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Recently, there has been a growing interest in developing porphyrin derivatives as electron donor materials in solution-processed organic solar cells. In contrast to the traditional synthesis route, we adopt a ligand-mediated supramolecular assembly approach to produce a new soluble porphyrin derivative. The complexation of nitrogen lone pairs in the bidentate ligands to the axial orbitals of both zinc atoms in zinc-metalated porphyrin dimers (KC2s) form KC2-duplex. The UV–vis absorbance of KC2-duplex displays a red-shift of the Q-band compared with that of KC2, indicating an improvement of intermolecular interaction. By blending KC2-duplex with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the photoactive material for fabricating organic bulk heterojunction solar cells, the devices demonstrate a 38.7% enhancement of short-circuit current density (Jsc) as compared to those made from dimers. The largely enhanced Jscis attributed to the improved charge transport dynamics of KC2-duplex:PC71BM blend, including the hole and effective mobilities and exciton dissociation probability. When the photoactive film is processed from solvent containing 3% v/v 1-chloronaphthalene, Jscis further enhanced (∼64.5%) as well as the fill factor (16.7%) for a power conversion efficiency of 3.06% from 1.63%. Our approach shown here can be generalized to other porphyrin-related systems to advance the development of porphyrin-based optoelectronic devices.

Imaging of thick biological samples has been very challenging because of severe light scattering. The transparent cornea with the unique organization of stromal collagen makes it a good candidate for deep imaging and is responsible for mechanical strength and optical clarity of the eye. However, limitation on traditional histology method provides incomplete spatial information and details on the structural organization of corneal tissue is still not sound. Second harmonic generation (SHG) microscopy is a noninvansive and nonstained technique to characterize the macromolecular organization of collagen in biological tissues. Through the combination of SHG microcopy and optimized Fourier-transform analysis, adult and embryonic chick corneas are investigated. Our results show that the anterior stroma demonstrates a fanlike distribution of rotated fibrous lamellae. In comparison with the anterior structure, the posterior stroma maintains a nonrotating pattern while increasing the depth of corneal tissue. In particular, the rotational pattern in anterior stroma exhibits a potential role of corneal maturation. Moreover, SHG microscopy in combination with the Fourier-transform-based analysis exhibits a useful tool in determination of collagen alignment in biological tissues and discrimination of diseases.

The presence of toxic lead (Pb) remains a major obstruction to the commercial application of perovskite solar cells. Although antimony (Sb)-based perovskite-like structures A3M2X9can display potentially useful photovoltaic behavior, solution-processed Sb-based perovskite-like structures usually favor the dimer phase, which has poor photovoltaic properties. In this study, we prepared a layered polymorph of Cs3Sb2I9through solution-processing and studied its photovoltaic properties. The exciton binding energy and exciton lifetime of the layer-form Cs3Sb2I9were approximately 100 meV and 6 ns, respectively. The photovoltaic properties of the layered polymorph were superior to those of the dimer polymorph. A solar cell incorporating the layer-form Cs3Sb2I9exhibited an open-circuit voltage of 0.72 V and a power conversion efficiency of 1.5%the highest reported for an all-inorganic Sb-based perovskite.