To Be or not to Be: Band-Like Transport in Quantum Dot Solids

Recent experimental data on charge carrier transport in quantum dot solids is analyzed in light of the question whether band-like transport is the most plausible mechanism to account for the observed behavior. Upon reviewing some physical fundamentals of temperature-activated hopping, small polaron hopping and band-like transport, it is established that a combined approach of different experimental methods is required to achieve a satisfactory degree of unambiguousness to address this question. In doing so, at least one example is identified for which a high degree of supporting evidence exists that transport is in fact diffusive. It is highlighted that temperature-dependent Hall Effect measurements play an important role in this respect.