Feng Yan

Publications (51) View all

• Article: Oligothiophene-Bridged Bis(arylene ethynylene) Small Molecules for Solution-Processible Organic Solar Cells with High Open-Circuit Voltage.

  Qian Liu, Hongmei Zhan, Cheuk-Lam Ho, Feng-Rong Dai, Yingying Fu, Zhiyuan Xie, Lixiang Wang, Jin-Hua Li, Feng Yan, Shu-Ping Huang, Wai-Yeung Wong
  [show abstract] [hide abstract]
  ABSTRACT: A new series of conjugated oligothiophene-bridged bis(arylene ethynylene) small molecules have been designed, synthesized, and characterized by photophysical, electrochemical and computational methods. These compounds were found to have optimal LUMO levels that ensure effective charge transfer from these compounds to [6,6]-phenyl-C71 -butyric acid methyl ester (PC70 BM). They were utilized as good electron-donor materials that can be blended with electron-acceptor PC70 BM in the fabrication of solution-processed molecular bulk heterojunction (BHJ) solar cells. All of these BHJ devices showed very high open-circuit voltage (Voc ) of 0.90-0.97 V, and the best power conversion efficiency achieved was 3.68 %. The high Voc is consistent with the deeper low-lying HOMO level and is relatively insensitive to the donor : acceptor blend ratio. The spin-coated thin films of these small molecules showed p-channel field-effect charge transport with the hole mobilities of up to 2.04×10(-4) cm(2) V(-1) s(-1) . These compounds illuminate the potential of solution-processible small-molecular aryl acetylide compounds for efficient power generation in photovoltaic implementation.
  Chemistry - An Asian Journal 05/2013; · 4.50 Impact Factor
• Source

  Available from: Feng Yan

  Article: Package-Free Flexible Organic Solar Cells with Graphene top Electrodes.

  Zhike Liu, Jinhua Li, Feng Yan
  [show abstract] [hide abstract]
  ABSTRACT: Package-free flexible organic solar cells were fabricated with multilayer graphene as top transparent electrodes, which show the highest power conversion efficiency of about 3.2% and excellent flexibility and bending stability. The devices also show good air stability, indicating that multilayer graphene is a promising environmental barrier that can protect the organic solar cells from air contamination.
  Advanced Materials 04/2013; · 13.88 Impact Factor
• Article: Formation and Healing of Vacancies in Graphene Chemical Vapor Deposition (CVD) Growth.

  Lu Wang, Xiuyun Zhang, Helen L W Chan, Feng Yan, Feng Ding
  [show abstract] [hide abstract]
  ABSTRACT: The formation and kinetics of single and double vacancies in graphene chemical vapor deposition (CVD) growth on Cu(111), Ni(111) and Co(0001) surfaces are investigated by the van der Waals density functional theory calculation. It is found that the vacancies in graphene on the metal surfaces are dramatically different from those in free-standing graphene. The interaction between the vacancies and the metal surface and the involvement of a metal atom in the vacancy structure greatly reduce their formation energies and significantly change their diffusion barriers. Furthermore, the kinetic process of forming vacancies and the potential route of their healing during graphene CVD growth on Cu(111) and Ni(111) surfaces are explored. The results indicate that Cu is a better catalyst than Ni for the synthesis of high-quality graphene because the defects in graphene on Cu are formed in a lower concentration and can be more efficiently healed at the typical experimental temperature. This study leads to a deep insight into the atomic process of graphene growth and the mechanism revealed in this study can be used for the experimental design of high-quality graphene synthesis.
  Journal of the American Chemical Society 02/2013; · 9.91 Impact Factor
• Article: Hole-Transporting Transistors and Circuits Based on the Transparent Inorganic Semiconductor Copper(I) Thiocyanate (CuSCN) Processed from Solution at Room Temperature.

  Pichaya Pattanasattayavong, Nir Yaacobi-Gross, Kui Zhao, Guy Olivier Ngongang Ndjawa, Jinhua Li, Feng Yan, Brian C O'Regan, Aram Amassian, Thomas D Anthopoulos
  [show abstract] [hide abstract]
  ABSTRACT: The wide bandgap and highly transparent inorganic compound copper(I) thiocyanate (CuSCN) is used for the first time to fabricate p-type thin-film transistors processed from solution at room temperature. By combining CuSCN with the high-k relaxor ferroelectric polymeric dielectric P(VDF-TrFE-CFE), we demonstrate low-voltage transistors with hole mobilities on the order of 0.1 cm(2) V(-1) s(-1) . By integrating two CuSCN transistors, unipolar logic NOT gates are also demonstrated.
  Advanced Materials 12/2012; · 13.88 Impact Factor
• Article: A structural stability diagram of multiple vacancies and defect self-healing in graphene.

  Lu Wang, Feng Yan, Helen L W Chan, Feng Ding
  [show abstract] [hide abstract]
  ABSTRACT: Various types of multiple vacancies (MVs) in graphene nanoribbons (GNRs) and graphene are explored by quantum calculations. It is surprising that their relative stabilities highly depend on the width of the GNRs and thus is significantly different from those in graphene. A diagram of various MVs in GNRs is drawn and it is predicated that the hole in both GNRs and graphene can be annihilated. A new type of the MVs, which contains pentagon pairs and octagons (5/5|8), shows exceptional stability in GNRs. This study reveals the uniqueness of GNRs and a mechanism of defect self-healing in GNRs and graphene.
  Nanoscale 10/2012; · 5.91 Impact Factor