Selective energy contacts for potential application to hot carrier PV cells

Hot carrier solar cells offer the possibility of enhanced efficiency by slowing the carrier cooling caused by phonon interaction. To be effective such carriers must be collected over a very small energy range with selective energy contacts. The current work concludes that the key requirement for such contacts is a very narrow selective energy range and that the energy of carriers is confined in all three dimensions not just longitudinally. The paper then discusses some structures that may be able to achieve this together with the direction of preliminary experimental work. The structures considered exploit resonant tunnelling and include defect levels as confined levels in a barrier matrix and interband degenerate tunnel junctions.