Assemblies of Colloidal CdSe Tetrapod Nanocrystals with Lengthy Arms for Flexible Thin-Film Transistors

Herein, we report unique features of the assemblies of tetrapod-shaped colloidal nanocrystals (TpNCs) with lengthy arms applicable to flexible thin-film transistors. Due to the extended nature of tetrapod geometry, films made of the TpNC assemblies require reduced numbers of inter-NC hopping for the transport of charge carriers along a given channel length; thus, enhanced conductivity can be achieved compared to those made of typical spherical NCs without arms. Moreover, electrical conduction through the assemblies is tolerant against mechanical bending because interconnections between TpNCs can be well-preserved under bending. Interestingly, both the conductivity of the assemblies and their mechanical tolerance against bending are improved with an increase in the length of tetrapod arms. The arm length-dependency was demonstrated in a series of CdSe TpNC assemblies with different arm lengths (l = 0–90 nm), whose electrical conduction was modulated through electrolyte gating. From the TpNCs with the longe...