dopant‐free hole transporting materials that lead to efficient and stable PSCs remain elusive. Herein, a simple polycyclic heteroaromatic hydrocarbon‐based small molecule, 2,5,9,12‐tetra(tert‐butyl)diacenaphtho[1,2‐b:1′,2′‐d]thiophenen, as an efficient HTL material in PSCs is presented. This molecule is easy to synthesize and inexpensive. It is hydrophobic and exhibits excellent film‐forming properties on perovskites. It has unusually high hole mobility and a desirable highest occupied molecular orbital energy level, making it an ideal HTL material. PSCs fabricated using both the n‐i‐p planar and mesoscopic architectures with this compound as the HTL show efficiencies as high as 15.59% and 18.17%, respectively, with minimal hysteresis and high long term stability under ambient conditions.

No abstract

Titanium dioxide (TiO 2 ) nanomaterials are widely considered to be state-of-the-art photocatalysts for environmental protection and energy conversion. However, the low photocatalytic efficiency caused by large bandgap and rapid recombination of photoexcited electrons and holes is a challenging issue that needs to be settled for their practical applications. Structure engineering has been demonstrated to be a highly promising approach to engineer the optical and electronic properties of the existing materials or even endow them with unexpected properties. Surface structure engineering has witnessed the breakthrough in increasing the photocatalytic efficiency of TiO 2 nanomaterials by creating a defect-rich or amorphous surface layer with black color and extension of optical absorption to the whole visible spectrum, along with markedly enhanced photocatalytic activities. In this review, the recent progress in the development of black TiO 2 nanomaterials is reviewed to gain a better understanding of the structure-property relationship with the consideration of preparation methods and to project new insights into the future development of black TiO 2 nanomaterials in photocatalytic applications.

No abstract

SCLC hole mobilities up to 8.72 Â 10 À2 cm 2 V À1 s À1 , amongst the highest reported hole mobility values for solution-processed smallmolecule organic semiconductors, are obtained from thermally annealed device-sized thin films of a thiophene-containing polycyclic aromatic hydrocarbon.Charge carrier (hole or electron) mobility is one important parameter affecting the performance of organic electronic/ optoelectronic devices including organic solar cells. 1 The highest hole mobilities (up to $45 cm 2 V À1 s À1 ) for organic semiconductors have been demonstrated on macroscopic, highly ordered, single crystals of conjugated molecules. 2,3 Benetting from the fast advancement of materials chemistry, the hole mobilities of organic-semiconductor thin lms, which are usually prepared by spin-coating or vacuum deposition, have also steadily increased to as high as 12 cm 2 V À1 s À1 . 4,5 Almost all of these high hole mobility values have been obtained by the eld effect transistor (FET) method. Compared to the FET method, which measures the mobility parallel to the electrodes under inuence of a gate bias, the space charge limited current (SCLC) method measures the mobility perpendicular to the electrodes. 6 The SCLC mobility is thus more relevant to solar cells. The FET and SCLC techniques are two of the most widely used methods to investigate charge carrier mobility in organic compounds. The SCLC mobility of organic-semiconductor thin lms is oen lower by a few orders of magnitude than their FET mobility. 6 Despite a few reports of high SCLC mobilities (up to 1.4 cm 2 V À1 s À1 ) measured in mesoscopic/microscopic areas of discotic liquid crystalline conjugated molecules, 3 the SCLC mobilities of macroscopic organic-semiconductor thin lms are generally much lower, ranging from 10 À6 to 10 À4 cm 2 V À1 s À1 . 6-8Among myriads of conjugated molecules, polycyclic aromatic hydrocarbons (PAHs) have drawn the most interest and have been widely investigated for electronic applications. 9-16 Their oen planar or near-planar geometry and extended p-delocalization can induce strong p-p stacking resulting in potentially high charge carrier mobility along the stacked PAH column. 11,15,16 Indeed, the majority of the reported highest SCLC hole mobilities are obtained from PAHs. 2,3 A thiophene-containing fused PAH, namely 2,5,9,12-tetra(tertbutyl)diacenaphtho[1,2-b:1 0 ,2 0 -d]thiophene (DAT) (1) (Fig. 1a), was rst synthesized approximately een years ago but has not drawn much attention. 17,18 Nor have its electronic properties/ Fig. 1 (a and b) Structures of compounds 1 and 2. Energy-minimized geometries of 1 (c and e) and 2 (d and f) from different views obtained using DFT calculations at the B3LYP/6-31G(d) level. † Electronic supplementary information (ESI) available: Experimental details; synthesis and characterization of 1 and 2; visualized LUMO+1, LUMO, HOMO and HOMOÀ1 orbitals of the energy-minimized conformers; UV-vis absorption and orescence emission spectra; cyclic voltammograms; DSC thermograms. See

Donor‐acceptor conjugated polymers containing a new imide‐functionalized naphthodithiophene (INDT) as the acceptor unit and a 2,2'‐bithiophene with varied substituents as the donor unit have been synthesized. The bandgaps of these polymers depend strongly on the dihedral angle of the 2,2'‐bithiophene unit. The 3,3'‐dialkoxy substitution (polymers PDOR/PBOR) leads to near planar bithiophene conformation due to the well‐known S–O short contact, while the 3,3'‐dialkyl substitution (polymer PDR) results in significant twisting due to the steric effect. Consequently PDOR/PBOR shows the lowest bandgap of 1.82/1.85 eV while PDR has a bandgap of 2.38 eV. Bulk‐heterojunction solar cells of the polymer/fullerene blends have been fabricated. Preliminary results show that PBOR gives the best device performance with power conversion efficiencies as high as 2.45% in air without any thermal annealing treatment, indicating the promising potential of INDT‐containing conjugated polymers for efficient solar cells. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3818–3828