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Organic solar cells (OSCs) have shown great promise as low‐cost photovoltaic devices for solar energy conversion over the past decade. Interfacial engineering provides a powerful strategy to enhance efficiency and stability of OSCs. With the rapid advances of interface layer materials and active layer materials, power conversion efficiencies (PCEs) of both single‐junction and tandem OSCs have exceeded a landmark value of 10%. This review summarizes the latest advances in interfacial layers for single‐junction and tandem OSCs. Electron or hole transporting materials, including metal oxides, polymers/small‐molecules, metals and metal salts/complexes, carbon‐based materials, organic‐inorganic hybrids/composites, and other emerging materials, are systemically presented as cathode and anode interface layers for high performance OSCs. Meanwhile, incorporating these electron‐transporting and hole‐transporting layer materials as building blocks, a variety of interconnecting layers for conventional or inverted tandem OSCs are comprehensively discussed, along with their functions to bridge the difference between adjacent subcells. By analyzing the structure–property relationships of various interfacial materials, the important design rules for such materials towards high efficiency and stable OSCs are highlighted. Finally, we present a brief summary as well as some perspectives to help researchers understand the current challenges and opportunities in this emerging area of research.

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The past decade has witnessed increasing attention in the synthesis, properties, and applications of one-dimensional (1D) conducting polymer nanostructures. This overview first summarizes the synthetic strategies for various 1D nanostructures of conjugated polypyrrole (PPy), polyaniline (PANI), polythiophene (PTh), poly(p-phenylenevinylene) (PPV) and derivatives thereof. By using template-directed or template-free methods, nanoscale rods, wires/ fibers, belts/ribbons, tubes, arrays, or composites have been successfully synthesized. With their unique structures and advantageous characteristics (e.g., high conductivity, high carrier mobility, good electrochemical activity, large specific surface area, short and direct path for charge/ion transportation, good mechanical properties), 1D conducting polymer nanostructures are demonstrated to be very useful for energy applications. Next, their applications in solar cells, fuel cells, rechargeable lithium batteries, and electrochemical supercapacitors are highlighted, with a strong emphasis on recent literature examples. Finally, this review ends with a summary and some perspectives on the challenges and opportunities in this emerging area of research.

Four ladder-type oligo-p-phenylene containing donor-acceptor copolymers were designed, synthesized, and characterized. The ladder-type oligo-p-phenylene was used as an electron donor unit in these copolymers to provide a deeper highest occupied molecular orbital (HOMO) level for obtaining polymer solar cells with a higher open-circuit voltage, while 4,7-dithien-2-yl-2,1,3-benzothiadiazole or 5,8-dithien-2-yl-2,3-diphenylquinoxaline was chosen as an electron acceptor unit to tune the electronic band gaps of the polymers for a better light harvesting ability. These copolymers exhibit field-effect mobilities as high as 0.011 cm(2)/(V s). Compared to fluorene containing copolymers with the same acceptor unit, these ladder-type oligo-p-phenylene containing copolymers have enhanced and bathochromically shifted absorption bands and much better solubility in organic solvents. Photovoltaic applications of these polymers as light-harvesting and hole-conducting materials are investigated in conjunction with [6,6]-phenyl-C61-butyric acid methyl ester (PC(61)BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC(71)BM). Without extensive optimization work, a power conversion efficiency (PCE) of 3.7% and a high open-circuit voltage of 1.06 V are obtained under simulated solar light AM 1.5 G (100 mW/cm(2)) from a solar cell with an active layer containing 20 wt % ladder-type tetra-p-phenylene containing copolymer (P3FTBT6) and 80 wt % PC(61)BM. Moreover, a high PCE of 4.5% was also achieved from a solar cell with an active layer containing 20 wt % P3FTBT6 and 80 wt % PC(71)BM.

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This paper reports the design, synthesis, and theoretical modeling of two‐photon properties of a new class of chromophore that exhibits enhanced two‐photon absorption (TPA) and subsequently generated strong up‐converted emission in nanoaggregate forms. This chromophore utilizes the basic structural unit of 9,10‐bis[4′‐(4″‐aminostyryl)styryl]anthracene that exhibits large internal rotation in the monomer form in organic solvents, whereby the fluorescence is greatly reduced. In nanoaggregates formed in water, the internal rotation is considerably hindered, leading to significant increases of TPA and fluorescence quantum yield. Theoretical modeling of the conformational structure and dynamics has utilized a semiempirical pm3 formalism. The TPA cross sections of the monomer and the aggregate states have been calculated on the basis of the quadratic response theory applied to a single‐determinant self‐consistent field reference state making use of a split‐valence 6‐31G* basis set.

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