Artificial solids constructed from colloidal quantum dot (QD) building blocks promise materials with tunable electronic properties. Yet high carrier mobilities and conductivities have been limited by weak coupling and low carrier concentrations. We report band-like transport in solution-deposited, CdSe QD thin-films with room temperature field-effect mobilities for electrons of 27 cm2/Vs. A concomitant shift and broadening in the QD solid optical absorption compared to that of dispersed samples is consistent with electron delocalization and measured electron mobilities. Annealing Indium contacts allows for thermal diffusion and doping of the QD thin-films, shifting the Fermi energy, filling traps, and providing access to the bands. Temperature dependent measurements show band-like transport to 220K on an SiO2 gate insulator, that is extended to 140 K by reducing the interface trap density using an Al2O3/SiO2 gate insulator. The use of compact ligands and doping provides a pathway to high performance, solution-deposited QD electronics and optoelectronics.
Citation: Nature Nanotechnology
Pub Type: Journals
Field effect transistors, quantum dots, indium distribution