Exciton effects in perovskite nanocrystals

Nanocrystals (NCs) of perovskite materials have recently attracted great research interest because of their outstanding properties for optoelectronic applications, as evidenced by the increasing number of publications on laboratory scale devices. However, in order to achieve the commercial realisation of these devices, an in-depth understanding of the charge dynamics and photo-physics in these novel materials is required. These dynamics are affected by material composition but also by their size and morphology due to quantum confinement effects. Advances in synthesis methods have allowed nanostructures to be produced with enhanced confinement and structural stability, enhancing the efficiency of energy funnelling and radiative recombination and so resulting in more efficient light emitting devices. In addition, photovoltaics could greatly benefit from the exploitation of these materials not only through their deployment in tandem cell architectures but from the use of multiple exciton generation in these NCs. These systems also offer the opportunity to study quantum effects relating to interactions of excited states within and between NCs. Properties and behaviour that includes an enhanced Rashba effect, superfluorescence, polariton lasing, Rydberg exciton polariton condensates, and antibunched single photon emission have been observed in a single metal halide perovskite NC. The further study of these in NC systems will shed new light on the fundamental nature of their excited states, their control and exploitation. In this perspective, we give an overview of these effects and provide an outlook for the future of perovskite NCs and their devices.