Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 72: Poster Session: Si-based Photovoltaics / Inorganic Photovoltaics / Structure and Transport in Organic Photovoltaics / Organic Semiconductors
HL 72.32: Poster
Wednesday, March 28, 2012, 16:00–19:00, Poster D
Influence of charge carrier density and dimensionality on transport properties of (DCNQI-d6)2Cu radical anion salts — •Florian Hüwe1, Matthias Schmiddunser1, and Jens Pflaum1,2 — 1Experimental Physics VI, Julius-Maximilians-University Würzburg, D-97074 Würzburg — 2ZAE Bayern e.V., D-97074 Würzburg
Due to their quasi-1D band structure the highly conducting organic (DCNQI-d6)2Cu radical anion salts provide an insight into the physics of low-dimensional metals. Compared to ordinary 3D metals they undergo a first-order Peierls metal-insulator transition upon cooling and show much more pronounced interactions with electrons and phonons.
Our contribution reports on the electrocrystallization of needle-like (DCNQI)2Cu single crystals with extensions of up to 3cm along the (001) direction of high conductivity and thicknesses up to 125µ m along the (010) normal. Characterization by XRD, Raman spectroscopy and transport measurements confirms the high quality of the samples. Their room-temperature conductivities reach values up to σ=1200 S cm−1 and show Ohmic behaviour. Raman spectra indicate an increase in charge carrier density on the crystallized DCNQI molecules compared to the neutral molecules causing partial filling of the conduction band. Upon cooling the (DCNQI)2Cu crystal undergo a characteristic Peierls transition at Tp=75K. To further elucidate effects by size and carrier concentration, these results will be compared to sub-µ m sized crystallites smaller than 5µ m and to crystals with modified charge carrier densities.