Towards scalable fabrication of high efficiency organic solar cells
L. Jay Guo
Department of Electrical Engineering and Computer Science
The University of Michigan, Ann Arbor, MI, 48109
Time: March 6 (Wed), 9:15am
Location: Joint Institute Conference room (2nd floor)
Bulk heterojunction (BHJ) OPV is one of the most successful structures giving the highest efficiencies for polymer PV cells. The nano domain morphology is important for the charge separation and transport, and directly impact the device performance. Traditional spin-coating method and the long annealing processes are not compatible with large scale fabrication of polymer PV. To address these issues, we introduce a new fabrication process (termed ESSENCIAL). The process leads to optimized morphology with more uniform distribution and crystallinity of the components favorable for charge generation and transport that cannot be achieved by conventional thermal and solvent annealing methods. Furthermore the ESSENCIAL technique can be extended to the fabrication of bilayer polymer PVs, which significantly facilitates interdiffusion between the donor and acceptor layers inducing optimized morphology and a record high photocurrent in the P3HT/PCBM system. We will also show that the transparent electrodes based on metallic nano-mesh is a strong candidate as a replacement of conventional ITO electrode due to their superior properties, such as high optical transparency, good electrical conductivity and mechanical flexibility. Furthermore, the unique optical properties due to the excitation of surface plasmon resonance can be exploited to enhance the light absorption by the organic semiconductors. In an effort to harvest the light energy absorbed and wasted in displays, we designed a special MIM-type nanoresonator structure that incorporates the organic semiconductors. The device produces photocurrent from the absorbed light and can simultaneously function as reflection color filter. If time allows, a second topic will be discussed of using laser generated focused high-frequency ultrasound for targeted cell therapy induced by the cavitation bubbles.
L. Jay Guo received his B.S. in Physics (Biophysics major) from Nankai University, China in 1990, and his MS and Ph.D. in Electrical Engineering from the University of Minnesota in 1995 and 1997 respectively. He was a research associate at Princeton University from 1998-1999. He joined the Department of Electrical Engineering and Computer Science at the University of Michigan, Ann Arbor in 1999, and is currently a professor of Electrical Engineering and Computer Science, and with appointment in Applied Physics, Mechanical Engineering, and Macomolecular Science and Engineering. He has over 120 refereed journal publications and served on many international conference program committees related to nanotechnologies and photonics. His research areas include polymer-based photonic devices and sensor applications, organic electronics and photonics, plasmonic nanophotonics, high-throughput nanomanufacturing technology and applications.