Organic electronics, photovoltaics

Organic semiconducting micro crystals show high potential for the applications in microelectronic devices and flexible electronics due to the long-range-ordered molecular packing and absence of grain boundaries. The most organic single crystals indicates a highly anisotropic optical behaviour. Imaging Ellipsometry is the most appropriate tool to characterize the optical properties of thin micro crystals.

Conductive polymers and polymer-fullerene blends are promising materials for OLED and plastic solar cell applications. Blends prepared by two different methods, silk-printing and spin-coating were imaged, characterized and mapped using the spectroscopic imaging ellipsometer at two magnifications, 10X and 2X. The mean value of the layer thickness and the optical properties of selected regions of interest were obtained from UV/VIS spectra of Delta and Psi. The local distribution and location of optical properties was obtained from delta maps.

Since several years the development of organic semi-conductor materials as active layer for organic solar cells has become one of the main challenges in chemis-try and applied physics. π-conjugated polymers are one of most efficient exponent regarding optical and elec-tronic properties for organic solar cells. The π-conjugated polymers stand out due to their structural di-versity and optoelectronic properties. The modification of the donor-acceptor-donor (DAD) architecture is a simple and efficient way to construct a well-defined π-conjugated system with low oxidation potential, broad absorption spectrum and low band-gap. Controlling the morphology, homogeneity and the optical properties of the organic photovoltaic material is essential for optimiz-ing the efficiency of organic solar cells when employing π-conjugated polymers as photoactive layer.

Here we present the optical properties of two DAD type π-conjugated polymer films (poly-10,13-bis(4-hexylthiophen-2-yl)dibenzo[a,c]phenazine (poly-PHEHT) and poly-5,8-bis(4-hexylthiophen-2-yl)-2-(2,3-dihydrobenzo[b][1,4]dioxin-7-yl)quinoxaline (poly-DBQHT) Fig. 1) on indium tin oxide (ITO) doped glass slide .

Characterization of spin-coated thin-film plastic solar cell material on glass by spectroscopic imag-ing ellipsometry and ATR-FTIR (Poster, 2013)

Application of Imaging Ellipsometry: Characterization of bulk-heterojunction layers by imaging ellipsometry (Poster, 2011)