Mesoporous Matrices as Hosts for Metal Halide Perovskite Nanocrystals

Abstract

Several works have recently demonstrated that perovskite nanocrystals can be controllably formed within a variety of porous matrices employing diverse synthetic strategies. By means of the fine tuning of the pore size distribution, the thickness and composition of the walls, the geometry of the void network and its topology, strict control over the structural and morphological parameters of the hosted semiconductor can be achieved, determining its optical absorption and emission properties. Furthermore, porous hosts provide the guest semiconductor with enhanced stability and versatility in terms of processing, which favors its integration in devices. This article provides a comprehensive review of the different approaches proposed, as well as a discussion on the relevance they may have for the development of nanostructured perovskite‐based optoelectronics. A critical assessment of the optical quality of the hybrid perovskite nanomaterials so obtained is presented, as well as an analysis of the fundamental and applied aspects of the nanocrystal–matrix interaction and a projected prospect of their impact in the fields of artificial lighting and renewable energy.

The impact of ligands on the synthesis and application of metal halide perovskite nanocrystals

“…Besides compositional modications, quantum-size effects have a major role in tuning the band gap of MHP NCs. 30 To achieve quantum connement, the size of the NC should be similar to or smaller than the Bohr exciton radius, which is the most probable delocalization distance of an exciton in the bulk semiconductor. This connement results in a blue shi of the absorption and emission of the NC with respect to its bulk form.…”

“…81 Studying the PLQY values of perovskite NCs along with their PL decay dynamics gives insights regarding the radiative and non-radiative recombination processes and therefore understanding the defects and trap states in these NCs. 30 As in any semiconductor material, the lifetime of excited states in MHP NCs is usually shorter than that of its bulk counterpart. In the case of inorganic CsPbX 3 NCs, time-resolved PL measurements show a bi-exponential decay with a radiative lifetime in the nanosecond range between 1 and 29 ns.…”

“…[85][86][87] Shallow defects do not affect the charge carrier transport and the radiative recombination in these NCs. 30 This defect tolerance in MHP NCs is the reason of their very bright photoluminescence and their efficient utilization in solar cells and LED devices without the need of electronic surface passivation as in the case of metal chalcogenide QDs. 13,57 The differences between MHPs and the conventional semiconductors in terms of the effect of defects on their electronic properties is illustrated in Fig.…”

“…9,13,14,16,28 The main focus of these reviews was the synthesis of the perovskite NCs and their applications. Recently, more specic reviews have been published encountering precise issues related to metal halide perovskite nanocrystals, such as doping with lanthanide, 29 using mesoporous matrices as hosts for the nanocrystals 30 and lead-free halide nanocrystals. 31 Even though ligands have a profound effect on the growth and morphological, structural and optoelectronic properties perovskite NCs, the type of interaction between the perovskite nanocrystals and capping ligands has been signicantly less discussed.…”

Efficient third harmonic generation from FAPbBr3 perovskite nanocrystals

“…Simultaneously, self-aggregation is prevented, as the matrix also favours the dispersion of the nanocrystals. 18,20,21 Quantitative analysis of the elemental lead present in the film by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) reveals a 6.5 AE 0.1 vol% of FAPbBr 3 nanocrystals in the film, which implies that silica and air occupy 50% and 43.5% of the composite volume respectively. Linear optics characterisation ncFAPbBr 3 @SiO 2 films show exciton quantum confinement effects, as evidenced in Fig.…”