Stop Blaming Hopping Conduction in Nanocrystal Arrays, Use It for Active Photonics!

AbstractNanocrystals (NCs) are now established building blocks for photonic applications. However, their integration for optoelectronics has not yet reached the same level of maturity, in part due to the perceived bottleneck that is the inherent limited mobility resulting from hopping conduction. Significant efforts are made to improve this mobility, notably by tuning the particle surface chemistry to enable larger interparticle electronic coupling, and values of mobility of ≈10 cm2 V−1 s−1 have been achieved. It is acknowledged that this value remains significantly lower than those obtained in 2D electron gases but is on par with the mobility reported for vertical transport in epitaxially grown heterostructures with similar confinement energies. Since there appears to be limited perspectives for further increasing mobility values, a suggestion is made that efforts should instead be directed toward exploring the potential benefits offered by hopping conduction. One of these benefits is the bias dependence of the diffusion length, which plays a key role in designing bias‐reconfigurable optical responses for NC‐based devices. Some recent achievements in building bias‐activated devices will be reviewed and the essential criteria for designing future structures will be discussed. Ultimately, hopping conduction is an opportunity to generate new functionalities that low‐disorder materials would be unable to provide.