Hot Carrier cells aim to collect hot carriers resulting from photon absorption before they thermalise. This requires slowed carrier cooling in an absorber material and collection through narrow energy selective contacts. Previous work has proved the concept of these energy selective contacts using resonant tunnelling in Si quantum dot (QD) double-barrier structures. Further experimental work on electrical and optical excitations of these structures is shown. Modelling work has demonstrated the possibility of slowing the rate of carrier cooling by modifying the phonon dispersion in QD superlattices. Developments in this modelling which indicate the critical importance of the interface are also presented. (C) 2008 Elsevier B.V. All rights reserved.