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Postdeposition Ligand Exchange Allows Tuning the Transport Properties of Large‐Scale CuInSe2 Quantum Dot Solids

: Gorris, Friederieke E.S.; Deffner, Michael; Priyadarshi, Shekhar; Klinke, Christian; Weller, Horst; Lange, Holger

Fulltext ()

Advanced optical materials 8 (2020), No.1, Art. 1901058, 8 pp.
ISSN: 2195-1071
Deutsche Forschungsgemeinschaft DFG
Advanced Imaging of Matter; EXC 2056
Journal Article, Electronic Publication
Fraunhofer IAP ()

Colloidal quantum dots assembled into quantum dot solids usually suffer from poor conductivity. The most common charge transport mechanism through the solid is hopping transport where the hopping probability depends on the barrier type (stabilizing/connecting ligand molecule) and the interparticle distance. It is demonstrated that the electronic structure of the ligand molecule strongly alters the transport behavior through CuInSe2 quantum dot solids. Transport measurements and optical‐pump terahertz‐probe experiments after a ligand exchange to fully conjugated molecules show an increase of the conductivity by orders of magnitude, as well as a change of the hopping transport mechanism. This change is not due to a reduced interparticle distance, but the electronic structure: the obtained frequency‐dependent complex conductivities point toward an efficient hole transport enabled by an alignment of the quantum dot valence bands and ligand states.