In recent years, progress in the synthesis, and, especially, surface chemistry of colloidal nanomaterials led to steadily improved electronic coupling, conductivity and charge mobility in nanocrystal films. This has important implications for performance of nanomaterials in various devices, where high mobility helps to collect charges in photodetectors and solar cells, and maximizes brightness of LEDs and lasers. We discuss a set of experimental studies for quantum dot (QD) and metal nanocrystal arrays which show unprecedentedly good electronic properties and provide a new platform for in-depth studies of charge transport through a network of discrete quantum-confined electronic states. To the best of our knowledge, we demonstrate the first instance of resolved charge filling of quantum states in solid state QD devices. This has been achieved by applying a novel hybrid surface passivation process that efficiently eliminated surface states, thus allowing for reversible charging of QDs, switching between n-type and p-type transport, and air-stable tunable doping. For QD films casted at room temperature without any post treatments, we observe “band-like” transport at temperatures above 70K. Furthermore, the measured FET mobilities up to ~8 cm2V-1s-1 are similar to the measured Hall mobility. This opens up a host of exciting opportunities for QD technologies and also raises important questions about the degree of electron delocalization and transport in QD solids. These questions are vital to the prospects of colloidal QDs for competitive electronic and optoelectronic technologies.

Electronic coupling and dissipative transport in non-covalent inorganic nanoscale assemblies

2019 Fall National Meeting

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