PhD Colloquium by Mr. Arun Dhumal Rao (4pm, 10th July 2015)

Name of student : Mr. Arun Dhumal Rao.

Thesis title : “Interface engineering and evaluation of device performance in organic photovoltaics”

Faculty advisor : Prof. Praveen C. Ramamurthy

Date : Friday 10th July 2015

Time : 4.00 P.M

Venue : Material Engineering Lecture Theatre

The performance and lifetime of Organic Photovoltaic (OPV) devices are
significantly reliant on the properties of both the active materials and
their interfaces. Properties such as wetting and adhesion between adjacent
materials are also essential for device performance. Therefore,
understanding of interface between organic semiconductor and inorganic
/metal electrode is vital. In this work we look at modifying active layer,
buffer layer, electrode layer and device substrate. Active layer is
modified by addition of low band gap polymer as a ternary component in a
binary mixture, for enhanced light absorption from the solar spectrum. To
evaluate its enhanced Photovoltaic device performance, we characterized
evolution of morphology, charge transfer and transport properties of
active layer. In another case, the buffer layer was engineered into highly
aligned nanostructure to evaluate interaction with active layer and its
enhanced photovoltaic properties.

Device was also fabricated on opaque fiber reinforced plastic (FRP)
substrates. Since it is an opaque substrate, we developed top illuminated
conducting layer. Further since the FRP substrate is rough to fabricate
device, FRP surface was planarized by using unique layer which binds
synergistically with the FRP and device surface. Modified metal electrode
was deposited on the planarized substrate and its adhesion properties were
evaluated. Using this metal electrode OPV device was fabricated using top
illuminated conducting layer and performance of device was optimized using
bandgap engineering. Further device was fabricated on flexible glass
substrate, using two different transparent conducting layers. Since, its
flexible substrate, we carried out insitu flexural-PV measurements to
evaluate its device performance during flexing. Hence, during fabrication,
we look at unique challenges associated with fabrication on substrates and
understand the effect of each interface and active layer on performance of