Xiaoyang Guo

Monodisperse Co-oligomer Approach toward Nanostructured Films with Alternating Donor-Acceptor Lamellae

A series of donor-acceptor (D-A) co-oligomers with oligo(fluorene-alt-bithiophene) and perylene diimide as donor and acceptor segments, respectively, have been designed and synthesized. They can self-assembly into alternating D-A lamellar nanostructured films with the periods depending on the molecular length. These films have been successfully used in fabrication of high-performance single-molecular solar cells with power conversion efficiency up to 1.50%.

Alkyl substituted [6,6]-thienyl-C61-butyric acid methyl esters: easily accessible acceptor materials for bulk-heterojunction polymer solar cells

[6,6]-Thienyl-C61-butyric acid ester derivatives with methyl, hexyl and 2-ethylhexyl at the 5-position of thiophene ring (TCBM-Cn, n represents the number of carbon atom in the alkyl chain) were synthesized. Unlike [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), these methanofullerene derivatives ([6,6] adduct) can be directly obtained from the typical diazo addition under mild conditions, and high temperature isomerization is unnecessary. With a hexyl or 2-ethylhexyl group at the 5-position of thiophene, the solubility of TCBM-Cn in chlorobenzene is as high as 180 ± 10 mg ml−1. Bulk heterojunction photovoltaic solar cells were fabricated with a device structure of ITO/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/poly(3-hexylthiophene) (P3HT)u2006:u2006TCBM-Cn (1u2006:u20060.8 w/w)/LiF/Al. The device based-on TCBM-C6 exhibited the best performance with a power conversion efficiency (PCE) of up to 4.26%.

Microstructure of poly-Si thin films prepared at low temperatures

Abstract Microstructures of hydrogenated polycrystalline silicon (poly-Si) and microcrystalline silicon (μc-Si:H) thin films prepared by hot wire chemical vapor deposition (HWCVD) with hydrogen dilution of silane have been studied. The columnar crystal growth of the film was clearly visible starting from substrate. The transmission electron diffraction (TED) showed the typical polycrystalline material with small crystals. The (1xa01xa01) preferential grain was observed in poly-Si films. The 2100xa0cm−1 stretching vibration mode splits into two modes centered at around 2082 and 2098xa0cm−1 which are suggested to be the Si–H modes at the nanocrystalline Si (1xa011) and (1xa01xa00) surfaces, respectively.