Quantum Dot Solids Challenge Traditional Charge Transport Models
Researchers from the Helmholtz-Zentrum Berlin have shed new light on charge transport in quantum dot solids, potentially opening doors to new electrical applications. Their study, published in 2020, challenges traditional models and offers a novel approach to controlling electrical properties.
The team, led by Xiangxi Yin and Bence Papp, found that charge transport in lead sulfide (PbS) quantum dot arrays does not adhere to Ohm's Law or the Drude model. Instead, it exhibits characteristics of Lévy statistics and non-ergodic behavior. This unexpected finding was made possible by a novel nano-patterning technique developed by the team, which created a highly ordered quantum dot solid.
The researchers also discovered unexpectedly high levels of conductance noise in these materials, exceeding the average current. This breakthrough challenges the conventional understanding of charge transport in colloidal nanocrystal solids. The team models this behavior using a quasi-one-dimensional percolation approach, providing a detailed insight into the underlying mechanisms.
Surface chemistry and passivation were found to play a crucial role in controlling the density of trap states and improving charge transport in quantum dot arrays. This understanding paves the way for designing quantum dot solids with precisely tailored electrical properties, expanding their potential applications beyond their current success in tunable optical properties.
The Helmholtz-Zentrum Berlin's research represents a significant step forward in understanding and controlling charge transport in quantum dot solids. By challenging traditional models and offering a novel approach, this work brings us closer to realizing reliable electrical conductivity in these materials, a long-standing challenge in the field.
