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A class of D−π–A–A type small-molecule donor materials used in heterojunction solar cell has been designed and investigated by means of quantum chemical calculations. A linear D−π–A molecule containing triphenylamine (TPA), ethynylbenzene (EB), and diketopyrrolopyrrole (DPP) is end-capped with various electron acceptors to further enhance its electron-accepting capability. To gain a better understanding of the effects of terminal acceptors on the modulation of electronic and optical properties of D−π–A molecule, the geometrical structures, light-absorbing capacities, frontier orbitals, exciton binding energies, intramolecular charge transfer (ICT) properties, and exciton dissociation rates at the interface are analyzed in detail to establish the structure–property relationships for D−π–A–A type materials. The calculated results indicate that the terminal modulation is an effective strategy to enhance light-absorbing capacities, ICT properties, and exciton dissociation at the heterojunction interface. The predicted power conversion efficiency (PCE) of designed molecules by Scharber diagram could reach up to more than 8%, which sheds light on the exploration of high-performance small-molecule donors for photovoltaic applications.

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The construction of highly active, durable, and cost‐effective catalysts is urgently needed for green hydrogen production. Herein, catalysts consisting of high‐density Pt (24 atoms nm−2) and Ir (32 atoms nm−2) single atoms anchored on Co(OH)2 were constructed by a facile one‐step approach. Remarkably, Pt1/Co(OH)2 and Ir1/Co(OH)2 only required 4 and 178 mV at 10 mA cm−2 for hydrogen evolution reaction and oxygen evolution reaction, respectively. Moreover, the assembled Pt1/Co(OH)2//Ir1/Co(OH)2 system showed mass activity of 4.9 A mgnoble metal−1 at 2.0 V in an alkaline water electrolyzer, which is 316.1 times higher than that of Pt/C//IrO2. Mechanistic studies revealed that reconstructed Ir−O6 single atoms and remodeled Pt triple‐atom sites enhanced the occupancy of Ir−O bonding orbitals and improved the occupation of Pt−H antibonding orbital, respectively, contributing to the formation of the O−O bond and the desorption of hydrogen. This one‐step approach was also generalized to fabricate other 20 single‐atom catalysts.

The electronic structures and charge transport properties of a series of dimers of dithienothiophenes are investigated by means of quantum chemical calculations. To gain a better understanding of the effects of the structural symmetry and linking mode on dimers, the geometrical structures, molecular reorganization energies upon getting or losing electrons, molecular ionization potentials (IPs) and electron affinities (EAs), molecular aromaticities, frontier molecular orbitals, as well as charge mobilities are analyzed in detail to determine the structure-property relationships for the investigated dimers of dithienothiophenes. The calculated results show that the vinylene-linked dimers have the advantages over the directly single-bond linked dimers because of the large extent of π conjugation and thus enhanced π − π stacking interactions in their crystal structures. The molecular symmetry could affect the electron density distributions in the molecules, and further determine the molecular orientations and intermolecular arrangements. The high molecular symmetry could facilitate the molecular packing in order, thus enhancing the charge transport. The theoretical characterization of these dimers in combination with experimental results indicate that high symmetrical vinylene-bridged dimers could be promising candidates for transistor applications, and shed light on the molecular design of high performance materials.